485BPOS

As filed with the U.S. Securities and Exchange Commission on November 13, 2019

File No. 033-47287

File No. 811-06637

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C.  20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933	x
Pre-Effective Amendment No.	o
Post-Effective Amendment No. 142	x

and/or

REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940	x
Amendment No. 143

(Check appropriate box or boxes.)

THE UBS FUNDS

(Exact Name of Registrant as Specified in Charter)

One North Wacker, Chicago, Illinois  60606

(Address of Principal Executive Office)  (Zip Code)

Registrant’s Telephone Number, including Area Code  312-525-7240

Keith A. Weller

UBS Asset Management (Americas) Inc.

One North Wacker

Chicago, Illinois  60606

(Name and Address of Agent for Service)

Please send copies of all communications to:

Jana L. Cresswell, Esq.

Stradley Ronon Stevens & Young, LLP

2005 Market Street, Suite 2600

Philadelphia, PA 19103

(215) 564-8048

Approximate Date of Proposed Public Offering: As soon as practicable after the effective date of this registration statement.

It is proposed that this filing will become effective (check appropriate box):

x  immediately upon filing pursuant to paragraph (b)

o  on [Date] pursuant to paragraph (b)

o  60 days after filing pursuant to paragraph (a)(1)

o  on [Date] pursuant to paragraph (a)(1)

o  75 days after filing pursuant to paragraph (a)(2)

o  on [Date] pursuant to paragraph (a)(2) of Rule 485.

If appropriate, check the following box:

o  This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended (the “Securities Act”), and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness of this Registration Statement under Rule 485(b) under the Securities Act and has duly caused Post-Effective Amendment Nos. 142/143 to this Registration Statement on Form N-1A to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Chicago, and the State of Illinois on the 13th  day of November, 2019.

THE UBS FUNDS
By:	/s/ Igor Lasun
	Igor Lasun*
	President and Principal Executive Officer

Pursuant to the requirements of the Securities Act, this Registration Statement has been signed below by the following persons in the capacities and on the dates indicated:

Signature	Title	Date
/s/ Igor Lasun	President and	November 13, 2019
Igor Lasun*	Principal Executive Officer
/s/ Frank K. Reilly	Chairman and Trustee	November 13, 2019
Frank K. Reilly*
/s/ Joanne M. Kilkeary	Principal Accounting Officer	November 13, 2019
Joanne M. Kilkeary*	and Treasurer
/s/ Adela Cepeda	Trustee	November 13, 2019
Adela Cepeda*
/s/ J. Mikesell Thomas	Trustee	November 13, 2019
J. Mikesell Thomas*
/s/ Abbie J. Smith	Trustee	November 13, 2019
Abbie J. Smith*

* By	/s/ Keith A. Weller
	Keith A. Weller, Attorney-in-Fact
	(Pursuant to Powers of Attorney, incorporated herein by reference)

EXHIBITS INDEX

Index No.	Description of Exhibit
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.CAL	XBRL Taxonomy Extension Calculation Linkbase
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase

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UBS U.S. Sustainable Equity Fund

UBS U.S. Sustainable Equity Fund

Investment objective

The Fund seeks to maximize total return, consisting of capital appreciation and current income.

Fees and expenses

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder fees (fees paid directly from your investment)

Shareholder Fees - UBS U.S. Sustainable Equity Fund	Class A		CLASS P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	5.50%		none
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	none	[1]	none

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - UBS U.S. Sustainable Equity Fund		Class A	CLASS P
Management fees		0.70%	0.70%
Distribution and/or service (12b-1) fees		0.25%	none
Other expenses	[1]	1.19%	1.15%
Total annual fund operating expenses		2.14%	1.85%
Less management fee waiver/expense reimbursements	[2]	1.19%	1.15%
Total annual fund operating expenses after management fee waiver/expense reimbursements	[2]	0.95%	0.70%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example - UBS U.S. Sustainable Equity Fund - USD ($)	1 year	3 years	5 years	10 years
Class A	642	1,075	1,533	2,798
CLASS P	72	470	893	2,075

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 102% of the average value of its portfolio.

Principal strategies

Principal investments

To achieve its investment objective, the Fund invests in, or seeks exposure to companies based on various financial factors and fundamental sustainability factors such as environmental, social and governance performance of such companies.

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in equity securities of US companies. Investments in equity securities may include, but are not limited to, dividend-paying securities; common stock; preferred stock; equity securities of real estate investment trusts ("REITs"); shares of investment companies, including exchange-traded funds ("ETFs"); convertible securities; warrants and rights.

The Fund may, but is not required to, use exchange-traded derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include futures and forward currency agreements. These derivatives may be used for risk management purposes to manage or adjust the risk profile of the Fund. Futures on currencies and forward currency agreements may also be used to hedge against a specific currency. In addition, futures on indices may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments; or to obtain exposure to certain markets.

The Fund may engage in active and frequent trading of portfolio securities to achieve its principal investment strategies.

Under certain market conditions, the Fund may invest in companies at the time of their initial public offering ("IPO").

Management process

The Advisor's investment decisions are based upon price/value discrepancies as identified by the Advisor's fundamental valuation process. In selecting securities, the Advisor focuses on, among other things, identifying discrepancies between a security's fundamental value and its market price. In this context, the fundamental value of a given security is the Advisor's assessment of what a security is worth. The Advisor will select a security whose fundamental value it estimates to be greater than its market value at any given time. For each stock under analysis, the Advisor bases its estimates of value upon economic, industry and company analysis, as well as upon a company's management team, competitive advantage and core competencies. The Advisor then compares its assessment of a security's value against the prevailing market prices, with the aim of constructing a portfolio of stocks with attractive relative price/value characteristics.

The Advisor will employ both a positive and negative screening process in selecting securities for the Fund. The positive screening process will identify securities of companies that are fundamentally attractive and that have superior valuation characteristics. In addition, the positive screening process will also include material, fundamental sustainability factors that the Advisor believes confirm the fundamental investment case and can enhance the ability to make good investment decisions. The sustainability factors are material extra-financial factors that evaluate the environmental, social and governance performance of companies that, along with more traditional financial analytics, identify companies that the Advisor believes will provide sustained, long-term value. The Advisor believes that the sustainability strategy provides the Fund with a high quality portfolio and mitigates risk.

The Advisor also applies a negative screening process that will exclude from the Fund's portfolio securities with more than 5% of sales in industries such as alcohol, tobacco, defense, nuclear, GMO (Genetically Modified Organisms), gambling and pornography. The Advisor may modify this list of negative screens at any time, without prior shareholder approval or notice.

Main risks

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Focused investment risk: The risk that investing in a select group of securities could subject the Fund to greater risk of loss and could be considerably more volatile than the Fund's primary benchmark or other mutual funds that are diversified across a greater number of securities.

Portfolio turnover risk: High portfolio turnover from frequent trading will increase the Fund's transaction costs and may increase the portion of the Fund's capital gains that are realized for tax purposes in any given year. The Fund does not restrict the frequency of trading in order to limit expenses or the tax effect that its distributions may have on shareholders.

Sustainability factor risk: The Fund's sustainability factors used in its investment process will likely make the Fund perform differently from a fund that relies solely or primarily on financial metrics. The sustainability factors may cause the Fund's industry allocation to deviate from that of funds without these considerations.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments, and they may have more limited resources.

IPOs risk: The purchase of shares issued in IPOs may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market securities. In addition, non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Performance

Risk/return bar chart and table

The performance information that follows shows the Fund's performance information in a bar chart and an average annual total returns table. The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance. An index reflects no deduction for fees, expenses or taxes. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. In October 2017, the Fund's investment strategies changed. The performance below for periods prior to that date is attributable to the Fund's performance before the strategy change. Updated performance for the Fund is available at www.ubs.com/us-mutualfundperformance.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Total return (Class P)

Total return January 1 - September 30, 2019: 22.68%
Best quarter during calendar years shown—2Q 2009: 19.55%
Worst quarter during calendar years shown—3Q 2011: (16.87)%

Average annual total returns (figures reflect sales charges) (for the periods ended December 31, 2018)

Average Annual Returns - UBS U.S. Sustainable Equity Fund	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years	Average Annual Returns, Inception Date
Class A	(14.26%)	5.11%	10.94%	Jun. 30, 1997
CLASS P	(9.04%)	6.57%	11.86%	Feb. 22, 1994
After Taxes on Distributions | CLASS P	(9.32%)	6.29%	11.59%
After Taxes on Distributions and Sale of Fund Shares | CLASS P	(5.14%)	5.13%	9.89%
S&P 500 Index	(4.38%)	8.49%	13.12%

[1] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[1] "Other expenses" include "Acquired fund fees and expenses," which were less than 0.01% of the average net assets of the Fund.

[2] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses), through the period ending October 28, 2020, do not exceed 0.95% for Class A shares and 0.70% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

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UBS Global Allocation Fund

UBS Global Allocation Fund

Investment objective

The Fund seeks to maximize total return, consisting of capital appreciation and current income.

Fees and expenses

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder fees (fees paid directly from your investment)

Shareholder Fees - UBS Global Allocation Fund	CLASS A		CLASS P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	5.50%		none
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	none	[1]	none

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - UBS Global Allocation Fund		CLASS A	CLASS P
Management fees		0.80%	0.80%
Distribution and/or service (12b-1) fees		0.25%	none
Other expenses		0.35%	0.33%
Acquired fund fees and expenses		0.07%	0.07%
Total annual fund operating expenses	[1]	1.47%	1.20%
Less management fee waiver/expense reimbursements	[2]	0.20%	0.18%
Total annual fund operating expenses after management fee waiver/expense reimbursements	[1],[2]	1.27%	1.02%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first fiscal year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example - UBS Global Allocation Fund - USD ($)	1 year	3 years	5 years	10 years
CLASS A	672	971	1,291	2,195
CLASS P	104	363	642	1,439

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 35% of the average value of its portfolio.

Principal strategies

Principal investments

In order to achieve the Fund's objective, the Fund employs an asset allocation strategy that seeks to maximize total return. The Fund's investment advisor ("UBS AM (Americas)" or the "Advisor") does not represent or guarantee that the Fund will meet this total return goal.

Under normal circumstances, the Fund will invest in securities and derivatives to gain exposure to equity, fixed income, and alternative asset class securities, including, but not limited to, convertible bonds and real estate securities, including real estate investment trusts ("REITs") and real estate operating companies. The Fund may gain exposure to issuers located within and outside the United States, including securities of issuers in both developed (including the United States) and emerging markets countries.

Investments in fixed income securities may include, but are not limited to, debt securities of governments throughout the world (including the United States), their agencies and instrumentalities, debt securities of corporations, mortgage-backed securities and asset-backed securities.The Fund may invest in securities of any maturity greater than one year and such securities may be either investment grade or high yield (lower-rated or "junk bonds") securities. Investments in equity securities may include, but are not limited to, common stock and preferred stock. The Fund may invest in other open-end investment companies advised by the Advisor and third-party passively managed exchanged-traded funds ("ETFs") to gain exposure to certain asset classes. The Fund may also take active positions on volatility to generate returns or to hedge the Fund's portfolio.

The Fund may, but is not required to, use exchange-traded or over-the-counter derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include index options, futures, forward agreements, swap agreements (including, interest rate, credit default and inflation swaps), equity participation notes and equity linked notes. All of these derivatives may be used for risk management purposes, such as hedging against a specific security or currency (except with respect to equity participation notes and equity linked notes), or to manage or adjust the risk profile of the Fund. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments; to obtain exposure to certain markets; or to establish net short positions for individual markets, currencies or securities. Futures on indices, forward agreements, interest rate swaps and credit default swaps may also be used to adjust the Fund's portfolio duration.

Under certain market conditions, the Fund may invest in companies at the time of their initial public offering ("IPO").

Management process

The Advisor will manage the Fund's portfolio using the following investment process as described below:

The strategy invests in the full spectrum of instruments and markets globally. The Advisor believes that the Advisor is able to improve the return outcome and risk management of the Fund by employing a well diversified strategy across a broad global opportunity set. Returns are generated from asset allocation across markets, currency and security selection.

Asset allocation decisions are primarily driven by UBS AM (Americas)'s assessment of valuation and prevailing market conditions in the United States and around the world. Using a systematic approach, the portfolio management team analyzes the asset classes and investments across equities, fixed income, and alternative asset classes (including currency), considering both fundamental valuation, economic and other market indicators. Regarding valuation, the Advisor evaluates whether asset classes and investments are attractively priced relative to fundamentals. The starting point is to assess the intrinsic value of an asset class, as determined by the fundamentals that drive an asset class' future cash flow. The intrinsic value represents a long term anchor point to which the Advisor believes the asset class will eventually revert.

Fair value estimates of asset classes and markets are an output of UBS AM (Americas)'s proprietary valuation models. Discounting the asset's future cash flow using a discount rate that appropriately reflects the inherent investment risk associated with holding the asset gives the asset's fair value. The competitive advantage of the Advisor's models lies in the quality and consistency of the inputs used and, therefore, the reliability of valuation conclusions. The discrepancy between actual market level and fair value (the price/value discrepancy) is the primary valuation signal used in identifying investment opportunities.

Next, the Advisor assesses additional market indicators and considers the effect that other determinants of economic growth and overall market volatility will have on each asset class. While in theory price/value discrepancies may resolve themselves quickly and linearly, in practice price/value discrepancy can grow larger before it resolves. While valuation models have proven effective at identifying longer-term price/value discrepancies, in the shorter term other factors can swamp valuation considerations. Thus, the Advisor incorporates an additional discipline in our idea generation process. The Advisor refers to this additional step in its idea generation process as market behavior analysis. Adding this step helps the Advisor to understand what other market indicators might drive the market towards or away from fundamental value. The Advisor performs systematic analysis of non-valuation drivers using models measuring sentiment, momentum and flows, market stress, the stage of the economic cycle, as well as an assessment of the general macroeconomic landscape. Conversely, valuation considerations tend to dominate when an asset class is substantially above or below fair value, but the Advisor recognizes that the use of market behavior analysis during these periods is very important to helping improve the timing in and out of these asset classes with very stretched valuations.

The asset allocation process is structured around the Investment Solutions Investment Committee (the "ISIC Committee") meetings, which provides a forum for debate and the exploration of all ramifications of any investment decision, rather than aiming for a consensus to be reached. Instead, any voting member of the ISIC Committee can sponsor a trade idea, preparing a detailed investment thesis to support the view. An investment thesis has to define the investment rationale based on valuation and market behavioral influences, the time scale for it being realized, the transaction costs and the potential milestones the Advisor would expect to evaluate whether or not the view is correct. The sponsor is then responsible for convincing another member of the ISIC Committee to support the idea as co-sponsor.

Bottom up selection across active equity and fixed income markets can be utilized as part of the asset allocation process at the asset class level. With respect to specific equity securities for inclusion in the Fund's equity asset classes, the Advisor may utilize fundamental valuation, quantitative and growth-oriented strategies. The Advisor's bottom up fixed income security selection strategy combines judgments about the absolute value of the fixed income universe and the relative value of issuer sectors, maturity intervals, security durations, credit qualities and coupon segments, as well as specific circumstances facing the issuers of fixed income securities.

The Advisor uses both fundamental valuation and market behavior analysis to make the two-pronged determination of risk budget and risk allocation. The Advisor works closely with the Risk Management team, members of which attend the ISIC Committee meetings, to determine the appropriate amount of risk capital to allocate to the underlying trade ideas given the strategy's risk budget and objectives, prevailing investment opportunities, and other strategy exposures. To assist in this process the Risk Management team performs scenario and correlation analysis to better understand the risk and diversification of the overall strategy, and attempts to ensure that unintended factor exposures are identified, managed and monitored.

Main risks

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Investments in foreign government bonds involve special risks because the Fund may have limited legal recourse in the event of default. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Asset allocation risk: The risk that the Fund may allocate assets to an asset category that performs poorly relative to other asset categories.

Interest rate risk: An increase in prevailing interest rates typically causes the value of fixed income securities to fall. Changes in interest rates will likely affect the value of longer-duration fixed income securities more than shorter-duration securities and higher quality securities more than lower quality securities. When interest rates are falling, some fixed income securities provide that the issuer may repay them earlier than the maturity date, and if this occurs the Fund may have to reinvest these repayments at lower interest rates. The Fund may face a heightened level of interest rate risk due to certain changes in monetary policy, such as certain types of interest rate changes by the Federal Reserve.

Credit risk: The risk that the Fund could lose money if the issuer or guarantor of a fixed income security, or the counterparty to or guarantor of a derivative contract, is unable or unwilling to meet its financial obligations. This risk is likely greater for lower quality investments than for investments that are higher quality.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

High yield bond risk: The risk that the issuer of bonds with ratings of Ba1 or lower by Moody's Investors Service, Inc. ("Moody's") or BB+ or lower by Standard & Poor's Financial Services LLC ("S&P") or Fitch Ratings, Inc. ("Fitch"), comparably rated by another nationally recognized statistical rating organization, or, if unrated, are determined to be of comparable quality by the Advisor, will default or otherwise be unable to honor a financial obligation (also known as lower-rated or "junk bonds"). These securities are considered to be predominately speculative with respect to an issuer's capacity to pay interest and repay principal in accordance with the terms of the obligations. Lower-quality bonds are more likely to be subject to an issuer's default or downgrade than investment grade (higher quality) bonds.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Mortgage- and asset-backed securities risk: The Fund may invest in mortgage- and asset-backed securities that are subject to prepayment or call risk, which is the risk that the borrower's payments may be received earlier or later than expected due to changes in prepayment rates on underlying loans. Faster prepayments often happen when interest rates are falling. As a result, the Fund may reinvest these early payments at lower interest rates, thereby reducing the Fund's income. Conversely, when interest rates rise, prepayments may happen more slowly, causing the security to lengthen in duration. Longer duration securities tend to be more volatile. Securities may be prepaid at a price less than the original purchase value. An unexpectedly high rate of defaults on the mortgages held by a mortgage pool may adversely affect the value of mortgage-backed securities and could result in losses to the Fund.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments, and they may have more limited resources.

US Government securities risk: There are different types of US government securities with different levels of credit risk, including risk of default, depending on the nature of the particular government support for that security. For example, a US government-sponsored entity, although chartered or sponsored by an Act of Congress, may issue securities that are neither insured nor guaranteed by the US Treasury and are therefore riskier than those that are.

IPOs risk: The purchase of shares issued in IPOs may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time.

Market risk: The risk that the market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market securities.

Derivatives relating to fixed income markets are especially susceptible to interest rate risk and credit risk. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in other funds risk: The Fund's investment performance is affected by the investment performance of the underlying funds in which the Fund may invest, including ETFs. Through its investment in the underlying funds, the Fund is subject to the risks of the underlying funds' investments and subject to the underlying funds' expenses.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Performance

Risk/return bar chart and table

The performance information that follows shows the Fund's performance information in a bar chart and an average annual total returns table. The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance. The MSCI All Country World Index (net) shows how the Fund's performance compares to an index that is designed to measure the equity market performance of developed and emerging markets. The FTSE World Government Bond Index (Hedged in USD) shows how the Fund's performance compares to an index composed of straight (i.e., not floating rate or index-linked) government bonds with a one-year minimum maturity that is hedged back to the US dollar. The Fund's secondary benchmark index is a blend of 60% MSCI All Country World Index (net)/40% FTSE World Government Bond Index (Hedged in USD) and shows how the Fund's performance compares with a blend of prominent industry indices that better reflect the asset allocation of the Fund's portfolio. Indices reflect no deduction for fees, expenses or taxes, except for the MSCI All Country World Index (net) which reflects no deduction for fees and expenses. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Updated performance for the Fund is available at www.ubs.com/us-mutualfundperformance.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Total return (Class P)

Total return January 1 - September 30, 2019: 12.01%
Best quarter during calendar years shown—2Q 2009: 23.56%
Worst quarter during calendar years shown—3Q 2011: (13.45)%

Average annual total returns (figures reflect sales charges) (for the periods ended December 31, 2018)

Average Annual Returns - UBS Global Allocation Fund	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years	Average Annual Returns, Inception Date
CLASS A	(12.81%)	1.44%	6.39%	Jun. 30, 1997
CLASS P	(7.56%)	2.86%	7.29%	Aug. 31, 1992
After Taxes on Distributions | CLASS P	(7.56%)	2.38%	6.40%
After Taxes on Distributions and Sale of Fund Shares | CLASS P	(4.48%)	2.04%	5.59%
MSCI All Country World Index (net)	(9.41%)	4.26%	9.46%
FTSE World Government Bond Index (Hedged in USD)	2.60%	3.60%	3.25%
60% MSCI All Country World Index (net)/40% FTSE World Government Bond Index (Hedged in USD)	(4.53%)	4.17%	7.24%

[1] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[1] Since the "Acquired fund fees and expenses" are not directly borne by the Fund, they are not reflected in the Fund's financial statements, and therefore the amounts listed in "Total annual fund operating expenses" will differ from those presented in the Financial highlights.

[2] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, and extraordinary expenses to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, and extraordinary expenses), through the period ending October 28, 2020, do not exceed 1.20% for Class A shares and 0.95% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

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UBS International Sustainable Equity Fund

UBS International Sustainable Equity Fund

Investment objective

The Fund seeks to maximize total return, consisting of capital appreciation and current income by investing primarily in the equity securities of non-US issuers.

Fees and expenses

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder fees (fees paid directly from your investment)

Shareholder Fees - UBS International Sustainable Equity Fund	CLASS A		CLASS P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	5.50%		none
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	none	[1]	none

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - UBS International Sustainable Equity Fund		CLASS A	CLASS P
Management fees		0.80%	0.80%
Distribution and/or service (12b-1) fees		0.25%	none
Other expenses	[1]	0.48%	0.46%
Total annual fund operating expenses		1.53%	1.26%
Less management fee waiver/expense reimbursements	[2]	0.28%	0.26%
Total annual fund operating expenses after management fee waiver/expense reimbursements	[2]	1.25%	1.00%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the irrevocable fee waiver and expense reimbursement for all years. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example - UBS International Sustainable Equity Fund - USD ($)	1 year	3 years	5 years	10 years
CLASS A	670	925	1,199	1,978
CLASS P	102	318	552	1,225

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 57% of the average value of its portfolio.

Principal strategies

Principal investments

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in equity securities. Investments in equity securities may include, but are not limited to, dividend-paying securities, common stock and preferred stock of issuers located throughout the world; equity securities of real estate investment trusts ("REITs"); and exchange-traded funds ("ETFs"). Under normal market conditions, the Fund invests primarily (at least 65% of its total assets) in issuers organized or having their principal place of business outside the United States or doing a substantial amount of business outside the United States. Up to 35% of the Fund's assets may be invested in US equity securities. The Fund may invest in issuers from both developed and emerging markets. The Advisor, on behalf of the Fund, intends to diversify broadly among countries, but reserves the right to invest a substantial portion of the Fund's assets in one or more countries if economic and business conditions warrant such investments. The Fund may invest in stocks of companies of any size.

The Fund may, but is not required to, use exchange-traded or over-the-counter ("OTC") derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include futures, forward currency agreements and equity participation notes. All of these derivatives may be used for risk management purposes to manage or adjust the risk profile of the Fund. Futures on currencies and forward currency agreements may also be used to hedge against a specific currency. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments (except for forward currency agreements); or to obtain exposure to certain markets (except for forward currency agreements). The Fund also may use futures contracts on equity securities and indices to gain market exposure on its uninvested cash.

Under certain market conditions, the Fund may invest in companies at the time of their initial public offering ("IPO").

Management process

The Advisor's investment decisions are based upon price/value discrepancies as identified by the Advisor's fundamental valuation process.

In selecting securities for the portion of the Fund that is managed according to the Advisor's fundamental valuation process, the Advisor focuses on, among other things, identifying discrepancies between a security's fundamental value and its market price. In this context, the fundamental value of a given security is the Advisor's assessment of what a security is worth. The Advisor will select a security whose fundamental value it estimates to be greater than its market value at any given time. For each stock under analysis, the Advisor bases its estimates of value upon country, economic, industry and company analysis, as well as upon a company's management team, competitive advantage and core competencies. The Advisor then compares its assessment of a security's value against the prevailing market prices, with the aim of constructing a portfolio of stocks across industries and countries with attractive relative price/value characteristics.

The Advisor will employ both a positive and negative screening process with regard to securities selection for the Fund. The negative screening process will exclude securities with more than 5% of sales in alcohol, tobacco, defense, nuclear, GMO (Genetically Modified Organisms), gambling and pornography from the Fund's portfolio. We believe that this negative screen reduces the global universe by about 7% by market capitalization, and we do not expect it to have a material impact on portfolio construction or strategy. The Advisor may modify the above list of negative screens at any time, without prior shareholder approval or notice.

The positive screening process will identify securities of companies that are attractive based on their fundamental and valuation profile in addition to evaluating specific sustainability factors.

These sustainability factors are material factors that help the Advisor evaluate and compare the environmental, social and governance performance of the investable universe. This information is combined with additional financial analysis and research to identify companies the Advisor believes will provide attractively valued and sustainable investment opportunities.

Main risks

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

Sustainability factor risk: The Fund's sustainability factors used in its investment process will likely make the Fund perform differently from a fund that relies solely or primarily on financial metrics. The sustainability factors may cause the Fund's industry allocation to deviate from that of funds without these considerations.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments, and they may have more limited resources.

IPOs risk: The purchase of shares issued in IPOs may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market securities. In addition, non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Performance

Risk/return bar chart and table

The performance information that follows shows the Fund's performance information in a bar chart and an average annual total returns table. The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance. Indicies reflect no deduction for fees and expenses. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. In October 2013, the Fund's investment strategies changed. The performance below for periods prior to that date is attributable to the Fund's performance before the strategy change. Updated performance for the Fund is available at www.ubs.com/us-mutualfundperformance.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Total return (Class P)

Total return January 1 - September 30, 2019: 11.17%
Best quarter during calendar years shown—2Q 2009: 29.94%
Worst quarter during calendar years shown—3Q 2011: (23.88)%

Average annual total returns (figures reflect sales charges) (for the periods ended December 31, 2018)

Average Annual Returns - UBS International Sustainable Equity Fund		Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years	Average Annual Returns, Inception Date
CLASS A		(21.48%)	1.06%	6.35%	Jun. 30, 1997
CLASS P		(16.71%)	2.47%	7.21%	Aug. 31, 1993
After Taxes on Distributions | CLASS P		(16.98%)	2.17%	6.66%
After Taxes on Distributions and Sale of Fund Shares | CLASS P		(9.49%)	2.01%	5.87%
MSCI ACWI ex-US Index	[1]	(14.20%)	0.68%	6.57%
MSCI World ex USA Index (net)	[1]	(14.09%)	0.34%	6.24%

[1] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[1] "Other expenses" include "Acquired fund fees and expenses," which were less than 0.01% of the average net assets of the Fund.

[2] UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), has agreed irrevocably to waive its fees and reimburse certain expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) do not exceed 1.25% for Class A shares and 1.00% for Class P shares. This fee waiver and expense arrangement may only be amended or terminated by shareholders.

[1] Effective October 28, 2019, the MSCI ACWI ex-US Index replaced MSCI World ex USA Index (net) as the Fund's primary benchmark because it more closely aligns with the Fund's investment strategy.

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Label

Element

Value

UBS Municipal Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

UBS Municipal Bond Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide total return consisting of capital appreciation and current income exempt from federal income tax.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $100,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Oct. 28, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as mark-ups, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 31% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

31.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $100,000 in the Fund.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 100,000

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal strategies

Strategy Narrative [Text Block]

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Principal investments

Under normal circumstances, the Fund will invest at least 80% of its net assets (plus borrowings for investment purposes, if any) in municipal bonds and other investments with similar economic characteristics, the interest on which is exempt from regular federal income tax. The Fund primarily invests in securities that, at the time of purchase, are rated investment grade by an independent rating agency (or if unrated are deemed to be of comparable quality by the Advisor), but may invest up to 10% in securities rated below investment grade (also known as "junk bonds"). The Fund may also, to a lesser extent, invest in US Treasury securities and other securities of the US government, its agencies and government-sponsored enterprises. The Fund is a non-diversified fund, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company.

The Fund's weighted average portfolio duration will normally range between 3 and 10 years, but the Fund generally targets a duration of between 4.5 and 7 years. The Fund may invest in bonds of any maturity or duration.

The Fund may invest in insured and uninsured municipal securities. The Fund's investments may include, but are not limited to, general obligation and revenue bonds, tax-exempt commercial paper, short-term municipal notes, tender option bonds (including inverse floaters), floating and variable rate demand obligations, and other municipal securities that pay income exempt from federal income tax. The Fund does not intend to invest substantially in securities whose interest is subject to the federal alternative minimum tax.

The Fund may, but is not required to, use exchange traded or over-the-counter ("OTC") derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include interest rate and credit instruments such as options (including, options on futures and swap agreements), futures, swap agreements (including, interest rate, total return, and credit default swaps), credit-linked securities and structured investments. All of these derivatives may be used for risk management purposes, such as hedging against a specific security, or to manage or adjust the risk profile of the Fund. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments; to obtain exposure to certain markets; to establish net short positions for individual sectors, markets or securities; or to adjust the Fund's portfolio duration.

The Fund may invest in exchange-traded funds ("ETFs") to gain exposure to certain asset classes.

Management process

The Advisor adheres to a disciplined top-down and bottom-up investment process that seeks to leverage information advantage by using a proprietary credit research framework while focusing on three key decisions: duration, sector allocation and security selection. The investment process begins with an in-depth analysis of top-down inputs to determine the correct duration positioning of the portfolio. These inputs originate from the Advisor's proprietary research on the structure of the yield curve and its relationship to the US Treasury market. The Advisor's sector allocation analysis determines the attractiveness of various segments of the municipal market with a focus on two main themes—bond security (e.g., state vs. local general obligation bonds) and essential services (e.g., water and sewer systems or electric utilities). Security selection represents the final level of decision-making in the Advisor's investment process. The Advisor uses rigorous credit/structure analysis and relative pricing to select securities that the Advisor believes demonstrate superior risk/return characteristics. The Advisor then seeks to select individual securities that will provide the portfolio the desired sector and duration exposures at the lowest cost.

Risk [Heading]

rr_RiskHeading

Main risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Municipal securities risk: Municipal securities are subject to interest rate and credit risks. The ability of a municipal issuer to make payments and the value of municipal securities can be affected by uncertainties in the municipal securities market. Such uncertainties could cause increased volatility in the municipal securities market and could negatively impact the fund's net asset value and/or the distributions paid by the fund. Municipal bonds secured by revenues from public housing authorities may be subject to additional uncertainties relating to the possibility that proceeds may exceed supply of available mortgages to be purchased by public housing authorities, resulting in early retirement of bonds, or that homeowner repayments will create an irregular cash flow. Municipalities continue to experience difficulties in the current economic and political environment.

Interest rate risk: An increase in prevailing interest rates typically causes the value of fixed income securities to fall. Changes in interest rates will likely affect the value of longer-duration fixed income securities more than shorter-duration securities and higher quality securities more than lower quality securities. When interest rates are falling, some fixed income securities provide that the issuer may repay them earlier than the maturity date, and if this occurs the Fund may have to reinvest these repayments at lower interest rates. The Fund may face a heightened level of interest rate risk due to certain changes in monetary policy, such as certain types of interest rate changes by the Federal Reserve.

Credit risk: The risk that the Fund could lose money if the issuer or guarantor of a fixed income security, or the counterparty to or guarantor of a derivative contract, is unable or unwilling to meet its financial obligations. This risk is likely greater for lower quality investments than for investments that are higher quality.

Prepayment or call risk: The risk that issuers will prepay fixed rate obligations when interest rates fall, forcing the Fund to reinvest in obligations with lower interest rates than the original obligations. When interest rates are rising, slower prepayments may extend the duration of the securities and may reduce their value.

Political risk: The Fund's investments may be significantly affected by political changes, including legislative proposals that may make municipal bonds less attractive in comparison to taxable bonds or other types of investments.

Tax liability risk: Tax liability risk is the risk of noncompliant conduct by a municipal bond issuer, resulting in distributions by the Fund being taxable to shareholders as ordinary income.

Related securities concentration risk: Because the Fund may invest more than 25% of its net assets in municipal bonds that are issued to finance similar projects, economic, business, or political developments or changes that affect one municipal bond also may affect other municipal bonds in the same sector.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Variable rate demand obligations risk: Variable rate demand obligations are floating rate securities that combine an interest in a long-term municipal bond with a right to demand payment before maturity from a bank or other financial institution. If the bank or financial institution is unable to pay, the Fund may lose money. The absence of an active secondary market for certain variable and floating rate obligations could make it difficult to dispose of these instruments, which could result in a loss.

US Government securities risk: There are different types of US government securities with different levels of credit risk, including risk of default, depending on the nature of the particular government support for that security. For example, a US government-sponsored entity, although chartered or sponsored by an Act of Congress, may issue securities that are neither insured nor guaranteed by the US Treasury and are therefore riskier than those that are.

High yield bond risk: The risk that the issuer of municipal bonds with ratings of Ba1 or lower by Moody's Investors Service, Inc. ("Moody's") or BB+ or lower by Standard & Poor's Financial Services LLC ("S&P") or Fitch Ratings, Inc. ("Fitch"), comparably rated by another nationally recognized statistical rating organization, or, if unrated, are determined to be of comparable quality by the Advisor, will default or otherwise be unable to honor a financial obligation (also known as lower-rated or "junk bonds"). These securities are considered to be predominately speculative with respect to an issuer's capacity to pay interest and repay principal in accordance with the terms of the obligations. Lower-rated municipal bonds are more likely to be subject to an issuer's default or downgrade than investment grade (higher quality) municipal bonds.

Non-diversification risk: The Fund is a non-diversified investment company, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company. As a non-diversified fund, the Fund's share price may be more volatile and the Fund has a greater potential to realize losses upon the occurrence of adverse events affecting a particular issuer.

Market risk: The risk that the market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market securities.

Derivatives relating to fixed income markets are especially susceptible to interest rate risk and credit risk. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose money by investing in the Fund.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The Fund is a non-diversified investment company, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company. As a non-diversified fund, the Fund's share price may be more volatile and the Fund has a greater potential to realize losses upon the occurrence of adverse events affecting a particular issuer.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

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Performance

Performance Narrative [Text Block]

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Risk/return bar chart and table

The performance information that follows shows the Fund's performance information in a bar chart and an average annual total returns table. The information provides some indication of the risks of investing in the Fund by showing the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance. The Bloomberg Barclays Municipal Bond Index shows how the Fund's performance compares to an index that is designed to measure the fixed income market performance of the tax-exempt bond market. The Bloomberg Barclays Municipal Managed Money Intermediate (1-17) Index compares the Fund's performance to an index that measures the performance of municipal securities issued by state and local municipalities whose interest is exempt from both federal income tax and the federal alternative minimum tax. Indices reflect no deduction for fees, expenses or taxes. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Updated performance for the Fund is available at www.ubs.com/us-mutualfundperformance.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information provides some indication of the risks of investing in the Fund by showing the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.ubs.com/us-mutualfundperformance

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

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Total return (Class P)*

Bar Chart Footnotes [Text Block]

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* 2015 is the Fund's first full year of operations.

Bar Chart Closing [Text Block]

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Total return January 1 - September 30, 2019: 7.27%
Best quarter during calendar year shown—2Q 2016: 2.38%
Worst quarter during calendar year shown—4Q 2016: (3.44)%

Year to Date Return, Label

rr_YearToDateReturnLabel

Total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

7.27%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2016

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

2.38%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2016

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(3.44%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

Indices reflect no deduction for fees, expenses or taxes.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

Average annual total returns (figures reflect sales charges) (for the periods ended December 31, 2018)

UBS Municipal Bond Fund | Bloomberg Barclays Municipal Bond Index

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

1.28%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

2.70%

UBS Municipal Bond Fund | Bloomberg Barclays Municipal Managed Money Intermediate (1-17) Index

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

1.22%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

2.40%

UBS Municipal Bond Fund | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

2.25%

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Management fees

rr_ManagementFeesOverAssets

0.40%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.42%

^[2]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.07%

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

0.42%

^[3]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

0.65%

^[3]

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Purchases of $500,000 or more that were not subject to a front-end sales charge are subject to a 0.75% CDSC if sold within one year of the purchase date.

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 290

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

517

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

762

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,464

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(1.58%)

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

1.47%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 10, 2014

UBS Municipal Bond Fund | Class P

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.40%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.42%

^[2]

Total annual fund operating expenses

rr_ExpensesOverAssets

0.82%

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

0.42%

^[3]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

0.40%

^[3]

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 41

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

220

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

414

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 974

Annual Return 2015

rr_AnnualReturn2015

3.10%

Annual Return 2016

rr_AnnualReturn2016

0.25%

Annual Return 2017

rr_AnnualReturn2017

4.18%

Annual Return 2018

rr_AnnualReturn2018

0.98%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.98%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

2.26%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 10, 2014

UBS Municipal Bond Fund | Class P | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.98%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

2.24%

UBS Municipal Bond Fund | Class P | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

1.37%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

2.16%

[1] Purchases of $500,000 or more that were not subject to a front-end sales charge are subject to a 0.75% CDSC if sold within one year of the purchase date.

[2] "Other expenses" include "Acquired fund fees and expenses," which were less than 0.01% of the average net assets of the Fund.

[3] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses), through the period ending October 28, 2020, do not exceed 0.65% for Class A shares and 0.40% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement, or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

XML

Label

Element

Value

UBS Global Allocation Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

UBS Global Allocation Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to maximize total return, consisting of capital appreciation and current income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Oct. 28, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 35% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

35.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 50,000

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Since the "Acquired fund fees and expenses" are not directly borne by the Fund, they are not reflected in the Fund's financial statements, and therefore the amounts listed in "Total annual fund operating expenses" will differ from those presented in the Financial highlights.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first fiscal year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Principal investments

In order to achieve the Fund's objective, the Fund employs an asset allocation strategy that seeks to maximize total return. The Fund's investment advisor ("UBS AM (Americas)" or the "Advisor") does not represent or guarantee that the Fund will meet this total return goal.

Under normal circumstances, the Fund will invest in securities and derivatives to gain exposure to equity, fixed income, and alternative asset class securities, including, but not limited to, convertible bonds and real estate securities, including real estate investment trusts ("REITs") and real estate operating companies. The Fund may gain exposure to issuers located within and outside the United States, including securities of issuers in both developed (including the United States) and emerging markets countries.

Investments in fixed income securities may include, but are not limited to, debt securities of governments throughout the world (including the United States), their agencies and instrumentalities, debt securities of corporations, mortgage-backed securities and asset-backed securities.The Fund may invest in securities of any maturity greater than one year and such securities may be either investment grade or high yield (lower-rated or "junk bonds") securities. Investments in equity securities may include, but are not limited to, common stock and preferred stock. The Fund may invest in other open-end investment companies advised by the Advisor and third-party passively managed exchanged-traded funds ("ETFs") to gain exposure to certain asset classes. The Fund may also take active positions on volatility to generate returns or to hedge the Fund's portfolio.

The Fund may, but is not required to, use exchange-traded or over-the-counter derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include index options, futures, forward agreements, swap agreements (including, interest rate, credit default and inflation swaps), equity participation notes and equity linked notes. All of these derivatives may be used for risk management purposes, such as hedging against a specific security or currency (except with respect to equity participation notes and equity linked notes), or to manage or adjust the risk profile of the Fund. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments; to obtain exposure to certain markets; or to establish net short positions for individual markets, currencies or securities. Futures on indices, forward agreements, interest rate swaps and credit default swaps may also be used to adjust the Fund's portfolio duration.

Under certain market conditions, the Fund may invest in companies at the time of their initial public offering ("IPO").

Management process

The Advisor will manage the Fund's portfolio using the following investment process as described below:

The strategy invests in the full spectrum of instruments and markets globally. The Advisor believes that the Advisor is able to improve the return outcome and risk management of the Fund by employing a well diversified strategy across a broad global opportunity set. Returns are generated from asset allocation across markets, currency and security selection.

Asset allocation decisions are primarily driven by UBS AM (Americas)'s assessment of valuation and prevailing market conditions in the United States and around the world. Using a systematic approach, the portfolio management team analyzes the asset classes and investments across equities, fixed income, and alternative asset classes (including currency), considering both fundamental valuation, economic and other market indicators. Regarding valuation, the Advisor evaluates whether asset classes and investments are attractively priced relative to fundamentals. The starting point is to assess the intrinsic value of an asset class, as determined by the fundamentals that drive an asset class' future cash flow. The intrinsic value represents a long term anchor point to which the Advisor believes the asset class will eventually revert.

Fair value estimates of asset classes and markets are an output of UBS AM (Americas)'s proprietary valuation models. Discounting the asset's future cash flow using a discount rate that appropriately reflects the inherent investment risk associated with holding the asset gives the asset's fair value. The competitive advantage of the Advisor's models lies in the quality and consistency of the inputs used and, therefore, the reliability of valuation conclusions. The discrepancy between actual market level and fair value (the price/value discrepancy) is the primary valuation signal used in identifying investment opportunities.

Next, the Advisor assesses additional market indicators and considers the effect that other determinants of economic growth and overall market volatility will have on each asset class. While in theory price/value discrepancies may resolve themselves quickly and linearly, in practice price/value discrepancy can grow larger before it resolves. While valuation models have proven effective at identifying longer-term price/value discrepancies, in the shorter term other factors can swamp valuation considerations. Thus, the Advisor incorporates an additional discipline in our idea generation process. The Advisor refers to this additional step in its idea generation process as market behavior analysis. Adding this step helps the Advisor to understand what other market indicators might drive the market towards or away from fundamental value. The Advisor performs systematic analysis of non-valuation drivers using models measuring sentiment, momentum and flows, market stress, the stage of the economic cycle, as well as an assessment of the general macroeconomic landscape. Conversely, valuation considerations tend to dominate when an asset class is substantially above or below fair value, but the Advisor recognizes that the use of market behavior analysis during these periods is very important to helping improve the timing in and out of these asset classes with very stretched valuations.

The asset allocation process is structured around the Investment Solutions Investment Committee (the "ISIC Committee") meetings, which provides a forum for debate and the exploration of all ramifications of any investment decision, rather than aiming for a consensus to be reached. Instead, any voting member of the ISIC Committee can sponsor a trade idea, preparing a detailed investment thesis to support the view. An investment thesis has to define the investment rationale based on valuation and market behavioral influences, the time scale for it being realized, the transaction costs and the potential milestones the Advisor would expect to evaluate whether or not the view is correct. The sponsor is then responsible for convincing another member of the ISIC Committee to support the idea as co-sponsor.

Bottom up selection across active equity and fixed income markets can be utilized as part of the asset allocation process at the asset class level. With respect to specific equity securities for inclusion in the Fund's equity asset classes, the Advisor may utilize fundamental valuation, quantitative and growth-oriented strategies. The Advisor's bottom up fixed income security selection strategy combines judgments about the absolute value of the fixed income universe and the relative value of issuer sectors, maturity intervals, security durations, credit qualities and coupon segments, as well as specific circumstances facing the issuers of fixed income securities.

The Advisor uses both fundamental valuation and market behavior analysis to make the two-pronged determination of risk budget and risk allocation. The Advisor works closely with the Risk Management team, members of which attend the ISIC Committee meetings, to determine the appropriate amount of risk capital to allocate to the underlying trade ideas given the strategy's risk budget and objectives, prevailing investment opportunities, and other strategy exposures. To assist in this process the Risk Management team performs scenario and correlation analysis to better understand the risk and diversification of the overall strategy, and attempts to ensure that unintended factor exposures are identified, managed and monitored.

Risk [Heading]

rr_RiskHeading

Main risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Investments in foreign government bonds involve special risks because the Fund may have limited legal recourse in the event of default. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Asset allocation risk: The risk that the Fund may allocate assets to an asset category that performs poorly relative to other asset categories.

Interest rate risk: An increase in prevailing interest rates typically causes the value of fixed income securities to fall. Changes in interest rates will likely affect the value of longer-duration fixed income securities more than shorter-duration securities and higher quality securities more than lower quality securities. When interest rates are falling, some fixed income securities provide that the issuer may repay them earlier than the maturity date, and if this occurs the Fund may have to reinvest these repayments at lower interest rates. The Fund may face a heightened level of interest rate risk due to certain changes in monetary policy, such as certain types of interest rate changes by the Federal Reserve.

Credit risk: The risk that the Fund could lose money if the issuer or guarantor of a fixed income security, or the counterparty to or guarantor of a derivative contract, is unable or unwilling to meet its financial obligations. This risk is likely greater for lower quality investments than for investments that are higher quality.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

High yield bond risk: The risk that the issuer of bonds with ratings of Ba1 or lower by Moody's Investors Service, Inc. ("Moody's") or BB+ or lower by Standard & Poor's Financial Services LLC ("S&P") or Fitch Ratings, Inc. ("Fitch"), comparably rated by another nationally recognized statistical rating organization, or, if unrated, are determined to be of comparable quality by the Advisor, will default or otherwise be unable to honor a financial obligation (also known as lower-rated or "junk bonds"). These securities are considered to be predominately speculative with respect to an issuer's capacity to pay interest and repay principal in accordance with the terms of the obligations. Lower-quality bonds are more likely to be subject to an issuer's default or downgrade than investment grade (higher quality) bonds.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Mortgage- and asset-backed securities risk: The Fund may invest in mortgage- and asset-backed securities that are subject to prepayment or call risk, which is the risk that the borrower's payments may be received earlier or later than expected due to changes in prepayment rates on underlying loans. Faster prepayments often happen when interest rates are falling. As a result, the Fund may reinvest these early payments at lower interest rates, thereby reducing the Fund's income. Conversely, when interest rates rise, prepayments may happen more slowly, causing the security to lengthen in duration. Longer duration securities tend to be more volatile. Securities may be prepaid at a price less than the original purchase value. An unexpectedly high rate of defaults on the mortgages held by a mortgage pool may adversely affect the value of mortgage-backed securities and could result in losses to the Fund.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments, and they may have more limited resources.

US Government securities risk: There are different types of US government securities with different levels of credit risk, including risk of default, depending on the nature of the particular government support for that security. For example, a US government-sponsored entity, although chartered or sponsored by an Act of Congress, may issue securities that are neither insured nor guaranteed by the US Treasury and are therefore riskier than those that are.

IPOs risk: The purchase of shares issued in IPOs may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time.

Market risk: The risk that the market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market securities.

Derivatives relating to fixed income markets are especially susceptible to interest rate risk and credit risk. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in other funds risk: The Fund's investment performance is affected by the investment performance of the underlying funds in which the Fund may invest, including ETFs. Through its investment in the underlying funds, the Fund is subject to the risks of the underlying funds' investments and subject to the underlying funds' expenses.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

Risk/return bar chart and table

The performance information that follows shows the Fund's performance information in a bar chart and an average annual total returns table. The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance. The MSCI All Country World Index (net) shows how the Fund's performance compares to an index that is designed to measure the equity market performance of developed and emerging markets. The FTSE World Government Bond Index (Hedged in USD) shows how the Fund's performance compares to an index composed of straight (i.e., not floating rate or index-linked) government bonds with a one-year minimum maturity that is hedged back to the US dollar. The Fund's secondary benchmark index is a blend of 60% MSCI All Country World Index (net)/40% FTSE World Government Bond Index (Hedged in USD) and shows how the Fund's performance compares with a blend of prominent industry indices that better reflect the asset allocation of the Fund's portfolio. Indices reflect no deduction for fees, expenses or taxes, except for the MSCI All Country World Index (net) which reflects no deduction for fees and expenses. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Updated performance for the Fund is available at www.ubs.com/us-mutualfundperformance.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

The Fund's secondary benchmark index is a blend of 60% MSCI All Country World Index (net)/40% FTSE World Government Bond Index (Hedged in USD) and shows how the Fund's performance compares with a blend of prominent industry indices that better reflect the asset allocation of the Fund's portfolio

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.ubs.com/us-mutualfundperformance

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total return (Class P)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Total return January 1 - September 30, 2019: 12.01%
Best quarter during calendar years shown—2Q 2009: 23.56%
Worst quarter during calendar years shown—3Q 2011: (13.45)%

Year to Date Return, Label

rr_YearToDateReturnLabel

Total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

12.01%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

23.56%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(13.45%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

Indices reflect no deduction for fees, expenses or taxes, except for the MSCI All Country World Index (net) which reflects no deduction for fees and expenses.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

Average annual total returns (figures reflect sales charges) (for the periods ended December 31, 2018)

UBS Global Allocation Fund | MSCI All Country World Index (net)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(9.41%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

4.26%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

9.46%

UBS Global Allocation Fund | FTSE World Government Bond Index (Hedged in USD)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

2.60%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

3.60%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

3.25%

UBS Global Allocation Fund | 60% MSCI All Country World Index (net)/40% FTSE World Government Bond Index (Hedged in USD)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(4.53%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

4.17%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

7.24%

UBS Global Allocation Fund | CLASS A

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.50%

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Management fees

rr_ManagementFeesOverAssets

0.80%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.35%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.07%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.47%

^[2]

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

0.20%

^[3]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

1.27%

^[2],[3]

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 672

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

971

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,291

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,195

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(12.81%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

1.44%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

6.39%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 30, 1997

UBS Global Allocation Fund | CLASS P

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.80%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.33%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.07%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.20%

^[2]

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

0.18%

^[3]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

1.02%

^[2],[3]

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 104

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

363

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

642

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,439

Annual Return 2009

rr_AnnualReturn2009

35.68%

Annual Return 2010

rr_AnnualReturn2010

12.11%

Annual Return 2011

rr_AnnualReturn2011

(7.37%)

Annual Return 2012

rr_AnnualReturn2012

12.69%

Annual Return 2013

rr_AnnualReturn2013

10.53%

Annual Return 2014

rr_AnnualReturn2014

6.55%

Annual Return 2015

rr_AnnualReturn2015

(1.70%)

Annual Return 2016

rr_AnnualReturn2016

1.57%

Annual Return 2017

rr_AnnualReturn2017

17.09%

Annual Return 2018

rr_AnnualReturn2018

(7.56%)

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(7.56%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

2.86%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

7.29%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Aug. 31, 1992

UBS Global Allocation Fund | CLASS P | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(7.56%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

2.38%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

6.40%

UBS Global Allocation Fund | CLASS P | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(4.48%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

2.04%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

5.59%

[1] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[2] Since the "Acquired fund fees and expenses" are not directly borne by the Fund, they are not reflected in the Fund's financial statements, and therefore the amounts listed in "Total annual fund operating expenses" will differ from those presented in the Financial highlights.

[3] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, and extraordinary expenses to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, and extraordinary expenses), through the period ending October 28, 2020, do not exceed 1.20% for Class A shares and 0.95% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

XML

Document and Entity Information	Total
Prospectus:
Document Type	485BPOS
Document Period End Date	Jun. 30, 2019
Registrant Name	UBS FUNDS
Entity Central Index Key	0000886244
Entity Inv Company Type	N-1A
Amendment Flag	false
Document Creation Date	Oct. 28, 2019
Document Effective Date	Oct. 28, 2019
Prospectus Date	Oct. 28, 2019
UBS Dynamic Alpha Fund | CLASS P
Prospectus:
Trading Symbol	BNAYX
UBS Dynamic Alpha Fund | CLASS A
Prospectus:
Trading Symbol	BNAAX
UBS Global Allocation Fund | CLASS P
Prospectus:
Trading Symbol	BPGLX
UBS Global Allocation Fund | CLASS A
Prospectus:
Trading Symbol	BNGLX
UBS International Sustainable Equity Fund | CLASS P
Prospectus:
Trading Symbol	BNUEX
UBS International Sustainable Equity Fund | CLASS A
Prospectus:
Trading Symbol	BNIEX
UBS U.S. Small Cap Growth Fund | CLASS P
Prospectus:
Trading Symbol	BISCX
UBS U.S. Small Cap Growth Fund | CLASS A
Prospectus:
Trading Symbol	BNSCX
UBS U.S. Sustainable Equity Fund | CLASS P
Prospectus:
Trading Symbol	BPEQX
UBS U.S. Sustainable Equity Fund | Class A
Prospectus:
Trading Symbol	BNEQX
UBS Municipal Bond Fund | Class P
Prospectus:
Trading Symbol	UMBPX
UBS Municipal Bond Fund | Class A
Prospectus:
Trading Symbol	UMBAX
UBS Total Return Bond Fund | Class P
Prospectus:
Trading Symbol	UTBPX
UBS Total Return Bond Fund | Class A
Prospectus:
Trading Symbol	UTBAX
Class A & P Prospectus | UBS Emerging Markets Equity Opportunity Fund | CLASS P
Prospectus:
Trading Symbol	UEMPX
Class A & P Prospectus | UBS Emerging Markets Equity Opportunity Fund | CLASS A
Prospectus:
Trading Symbol	UEMAX
Class P2 Prospectus | UBS All China Equity Fund | Class P2
Prospectus:
Trading Symbol	ACPTX
Class P2 Prospectus | UBS Emerging Markets Equity Opportunity Fund | CLASS P2
Prospectus:
Trading Symbol	EMPTX
Class P2 Prospectus | UBS Sustainable Development Bank Bond Fund | Class P2
Prospectus:
Trading Symbol	UDBTX

XML

UBS U.S. Small Cap Growth Fund

UBS U.S. Small Cap Growth Fund

Investment objective

The Fund seeks to provide long-term capital appreciation.

Fees and expenses

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder fees (fees paid directly from your investment)

Shareholder Fees - UBS U.S. Small Cap Growth Fund	CLASS A		CLASS P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	5.50%		none
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	none	[1]	none

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - UBS U.S. Small Cap Growth Fund		CLASS A	CLASS P
Management fees		0.85%	0.85%
Distribution and/or service (12b-1) fees		0.25%	none
Other expenses		0.47%	0.45%
Acquired fund fees and expenses		0.01%	0.01%
Total annual fund operating expenses	[1]	1.58%	1.31%
Less management fee waiver/expense reimbursements	[2]	0.33%	0.31%
Total annual fund operating expenses after management fee waiver/expense reimbursements	[1],[2]	1.25%	1.00%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example - UBS U.S. Small Cap Growth Fund - USD ($)	1 year	3 years	5 years	10 years
CLASS A	670	991	1,334	2,299
CLASS P	102	385	688	1,552

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 54% of the average value of its portfolio.

Principal strategies

Principal investments

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in equity securities of US small capitalization companies. Small capitalization companies are those companies within the range of the largest and smallest company in the Russell 2000 Index at the time of purchase. However, the Fund may invest a portion of its assets in securities outside of this range. Investments in equity securities may include, but are not limited to, common stock and preferred stock; equity securities of real estate investment trusts ("REITs"); and exchange-traded funds ("ETFs"). The Fund may invest up to 20% of its net assets in foreign securities.

The Fund may, but is not required to, use exchange-traded or over-the-counter ("OTC") derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include futures and forward currency agreements. These derivatives may be used for risk management purposes to manage or adjust the risk profile of the Fund. Futures on currencies and forward currency agreements may also be used to hedge against a specific currency. In addition, futures on indices may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments; or to obtain exposure to certain markets.

Under certain market conditions, the Fund may invest in companies at the time of their initial public offering ("IPO").

Management process

In selecting securities, the Advisor seeks to invest in companies that possess dominant market positions or franchises, a major technological edge, or a unique competitive advantage. To this end, the Advisor considers earnings revision trends, positive stock price momentum and sales acceleration when selecting securities. The Fund may invest in emerging growth companies, which are companies that the Advisor expects to experience above-average earnings or cash flow growth or meaningful changes in underlying asset values.

Main risks

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments, and they may have more limited resources.

IPOs risk: The purchase of shares issued in IPOs may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time.

Focus risk: To the extent the Fund's investment strategy leads to sizable allocations to a particular market, sector or industry, the Fund may be more sensitive to any single economic, business, political, regulatory, or other event that occurs in that market, sector or industry. As a result, there may be more fluctuation in the price of the Fund's shares.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market securities. In addition, non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Performance

Risk/return bar chart and table

The performance information that follows shows the Fund's performance information in a bar chart and an average annual total returns table. The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance. An index reflects no deduction for fees, expenses or taxes. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Updated performance for the Fund is available at www.ubs.com/us-mutualfundperformance.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Total return (Class P)

Total return January 1 - September 30, 2019: 19.18%
Best quarter during calendar years shown—4Q 2010: 20.11%
Worst quarter during calendar years shown—4Q 2018: (24.27)%

Average annual total returns (figures reflect sales charges)(for the periods ended December 31, 2018)

Average Annual Returns - UBS U.S. Small Cap Growth Fund	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years	Average Annual Returns, Inception Date
CLASS A	(9.96%)	3.60%	14.06%	Dec. 31, 1998
CLASS P	(4.46%)	5.05%	15.00%	Sep. 30, 1997
After Taxes on Distributions | CLASS P	(7.34%)	1.54%	13.01%
After Taxes on Distributions and Sale of Fund Shares | CLASS P	(1.51%)	3.26%	12.32%
Russell 2000 Growth Index	(9.31%)	5.13%	13.52%

[1] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[1] Since the "Acquired fund fees and expenses" are not directly borne by the Fund, they are not reflected in the Fund's financial statements, and therefore the amounts listed in "Total annual fund operating expenses" and "Total annual fund operating expenses after management fee waiver/expense reimbursements" will differ from those presented in the Financial highlights.

[2] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc. the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, extraordinary expenses, and dividend expense and security loan fees for securities sold short) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, extraordinary expenses, and dividend expense and security loan fees for securities sold short), through the period ending October 28, 2020, do not exceed 1.24% for Class A shares and 0.99% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

XML

Label

Element

Value

UBS Dynamic Alpha Fund

Risk/Return:

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Risk/Return [Heading]

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UBS Dynamic Alpha Fund

Objective [Heading]

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Investment objective

Objective, Primary [Text Block]

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The Fund seeks to maximize total return, consisting of capital appreciation and current income.

Expense [Heading]

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Fees and expenses

Expense Narrative [Text Block]

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These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder Fees Caption [Text]

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Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Oct. 28, 2020

Portfolio Turnover [Heading]

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Portfolio turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 32% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

32.00%

Expense Breakpoint Discounts [Text]

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You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 50,000

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

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Since the "Acquired fund fees and expenses" are not directly borne by the Fund, they are not reflected in the Fund's financial statements, and therefore the amounts listed in "Total annual fund operating expenses" and "Total annual fund operating expenses after management fee waiver/expense reimbursements" will differ from those presented in the Financial highlights.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Strategy [Heading]

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Principal strategies

Strategy Narrative [Text Block]

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Principal investments

In order to achieve the Fund's objective, the Fund employs an asset allocation strategy that seeks to achieve a total rate of return for the Fund that meets or exceeds the FTSE One-Month US Treasury Bill Index plus 2%-4% (net of fees) over a rolling five year time horizon. This active management process is intended to produce superior performance relative to the benchmark (the difference of which is "alpha"). The Advisor does not represent or guarantee that the Fund will meet this total return goal.

The Fund invests in securities and financial instruments to gain exposure to global equity, global fixed income and cash equivalent markets, including global currencies. The Fund may invest in equity and fixed income securities of issuers located within and outside the United States or in open-end investment companies including those advised by the Advisor to gain exposure to certain global equity and global fixed income markets.

Investments in fixed income securities may include, but are not limited to, debt securities of governments throughout the world (including the United States), their agencies and instrumentalities, debt securities of corporations and supranationals, inflation protected securities, convertible bonds, mortgage-backed securities, asset-backed securities, equipment trusts and other collateralized debt securities. Investments in fixed income securities may include issuers in both developed (including the United States) and emerging markets. The Fund's fixed income investments may reflect a broad range of investment maturities, credit qualities and sectors, including high yield (lower-rated or "junk bonds") securities and convertible debt securities.

Investments in equity securities may include, but are not limited to, common stock and preferred stock of issuers in developed nations (including the United States) and emerging markets; and equity securities of real estate investment trusts ("REITs"). Equity investments may include securities of companies of any capitalization size.

In addition, the Fund attempts to generate positive returns and manage risk through asset allocation and sophisticated currency management techniques. These decisions are integrated with analysis of global market and economic conditions. The Fund may also take active positions on volatility to generate returns or to hedge the Fund's portfolio.

The Fund may, but is not required to, use exchange-traded or over-the-counter derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include options (including options on securities, indices, futures, forwards and swap agreements), futures, forward agreements, swap agreements (including interest rate, total return, and credit default swaps), credit-linked securities, equity participation notes and equity linked notes. All of these derivatives may be used for risk management purposes, such as hedging against a specific security or currency, or to manage or adjust the risk profile of the Fund. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments; to obtain exposure to certain markets; or to establish net short positions for individual markets, currencies or securities. Options on indices, options on swap agreements, futures on indices, forward agreements, interest rate swaps, total return swaps, credit default swaps and credit-linked securities may also be used to adjust the Fund's portfolio duration, including to achieve a negative portfolio duration.

Under certain market conditions, the Fund may invest in companies at the time of their initial public offering ("IPO"). To the extent permitted by the Investment Company Act of 1940, as amended (the "1940 Act"), the Fund may borrow money from banks to purchase investments for the Fund. The Fund may seek to implement its investment strategy through investments in exchange-traded funds ("ETFs").

Management process

The Advisor will manage the Fund's portfolio using the following investment process as described below:

The strategy invests in the full spectrum of instruments and markets globally. The Advisor believes that the Advisor is able to improve the return outcome and risk management of the Fund by employing a well diversified strategy across a broad global opportunity set. Returns are generated from asset allocation across markets, currency and security selection. The Advisor aims to employ 15-25 of the Advisor's highest conviction trade ideas into the following diversified risk buckets:

•  Market Directional: Explicit view on equities, credit, and interest rates

•  Relative Value Market: Capitalizing on misvaluation between two markets

•  Relative Value Currency: Active decisions between two markets that are made independent from market decisions

Asset allocation decisions are primarily driven by UBS AM (Americas)'s assessment of valuation and prevailing market conditions in the United States and around the world. Using a systematic approach, the portfolio management team analyzes the asset classes and investments across equities, fixed income, and alternative asset classes (including currency), considering both fundamental valuation, economic and other market indicators. Regarding valuation, the Advisor evaluates whether asset classes and investments are attractively priced relative to fundamentals. The starting point is to assess the intrinsic value of an asset class, as determined by the fundamentals that drive an asset class' future cash flow. The intrinsic value represents a long term anchor point to which the Advisor believes the asset class will eventually revert.

Fair value estimates of asset classes and markets are an output of UBS AM (Americas)'s proprietary valuation models. Discounting the asset's future cash flow using a discount rate that appropriately reflects the inherent investment risk associated with holding the asset gives the asset's fair value. The competitive advantage of the Advisor's models lies in the quality and consistency of the inputs used and, therefore, the reliability of valuation conclusions. The discrepancy between actual market level and fair value (the price/value discrepancy) is the primary valuation signal used in identifying investment opportunities.

Next, the Advisor assesses additional market indicators and considers the effect that other determinants of economic growth and overall market volatility will have on each asset class. While in theory price/value discrepancies may resolve themselves quickly and linearly, in practice price/value discrepancy can grow larger before it resolves. While valuation models have proven effective at identifying longer-term price/value discrepancies, in the shorter term other factors can swamp valuation considerations. Thus, the Advisor incorporates an additional discipline in our idea generation process. The Advisor refers to this additional step in its idea generation process as market behavior analysis. Adding this step helps the Advisor to understand what other market indicators might drive the market towards or away from fundamental value. The Advisor performs systematic analysis of non-valuation drivers using models measuring sentiment, momentum and flows, market stress, the stage of the economic cycle, as well as an assessment of the general macroeconomic landscape. Conversely, valuation considerations tend to dominate when an asset class is substantially above or below fair value, but the Advisor recognizes that the use of market behavior analysis during these periods is very important to helping improve the timing in and out of these asset classes with very stretched valuations.

The asset allocation process is structured around the Investment Solutions Investment Committee (the "ISIC Committee") meetings, which provides a forum for debate and the exploration of all ramifications of any investment decision, rather than aiming for a consensus to be reached. Instead, any voting member of the ISIC Committee can sponsor a trade idea, preparing a detailed investment thesis to support the view. An investment thesis has to define the investment rationale based on valuation and market behavioral influences, the time scale for it being realized, the transaction costs and the potential milestones the Advisor would expect to evaluate whether or not the view is correct. The sponsor is then responsible for convincing another member of the ISIC Committee to support the idea as co-sponsor.

Bottom up selection across active equity and fixed income markets can be utilized as part of the asset allocation process at the asset class level. With respect to specific equity securities for inclusion in the Fund's equity asset classes, the Advisor may utilize fundamental valuation, quantitative and growth-oriented strategies. The Advisor's bottom up fixed income security selection strategy combines judgments about the absolute value of the fixed income universe and the relative value of issuer sectors, maturity intervals, security durations, credit qualities and coupon segments, as well as specific circumstances facing the issuers of fixed income securities.

The Advisor uses both fundamental valuation and market behavior analysis to make the two-pronged determination of risk budget and risk allocation. The Advisor works closely with the Risk Management team, members of which attend the ISIC Committee meetings, to determine the appropriate amount of risk capital to allocate to the underlying trade ideas given the strategy's risk budget and objectives, prevailing investment opportunities, and other strategy exposures. To assist in this process the Risk Management team performs scenario and correlation analysis to better understand the risk and diversification of the overall strategy, and attempts to ensure that unintended factor exposures are identified, managed and monitored.

Risk [Heading]

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Main risks

Risk Narrative [Text Block]

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All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Asset allocation risk: The risk that the Fund may allocate assets to an asset category that performs poorly relative to other asset categories.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Investments in foreign government bonds involve special risks because the Fund may have limited legal recourse in the event of default. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Credit risk: The risk that the Fund could lose money if the issuer or guarantor of a fixed income security, or the counterparty to or guarantor of a derivative contract, is unable or unwilling to meet its financial obligations. This risk is likely greater for lower quality investments than for investments that are higher quality.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Interest rate risk: An increase in prevailing interest rates typically causes the value of fixed income securities to fall. Changes in interest rates will likely affect the value of longer-duration fixed income securities more than shorter-duration securities and higher quality securities more than lower quality securities. When interest rates are falling, some fixed income securities provide that the issuer may repay them earlier than the maturity date, and if this occurs the Fund may have to reinvest these repayments at lower interest rates. The Fund may face a heightened level of interest rate risk due to certain changes in monetary policy, such as certain types of interest rate changes by the Federal Reserve.

Mortgage- and asset-backed securities risk: The Fund may invest in mortgage- and asset-backed securities that are subject to prepayment or call risk, which is the risk that the borrower's payments may be received earlier or later than expected due to changes in prepayment rates on underlying loans. Faster prepayments often happen when interest rates are falling. As a result, the Fund may reinvest these early payments at lower interest rates, thereby reducing the Fund's income. Conversely, when interest rates rise, prepayments may happen more slowly, causing the security to lengthen in duration. Longer duration securities tend to be more volatile. Securities may be prepaid at a price less than the original purchase value. An unexpectedly high rate of defaults on the mortgages held by a mortgage pool may adversely affect the value of mortgage-backed securities and could result in losses to the Fund.

High yield bond risk: The risk that the issuer of bonds with ratings of Ba1 or lower by Moody's Investors Service, Inc. ("Moody's") or BB+ or lower by Standard & Poor's Financial Services LLC ("S&P") or Fitch Ratings, Inc. ("Fitch"), comparably rated by another nationally recognized statistical rating organization, or, if unrated, are determined to be of comparable quality by the Advisor will default or otherwise be unable to honor a financial obligation (also known as lower-rated or "junk bonds"). These securities are considered to be predominately speculative with respect to an issuer's capacity to pay interest and repay principal in accordance with the terms of the obligations. Lower-quality bonds are more likely to be subject to an issuer's default or downgrade than investment grade (higher quality) bonds.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments, and they may have more limited resources.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

US Government securities risk: There are different types of US government securities with different levels of credit risk, including risk of default, depending on the nature of the particular government support for that security. For example, a US government-sponsored entity, although chartered or sponsored by an Act of Congress, may issue securities that are neither insured nor guaranteed by the US Treasury and are therefore riskier than those that are.

IPOs risk: The purchase of shares issued in IPOs may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time.

Market risk: The risk that the market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with borrowing: The Fund may borrow money from banks to purchase investments for the Fund, which is a form of leverage. If the Fund borrows money to purchase securities and the Fund's investments decrease in value, the Fund's losses will be greater than if the Fund did not borrow money for investment purposes. In addition, if the return on an investment purchased with borrowed funds is not sufficient to cover the cost of borrowing, then the net income of the Fund would be less than if borrowing were not used.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market securities. Derivatives relating to fixed income markets are especially susceptible to interest rate risk and credit risk. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in other funds risk: The Fund's investment performance is affected by the investment performance of the underlying funds in which the Fund may invest. Through its investment in the underlying funds, the Fund is subject to the risks of the underlying funds' investments and subject to the underlying funds' expenses.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

Risk/return bar chart and table

The performance information that follows shows the Fund's performance information in a bar chart and an average annual total returns table. The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance. The ICE BofA Merrill Lynch 1-5 Year U.S. Treasury Index measures the performance of short-term U.S. Treasury securities. The MSCI World Index (net) shows how the Fund's performance compares to an index that is designed to measure the equity market performance of developed markets. The FTSE One-Month US Treasury Bill Index shows how the Fund's performance compares to public obligations of the US Treasury with maturities of one month. Indices reflect no deduction for fees, expenses or taxes, except for the MSCI World Index (net) which reflects no deduction for fees and expenses. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Updated performance for the Fund is available at www.ubs.com/us-mutualfundperformance.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.ubs.com/us-mutualfundperformance

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

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Total return (Class P)

Bar Chart Closing [Text Block]

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Total return January 1 - September 30, 2019: 4.66%
Best quarter during calendar years shown—2Q 2009: 18.12%
Worst quarter during calendar years shown—1Q 2009: (9.46)%

Year to Date Return, Label

rr_YearToDateReturnLabel

Total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

4.66%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

18.12%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2009

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(9.46%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

Indices reflect no deduction for fees, expenses or taxes, except for the MSCI World Index (net) which reflects no deduction for fees and expenses.

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

Average annual total returns (figures reflect sales charges) (for the periods ended December 31, 2018)

UBS Dynamic Alpha Fund | ICE BofA Merrill Lynch 1-5 Year U.S. Treasury Index

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

1.52%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

1.09%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

1.33%

UBS Dynamic Alpha Fund | MSCI World Index (net)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(8.71%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

4.56%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

9.67%

UBS Dynamic Alpha Fund | FTSE One-Month US Treasury Bill Index

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

1.82%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.57%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

0.32%

UBS Dynamic Alpha Fund | CLASS A

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.50%

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Management fees

rr_ManagementFeesOverAssets

0.85%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.92%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

Total annual fund operating expenses

rr_ExpensesOverAssets

2.05%

^[2]

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

0.67%

^[3]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

1.38%

^[2],[3]

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 683

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

1,096

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,534

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,748

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(11.34%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(2.74%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

2.96%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Jan. 27, 2005

UBS Dynamic Alpha Fund | CLASS P

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.85%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.85%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.73%

^[2]

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

0.60%

^[3]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

1.13%

^[2],[3]

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 115

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

486

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

882

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,991

Annual Return 2009

rr_AnnualReturn2009

27.33%

Annual Return 2010

rr_AnnualReturn2010

2.22%

Annual Return 2011

rr_AnnualReturn2011

(1.28%)

Annual Return 2012

rr_AnnualReturn2012

14.34%

Annual Return 2013

rr_AnnualReturn2013

6.06%

Annual Return 2014

rr_AnnualReturn2014

3.41%

Annual Return 2015

rr_AnnualReturn2015

(6.61%)

Annual Return 2016

rr_AnnualReturn2016

(1.69%)

Annual Return 2017

rr_AnnualReturn2017

4.37%

Annual Return 2018

rr_AnnualReturn2018

(5.97%)

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(5.97%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(1.40%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

3.80%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Jan. 27, 2005

UBS Dynamic Alpha Fund | CLASS P | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(6.40%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(2.14%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

3.10%

UBS Dynamic Alpha Fund | CLASS P | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(3.53%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(1.37%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

2.74%

[1] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[2] Since the "Acquired fund fees and expenses" are not directly borne by the Fund, they are not reflected in the Fund's financial statements, and therefore the amounts listed in "Total annual fund operating expenses" and "Total annual fund operating expenses after management fee waiver/expense reimbursements" will differ from those presented in the Financial highlights.

[3] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, extraordinary expenses, and dividend expense and security loan fees for securities sold short) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, extraordinary expenses, and dividend expense and security loan fees for securities sold short), through the period ending October 28, 2020, do not exceed 1.35% for Class A shares and 1.10% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

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Class P2 Prospectus | UBS Emerging Markets Equity Opportunity Fund

UBS Emerging Markets Equity Opportunity Fund

Investment objective

The Fund seeks to maximize capital appreciation.

Fees and expenses

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. Shares of Class P2 are available for purchase on behalf of clients of a fee-based program or certain other advisory programs in which UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), exercises investment discretion. Clients pay a wrap fee or a similar advisory fee to participate in such programs. Shares of Class P2 are also available for purchase on behalf of institutional clients with which the Advisor or its affiliates has signed a separate investment management agreement, pursuant to which such clients pay an advisory fee.

Shareholder fees (fees paid directly from your investment)

Shareholder Fees	Class P2 Prospectus UBS Emerging Markets Equity Opportunity Fund CLASS P2
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	none
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	none

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Class P2 Prospectus UBS Emerging Markets Equity Opportunity Fund CLASS P2
Management fees	0.90%
Distribution and/or service (12b-1) fees	none
Other expenses	0.52%
Acquired fund fees and expenses	0.02%
Total annual fund operating expenses	1.44%	[1]
Less management fee waiver/expense reimbursements	1.02%	[2]
Total annual fund operating expenses after management fee waiver/expense reimbursements	0.42%	[1],[2]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example	1 year	3 years	5 years	10 years
Class P2 Prospectus | UBS Emerging Markets Equity Opportunity Fund | CLASS P2 | USD ($)	43	355	690	1,636

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 52% of the average value of its portfolio.

Principal strategies

Principal investments

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in equity securities that are tied economically to emerging market countries. Investments in equity securities may include, but are not limited to, common stock; shares of collective trusts, investment companies, including exchange-traded funds ("ETFs"); preferred stock; securities convertible into common stock, rights, warrants and options; sponsored or unsponsored depository receipts and depository shares, including American Depositary Receipts, European Depositary Receipts and Global Depositary Receipts; equity securities of real estate investment trusts ("REITs"); securities sold in private placements; and new issues, including initial and secondary public offerings.

Securities tied economically to emerging market countries include securities on which the return is derived from issuers in emerging market countries, such as equity swap contracts and equity swap index contracts. The Fund intends to invest primarily in a portfolio of equity securities of issuers located in at least three emerging market countries, which may be located in Asia, Europe, Latin America, Africa and/or the Middle East.

The Fund may invest in stocks of companies of any size. The Fund will generally hold the stocks of between 20 to 40 issuers. The Fund may invest up to +/- 15% of its benchmark's weighting (the MSCI Emerging Markets Index) in any one country or sector.

The Fund may, but is not required to, use exchange-traded or over-the-counter derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include options (including options on securities, indices, futures, forwards, and swap agreements) futures, forward currency agreements, swap agreements (including interest rate, total return and currency) and equity participation notes and equity linked notes. All of these derivatives may be used for risk management purposes to manage or adjust the risk profile of the Fund. Futures on currencies and forward currency agreements may also be used to hedge against a specific currency. Further, the Fund may acquire and sell forward foreign currency exchange contracts in order to attempt to protect against uncertainty in the level of future foreign currency exchange rates in connection with the settlement of securities. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments (except for forward currency agreements); to obtain exposure to certain markets; or to establish net short positions for individual currencies (except for equity participation notes).

The Advisor considers a number of factors to determine whether an investment is tied to a particular country, including whether the investment is issued or guaranteed by a particular government or any of its agencies, political subdivisions, or instrumentalities; the investment has its primary trading market in a particular country; the issuer is organized under the laws of, derives at least 50% of its revenues from, or has at least 50% of its assets in a particular country; the investment is included in an index representative of a particular country or region; and the investment is exposed to the economic fortunes and risks of a particular country. The Fund considers a country's market to be an "emerging market" if it is defined as an emerging or developing economy by any of the International Bank for Reconstruction and Development (i.e., the World Bank), the International Finance Corporation or the United Nations or its authorities. Additionally, the Fund, for purposes of its investments, may consider a country included in JP Morgan or MSCI emerging markets indices to be an emerging market country. The countries included in this definition will change over time. The Fund's investments may include investments in China A-shares (shares of companies based in mainland China that trade on the Shanghai Stock Exchange and the Shenzhen Stock Exchange).

The Fund may invest in securities issued by companies in any market capitalization range, including small capitalization companies.

Management process

The Advisor employs a high alpha long opportunistic strategy, also known as the "UBS-HALO" strategy. The UBS-HALO strategy is a long-term investing approach focused on taking opportunities that seek to produce superior performance relative to the benchmark (the difference of which is "alpha"). The Advisor follows a price to intrinsic value approach. The price to intrinsic value investment philosophy means the Advisor pays great attention to investment fundamentals and expected cash flows when assessing investments.

The Advisor tries to identify and exploit periodic discrepancies between market prices and fundamental value.

These price/value discrepancies are used as the building blocks for portfolio construction.

In selecting individual securities for investment, the Advisor considers, among others:

•  A company's potential cash generation

•  Earnings outlook

•  Expected sustainable return on investments

•  Expected sustainable growth rates

•  Stock prices versus a company's asset or franchise values

Main risks

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Investments in foreign government bonds involve special risks because the Fund may have limited legal recourse in the event of default. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

Focus risk: To the extent the Fund's investment strategy leads to sizable allocations to a particular market, sector or industry, the Fund may be more sensitive to any single economic, business, political, regulatory, or other event that occurs in that market, sector or industry. As a result, there may be more fluctuation in the price of the Fund's shares.

China risk: There are special risks associated with investments in China, Hong Kong and Taiwan, including exposure to currency fluctuations, less liquidity, expropriation, confiscatory taxation, nationalization and exchange control regulations (including currency blockage). Inflation and rapid fluctuations in inflation and interest rates have had, and may continue to have, negative effects on the economy and securities markets of China, Hong Kong and Taiwan. In addition, investments in Taiwan could be adversely affected by its political and economic relationship with China. Certain securities issued by companies located or operating in China, such as China A-shares, are subject to trading restrictions, quota limitations and less market liquidity. Reduction in spending on Chinese products and services, institution of additional tariffs or other trade barriers, including as a result of heightened trade tensions between China and the United States, or a downturn in any of the economies of China's key trading partners may have an adverse impact on the Chinese economy.

Additionally, developing countries, such as China, may subject the Fund's investments to a number of tax rules, and the application of many of those rules may be uncertain. Changes in applicable Chinese tax law could reduce the after-tax profits of the Fund, directly or indirectly, including by reducing the after-tax profits of companies in China in which the Fund invests. Uncertainties in Chinese tax rules could result in unexpected tax liabilities for the Fund.

Geographic concentration risk: The risk that if the Fund has most of its investments in a single country or region, its portfolio will be more susceptible to factors adversely affecting issuers located in that country or region than would a more geographically diverse portfolio of securities.

Stock Connect investing risk: Investing in A-shares through Stock Connect is subject to trading, clearance, settlement, and other procedures, which could pose risks to the Fund. Trading through the Stock Connect program is subject to daily quotas that limit the maximum daily net purchases on any particular day, each of which may restrict or preclude the Fund's ability to invest in A-shares through the Stock Connect program. A primary feature of the Stock Connect program is the application of the home market's laws and rules applicable to investors in A-shares. Therefore, the Fund's investments in Stock Connect A-shares are generally subject to PRC securities regulations and listing rules, among other restrictions. The Shanghai and Shenzhen markets may be open at a time when the Stock Connect Program is not trading, with the result that prices of China A-shares may fluctuate at times when the Fund is unable to add to or exit its position.

China A-shares risk: China A-shares are subject to a number of restrictions imposed by Chinese securities regulations and listing rules. Investments by foreign investors in A-shares are subject to various restrictions, regulations and limits. The A-share market is volatile with a risk of suspension of trading in a particular security or multiple securities or government intervention. The A–shares market can have a higher propensity for trading suspensions than many other global equity markets. Trading suspensions could lead to greater market execution risk, valuation risks, liquidity risks, and costs for the Fund.

Furthermore, any changes in laws, regulations and policies of the China A-shares market or rules in relation to Stock Connect may affect China A-share prices. These risks are heightened by the developing state of the PRC's investment and banking systems in general.

Per a circular (Caishui [2014] 79), the Fund is expected to be temporarily exempt from the Chinese withholding tax ("WHT") on capital gains on trading in A-shares. There is no indication as to how long the temporary exemption will remain in effect. Accordingly, the Fund may be subject to such taxes in the future. If the Fund expects such WHT on trading in A-shares to be imposed, it reserves the right to establish a reserve for such tax, although it currently does not do so. If the Fund establishes such a reserve but is not ultimately subject to the tax, shareholders who redeemed or sold their shares while the reserve was in place will effectively bear the tax and may not benefit from the later release, if any, of the reserve. Conversely, if the Fund does not establish such a reserve but ultimately is subject to the tax, shareholders who redeemed or sold their shares prior to the tax being withheld, reserved or paid will have effectively avoided the tax, even if they benefited from the trading that precipitated the Fund's payment of it. Investors should note that such provision may be excessive or inadequate to meet actual WHT liabilities (which could include interest and penalties) on the Fund's investments. As a result, investors may be advantaged or disadvantaged depending on the final rules of the relevant PRC tax authorities.

Offshore RMB risk: There is no assurance that there will always be sufficient amounts of RMB (i.e., Chinese currency) available for the Fund to remain fully invested in Chinese equities. The Chinese government heavily regulates the domestic exchange of foreign currencies and RMB exchange rates in China, which may adversely affect the operations and financial results of the Fund's investments in China.

Initial public offerings ("IPOs")/private placement risk: The purchase of shares issued in IPOs and investments in the stocks of privately held companies may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time. An investment may be illiquid due to a lack of trading volume in the investment or if the investment is privately placed and not traded in any public market or is otherwise restricted from trading.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments and they may have more limited resources.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market security. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in other funds risk: The Fund's investment performance is affected by the investment performance of the underlying funds in which the Fund may invest. Through its investment in the underlying funds, the Fund is subject to the risks of the underlying funds' investments and their expenses.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Performance

There is no performance information quoted for the Fund as the Fund had not yet completed a full calendar year of operations as of the date of this prospectus.

[1] Since the "Acquired fund fees and expenses" are not directly borne by the Fund, they are not reflected in the Fund's financial statements, and therefore the amounts listed in "Total annual fund operating expenses" will differ from those presented in the Financial highlights.

[2] The Trust, with respect to the Fund, and the Advisor have entered into a written agreement pursuant to which the Advisor has agreed to waive its management fees and retained administration fees, and to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) through the period ending October 28, 2020 do not exceed 0.40%. Pursuant to the expense limitation agreement, the Advisor is entitled to be reimbursed for any expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the reimbursement or (ii) at the time of the recoupment. The expense limitation agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the expense limitation agreement, however, the Advisor's three year recoupment rights will survive.

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Label	Element	Value
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Prospectus Date	rr_ProspectusDate	Oct. 28, 2019

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Class A & P Prospectus | UBS Sustainable Development Bank Bond Fund

UBS Sustainable Development Bank Bond Fund

Investment objective

The Fund seeks current income.

Fees and expenses

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder fees (fees paid directly from your investment)

Shareholder Fees - Class A & P Prospectus - UBS Sustainable Development Bank Bond Fund	Class A		Class P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	none		none
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	none	[1]	none

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - Class A & P Prospectus - UBS Sustainable Development Bank Bond Fund		Class A	Class P
Management fees		0.15%	0.15%
Distribution and/or service (12b-1) fees		0.10%	none
Other expenses	[1]	2.04%	2.04%
Total annual fund operating expenses		2.29%	2.19%
Less management fee waiver/expense reimbursements	[2]	1.94%	1.94%
Total annual fund operating expenses after management fee waiver/expense reimbursements	[2]	0.35%	0.25%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example - Class A & P Prospectus - UBS Sustainable Development Bank Bond Fund - USD ($)	1 year	3 years	5 years	10 years
Class A	36	528	1,048	2,474
Class P	26	497	996	2,371

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. For the period October 24, 2018 (commencement of operations) through June 30, 2019, the Fund's portfolio turnover rate was 20%.

Principal strategies

Principal investments

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in bonds and/or instruments that provide exposure to bonds issued by development banks. Development banks are financial organizations formed by government entities to promote economic and social development. The Fund invests in multilateral development bank bonds but may also invest in regional or national development bank obligations. The Fund's investment in obligations issued by the International Bank for Reconstruction and Development and the Inter-American Development Bank may be significant, but the Fund normally will not invest more than 25% of its net assets in either issuer.

Under normal circumstances, the Fund will invest in securities that, at the time of purchase, possess a minimum rating of A3 by Moody's Investors Service, Inc. ("Moody's") or A- by Standard & Poor's Financial Services LLC ("S&P") or Fitch Ratings, Inc. ("Fitch"), comparably rated by another nationally recognized statistical rating organization, or, if unrated, are determined by the Advisor to be of comparable quality.

The Fund's investments in fixed income securities may have all types of interest rate payment and reset terms. The Fund generally invests only in US dollar-denominated securities.

The Fund may, but is not required to, engage in derivatives transactions. Derivatives instruments such as futures may be used for risk management purposes to hedge against a specific security or for investment (non-hedging) purposes to earn income or adjust portfolio duration. The Fund does not seek to use derivatives extensively.

The Fund may invest in exchange-traded funds ("ETFs") to gain exposure to certain asset classes.

The Fund is a non-diversified fund, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company.

Management process

The Advisor seeks to invest in bonds issued by development banks. The Advisor constructs the portfolio consisting of multilateral and regional development banks. The Advisor focuses primarily on bonds issued by multilateral development banks which may include, but are not limited to, the International Bank for Reconstruction and Development and other member institutions of the World Bank Group, the Inter-American Development Bank, the Asian Development Bank, the African Development Bank, and the European Bank for Reconstruction and Development. Development banks are formed by their member states with the objective to provide financial and technical assistance to improve overall living standards through sustainable economic development and growth. While each development bank has a distinct focus, development banks generally use their capital for projects that seek to improve the state of the developing world, promote sustainable growth and raise living standards.

The Advisor selects investments for the Fund based on available supply and liquidity parameters (including, for example, such factors as evaluating amounts outstanding, available dealer inventory, and volumes traded in the secondary market) utilizing a stratified sampling approach (investing in a representative cross-section of the investment universe) to optimize tracking error and minimize transaction cost. The Fund will be managed relative to a composite index, which is a blend of two market indexes designed to measure the performance of the US dollar denominated multilateral development bank bond market. The Fund does not seek to directly replicate the index. The Fund's composite index is the Solactive UBS Global Multilateral Development Bank Bond USD 40% 1-5 Year 60% 5-10 Year Total Return Index. (The Fund reserves the right in its discretion to change the index). The Fund's development bank bond investments may include issuers that are not part of the composite index. The Fund will seek to maintain a concentrated portfolio of development bank bonds emphasizing multilateral development banks. The portfolio management team will select the bonds in the market that meet their selection criteria with intention to provide similar risk/return characteristics as the broader development bank bond market.

The Fund may engage in active trading to adjust the portfolio in response to investor activity and to rebalance the portfolio as new development bank issuers come to the market and existing issuers enter the index or mature.

Main risks

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Risks of development bank bonds: The value of the Fund's investments in bonds issued by development banks may fall due to adverse financial market developments in the United States and abroad. Borrowers from development banks include foreign countries, which may include emerging market countries, and borrowers of specific development banks also include the private sector with or without government guarantee. Therefore, negative economic, social and political developments could affect the ability of a borrower to repay its loan to the development bank and thus affect its financial condition. In addition, investments in such development bank bonds may involve special risks because the Fund may have limited legal recourse in the event of default. Also, development bank bonds may sometimes be less liquid and more difficult to sell and to value than high-quality securities of US issuers. Bonds issued by a development bank are backed by the shareholders of the development bank. The development bank may be supported via various mechanisms, including preferred creditor status, equity injections by its shareholders and callable capital, even though the latter may have never been tested with respect to an issuer. Changes in the shareholder structure of a development bank or changes in the strength of the support by its shareholders could affect the credit rating and thus the value of the bonds issued by the development bank.

Concentration risk: The Fund concentrates in the bonds of development banks. The risk that if the Fund has most of its investments in a single industry, its portfolio will be more susceptible to factors adversely affecting that industry than would a more diverse portfolio of securities.

Interest rate risk: An increase in prevailing interest rates typically causes the value of fixed income securities to fall. Changes in interest rates will likely affect the value of longer-duration fixed income securities more than shorter-duration securities and higher quality securities more than lower quality securities. When interest rates are falling, some fixed income securities provide that the issuer may repay them earlier than the maturity date, and if this occurs the Fund may have to reinvest these repayments at lower interest rates. The Fund may face a heightened level of interest rate risk due to certain changes in monetary policy, such as certain types of interest rate changes by the Federal Reserve.

Credit risk: The risk that the Fund could lose money if the issuer or guarantor of a fixed income security, or the counterparty to or guarantor of a derivative contract, is unable or unwilling to meet its financial obligations. This risk is likely greater for lower quality investments than for investments that are higher quality.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Non-diversification risk: The Fund is a non-diversified investment company, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company. As a non-diversified fund, the Fund's share price may be more volatile, and the Fund has a greater potential to realize losses upon the occurrence of adverse events affecting a particular issuer.

Portfolio turnover risk: High portfolio turnover from frequent trading will increase the Fund's transaction costs and may increase the portion of the Fund's capital gains that are realized for tax purposes in any given year. The Fund does not restrict the frequency of trading in order to limit expenses or the tax effect that its distributions may have on shareholders.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market security. Derivatives relating to fixed income markets are especially susceptible to interest rate risk and credit risk. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Performance

There is no performance information quoted for the Fund as the Fund had not yet completed a full calendar year of operations as of the date of this prospectus.

[1] Shares of the Fund acquired through the exchange of shares of another Family Fund ("Family Funds" include PACE® Select funds, series of The UBS Funds and other funds for which UBS AM (US) serves as principal underwriter) may be subject to a deferred sales charge if you later sell the Fund shares acquired in the exchange, based on the terms of the shares of the Family Fund you originally held.

[1] "Other expenses" for Class A shares are based on estimates for the current fiscal year. "Other expenses" include "Acquired fund fees and expenses," which were less than 0.01% of the average net assets of the Fund.

[2] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses), through the period ending October 28, 2020, do not exceed 0.35% for Class A shares and 0.25% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

XML

Label

Element

Value

UBS U.S. Sustainable Equity Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

UBS U.S. Sustainable Equity Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to maximize total return, consisting of capital appreciation and current income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Oct. 28, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 102% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

102.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 50,000

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Principal investments

To achieve its investment objective, the Fund invests in, or seeks exposure to companies based on various financial factors and fundamental sustainability factors such as environmental, social and governance performance of such companies.

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in equity securities of US companies. Investments in equity securities may include, but are not limited to, dividend-paying securities; common stock; preferred stock; equity securities of real estate investment trusts ("REITs"); shares of investment companies, including exchange-traded funds ("ETFs"); convertible securities; warrants and rights.

The Fund may, but is not required to, use exchange-traded derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include futures and forward currency agreements. These derivatives may be used for risk management purposes to manage or adjust the risk profile of the Fund. Futures on currencies and forward currency agreements may also be used to hedge against a specific currency. In addition, futures on indices may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments; or to obtain exposure to certain markets.

The Fund may engage in active and frequent trading of portfolio securities to achieve its principal investment strategies.

Under certain market conditions, the Fund may invest in companies at the time of their initial public offering ("IPO").

Management process

The Advisor's investment decisions are based upon price/value discrepancies as identified by the Advisor's fundamental valuation process. In selecting securities, the Advisor focuses on, among other things, identifying discrepancies between a security's fundamental value and its market price. In this context, the fundamental value of a given security is the Advisor's assessment of what a security is worth. The Advisor will select a security whose fundamental value it estimates to be greater than its market value at any given time. For each stock under analysis, the Advisor bases its estimates of value upon economic, industry and company analysis, as well as upon a company's management team, competitive advantage and core competencies. The Advisor then compares its assessment of a security's value against the prevailing market prices, with the aim of constructing a portfolio of stocks with attractive relative price/value characteristics.

The Advisor will employ both a positive and negative screening process in selecting securities for the Fund. The positive screening process will identify securities of companies that are fundamentally attractive and that have superior valuation characteristics. In addition, the positive screening process will also include material, fundamental sustainability factors that the Advisor believes confirm the fundamental investment case and can enhance the ability to make good investment decisions. The sustainability factors are material extra-financial factors that evaluate the environmental, social and governance performance of companies that, along with more traditional financial analytics, identify companies that the Advisor believes will provide sustained, long-term value. The Advisor believes that the sustainability strategy provides the Fund with a high quality portfolio and mitigates risk.

The Advisor also applies a negative screening process that will exclude from the Fund's portfolio securities with more than 5% of sales in industries such as alcohol, tobacco, defense, nuclear, GMO (Genetically Modified Organisms), gambling and pornography. The Advisor may modify this list of negative screens at any time, without prior shareholder approval or notice.

Risk [Heading]

rr_RiskHeading

Main risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Focused investment risk: The risk that investing in a select group of securities could subject the Fund to greater risk of loss and could be considerably more volatile than the Fund's primary benchmark or other mutual funds that are diversified across a greater number of securities.

Portfolio turnover risk: High portfolio turnover from frequent trading will increase the Fund's transaction costs and may increase the portion of the Fund's capital gains that are realized for tax purposes in any given year. The Fund does not restrict the frequency of trading in order to limit expenses or the tax effect that its distributions may have on shareholders.

Sustainability factor risk: The Fund's sustainability factors used in its investment process will likely make the Fund perform differently from a fund that relies solely or primarily on financial metrics. The sustainability factors may cause the Fund's industry allocation to deviate from that of funds without these considerations.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments, and they may have more limited resources.

IPOs risk: The purchase of shares issued in IPOs may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market securities. In addition, non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

Risk/return bar chart and table

The performance information that follows shows the Fund's performance information in a bar chart and an average annual total returns table. The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance. An index reflects no deduction for fees, expenses or taxes. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. In October 2017, the Fund's investment strategies changed. The performance below for periods prior to that date is attributable to the Fund's performance before the strategy change. Updated performance for the Fund is available at www.ubs.com/us-mutualfundperformance.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.ubs.com/us-mutualfundperformance

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total return (Class P)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Total return January 1 - September 30, 2019: 22.68%
Best quarter during calendar years shown—2Q 2009: 19.55%
Worst quarter during calendar years shown—3Q 2011: (16.87)%

Year to Date Return, Label

rr_YearToDateReturnLabel

Total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

22.68%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

19.55%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(16.87%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

An index reflects no deduction for fees, expenses or taxes.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

Average annual total returns (figures reflect sales charges) (for the periods ended December 31, 2018)

UBS U.S. Sustainable Equity Fund | S&P 500 Index

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(4.38%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

8.49%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

13.12%

UBS U.S. Sustainable Equity Fund | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.50%

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Management fees

rr_ManagementFeesOverAssets

0.70%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

1.19%

^[2]

Total annual fund operating expenses

rr_ExpensesOverAssets

2.14%

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

1.19%

^[3]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

0.95%

^[3]

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 642

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

1,075

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,533

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,798

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(14.26%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

5.11%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

10.94%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 30, 1997

UBS U.S. Sustainable Equity Fund | CLASS P

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.70%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

1.15%

^[2]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.85%

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

1.15%

^[3]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

0.70%

^[3]

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 72

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

470

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

893

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,075

Annual Return 2009

rr_AnnualReturn2009

32.07%

Annual Return 2010

rr_AnnualReturn2010

13.39%

Annual Return 2011

rr_AnnualReturn2011

(2.83%)

Annual Return 2012

rr_AnnualReturn2012

13.05%

Annual Return 2013

rr_AnnualReturn2013

35.62%

Annual Return 2014

rr_AnnualReturn2014

15.13%

Annual Return 2015

rr_AnnualReturn2015

(0.83%)

Annual Return 2016

rr_AnnualReturn2016

11.12%

Annual Return 2017

rr_AnnualReturn2017

19.11%

Annual Return 2018

rr_AnnualReturn2018

(9.04%)

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(9.04%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

6.57%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

11.86%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 22, 1994

UBS U.S. Sustainable Equity Fund | CLASS P | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(9.32%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

6.29%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

11.59%

UBS U.S. Sustainable Equity Fund | CLASS P | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(5.14%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

5.13%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

9.89%

[1] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[2] "Other expenses" include "Acquired fund fees and expenses," which were less than 0.01% of the average net assets of the Fund.

[3] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses), through the period ending October 28, 2020, do not exceed 0.95% for Class A shares and 0.70% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

XML

Label

Element

Value

Class A & P Prospectus | UBS Sustainable Development Bank Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

UBS Sustainable Development Bank Bond Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks current income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Oct. 28, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. For the period October 24, 2018 (commencement of operations) through June 30, 2019, the Fund's portfolio turnover rate was 20%.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

20.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Principal investments

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in bonds and/or instruments that provide exposure to bonds issued by development banks. Development banks are financial organizations formed by government entities to promote economic and social development. The Fund invests in multilateral development bank bonds but may also invest in regional or national development bank obligations. The Fund's investment in obligations issued by the International Bank for Reconstruction and Development and the Inter-American Development Bank may be significant, but the Fund normally will not invest more than 25% of its net assets in either issuer.

Under normal circumstances, the Fund will invest in securities that, at the time of purchase, possess a minimum rating of A3 by Moody's Investors Service, Inc. ("Moody's") or A- by Standard & Poor's Financial Services LLC ("S&P") or Fitch Ratings, Inc. ("Fitch"), comparably rated by another nationally recognized statistical rating organization, or, if unrated, are determined by the Advisor to be of comparable quality.

The Fund's investments in fixed income securities may have all types of interest rate payment and reset terms. The Fund generally invests only in US dollar-denominated securities.

The Fund may, but is not required to, engage in derivatives transactions. Derivatives instruments such as futures may be used for risk management purposes to hedge against a specific security or for investment (non-hedging) purposes to earn income or adjust portfolio duration. The Fund does not seek to use derivatives extensively.

The Fund may invest in exchange-traded funds ("ETFs") to gain exposure to certain asset classes.

The Fund is a non-diversified fund, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company.

Management process

The Advisor seeks to invest in bonds issued by development banks. The Advisor constructs the portfolio consisting of multilateral and regional development banks. The Advisor focuses primarily on bonds issued by multilateral development banks which may include, but are not limited to, the International Bank for Reconstruction and Development and other member institutions of the World Bank Group, the Inter-American Development Bank, the Asian Development Bank, the African Development Bank, and the European Bank for Reconstruction and Development. Development banks are formed by their member states with the objective to provide financial and technical assistance to improve overall living standards through sustainable economic development and growth. While each development bank has a distinct focus, development banks generally use their capital for projects that seek to improve the state of the developing world, promote sustainable growth and raise living standards.

The Advisor selects investments for the Fund based on available supply and liquidity parameters (including, for example, such factors as evaluating amounts outstanding, available dealer inventory, and volumes traded in the secondary market) utilizing a stratified sampling approach (investing in a representative cross-section of the investment universe) to optimize tracking error and minimize transaction cost. The Fund will be managed relative to a composite index, which is a blend of two market indexes designed to measure the performance of the US dollar denominated multilateral development bank bond market. The Fund does not seek to directly replicate the index. The Fund's composite index is the Solactive UBS Global Multilateral Development Bank Bond USD 40% 1-5 Year 60% 5-10 Year Total Return Index. (The Fund reserves the right in its discretion to change the index). The Fund's development bank bond investments may include issuers that are not part of the composite index. The Fund will seek to maintain a concentrated portfolio of development bank bonds emphasizing multilateral development banks. The portfolio management team will select the bonds in the market that meet their selection criteria with intention to provide similar risk/return characteristics as the broader development bank bond market.

The Fund may engage in active trading to adjust the portfolio in response to investor activity and to rebalance the portfolio as new development bank issuers come to the market and existing issuers enter the index or mature.

Risk [Heading]

rr_RiskHeading

Main risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Risks of development bank bonds: The value of the Fund's investments in bonds issued by development banks may fall due to adverse financial market developments in the United States and abroad. Borrowers from development banks include foreign countries, which may include emerging market countries, and borrowers of specific development banks also include the private sector with or without government guarantee. Therefore, negative economic, social and political developments could affect the ability of a borrower to repay its loan to the development bank and thus affect its financial condition. In addition, investments in such development bank bonds may involve special risks because the Fund may have limited legal recourse in the event of default. Also, development bank bonds may sometimes be less liquid and more difficult to sell and to value than high-quality securities of US issuers. Bonds issued by a development bank are backed by the shareholders of the development bank. The development bank may be supported via various mechanisms, including preferred creditor status, equity injections by its shareholders and callable capital, even though the latter may have never been tested with respect to an issuer. Changes in the shareholder structure of a development bank or changes in the strength of the support by its shareholders could affect the credit rating and thus the value of the bonds issued by the development bank.

Concentration risk: The Fund concentrates in the bonds of development banks. The risk that if the Fund has most of its investments in a single industry, its portfolio will be more susceptible to factors adversely affecting that industry than would a more diverse portfolio of securities.

Interest rate risk: An increase in prevailing interest rates typically causes the value of fixed income securities to fall. Changes in interest rates will likely affect the value of longer-duration fixed income securities more than shorter-duration securities and higher quality securities more than lower quality securities. When interest rates are falling, some fixed income securities provide that the issuer may repay them earlier than the maturity date, and if this occurs the Fund may have to reinvest these repayments at lower interest rates. The Fund may face a heightened level of interest rate risk due to certain changes in monetary policy, such as certain types of interest rate changes by the Federal Reserve.

Credit risk: The risk that the Fund could lose money if the issuer or guarantor of a fixed income security, or the counterparty to or guarantor of a derivative contract, is unable or unwilling to meet its financial obligations. This risk is likely greater for lower quality investments than for investments that are higher quality.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Non-diversification risk: The Fund is a non-diversified investment company, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company. As a non-diversified fund, the Fund's share price may be more volatile, and the Fund has a greater potential to realize losses upon the occurrence of adverse events affecting a particular issuer.

Portfolio turnover risk: High portfolio turnover from frequent trading will increase the Fund's transaction costs and may increase the portion of the Fund's capital gains that are realized for tax purposes in any given year. The Fund does not restrict the frequency of trading in order to limit expenses or the tax effect that its distributions may have on shareholders.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market security. Derivatives relating to fixed income markets are especially susceptible to interest rate risk and credit risk. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose money by investing in the Fund.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The Fund is a non-diversified investment company, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company. As a non-diversified fund, the Fund's share price may be more volatile, and the Fund has a greater potential to realize losses upon the occurrence of adverse events affecting a particular issuer.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

There is no performance information quoted for the Fund as the Fund had not yet completed a full calendar year of operations as of the date of this prospectus.

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

There is no performance information quoted for the Fund as the Fund had not yet completed a full calendar year of operations as of the date of this prospectus.

Class A & P Prospectus | UBS Sustainable Development Bank Bond Fund | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Management fees

rr_ManagementFeesOverAssets

0.15%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.10%

Other expenses

rr_OtherExpensesOverAssets

2.04%

^[2]

Total annual fund operating expenses

rr_ExpensesOverAssets

2.29%

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

1.94%

^[3]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

0.35%

^[3]

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

"Other expenses" for Class A shares are based on estimates for the current fiscal year.

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 36

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

528

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,048

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,474

Class A & P Prospectus | UBS Sustainable Development Bank Bond Fund | Class P

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.15%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

2.04%

^[2]

Total annual fund operating expenses

rr_ExpensesOverAssets

2.19%

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

1.94%

^[3]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

0.25%

^[3]

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 26

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

497

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

996

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,371

[1] Shares of the Fund acquired through the exchange of shares of another Family Fund ("Family Funds" include PACE® Select funds, series of The UBS Funds and other funds for which UBS AM (US) serves as principal underwriter) may be subject to a deferred sales charge if you later sell the Fund shares acquired in the exchange, based on the terms of the shares of the Family Fund you originally held.

[2] "Other expenses" for Class A shares are based on estimates for the current fiscal year. "Other expenses" include "Acquired fund fees and expenses," which were less than 0.01% of the average net assets of the Fund.

[3] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses), through the period ending October 28, 2020, do not exceed 0.35% for Class A shares and 0.25% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

XML

Label

Element

Value

UBS U.S. Small Cap Growth Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

UBS U.S. Small Cap Growth Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term capital appreciation.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Oct. 28, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 54% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

54.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 50,000

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Since the "Acquired fund fees and expenses" are not directly borne by the Fund, they are not reflected in the Fund's financial statements, and therefore the amounts listed in "Total annual fund operating expenses" and "Total annual fund operating expenses after management fee waiver/expense reimbursements" will differ from those presented in the Financial highlights.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Principal investments

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in equity securities of US small capitalization companies. Small capitalization companies are those companies within the range of the largest and smallest company in the Russell 2000 Index at the time of purchase. However, the Fund may invest a portion of its assets in securities outside of this range. Investments in equity securities may include, but are not limited to, common stock and preferred stock; equity securities of real estate investment trusts ("REITs"); and exchange-traded funds ("ETFs"). The Fund may invest up to 20% of its net assets in foreign securities.

The Fund may, but is not required to, use exchange-traded or over-the-counter ("OTC") derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include futures and forward currency agreements. These derivatives may be used for risk management purposes to manage or adjust the risk profile of the Fund. Futures on currencies and forward currency agreements may also be used to hedge against a specific currency. In addition, futures on indices may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments; or to obtain exposure to certain markets.

Under certain market conditions, the Fund may invest in companies at the time of their initial public offering ("IPO").

Management process

In selecting securities, the Advisor seeks to invest in companies that possess dominant market positions or franchises, a major technological edge, or a unique competitive advantage. To this end, the Advisor considers earnings revision trends, positive stock price momentum and sales acceleration when selecting securities. The Fund may invest in emerging growth companies, which are companies that the Advisor expects to experience above-average earnings or cash flow growth or meaningful changes in underlying asset values.

Risk [Heading]

rr_RiskHeading

Main risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments, and they may have more limited resources.

IPOs risk: The purchase of shares issued in IPOs may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time.

Focus risk: To the extent the Fund's investment strategy leads to sizable allocations to a particular market, sector or industry, the Fund may be more sensitive to any single economic, business, political, regulatory, or other event that occurs in that market, sector or industry. As a result, there may be more fluctuation in the price of the Fund's shares.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market securities. In addition, non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

Risk/return bar chart and table

The performance information that follows shows the Fund's performance information in a bar chart and an average annual total returns table. The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance. An index reflects no deduction for fees, expenses or taxes. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Updated performance for the Fund is available at www.ubs.com/us-mutualfundperformance.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.ubs.com/us-mutualfundperformance

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total return (Class P)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Total return January 1 - September 30, 2019: 19.18%
Best quarter during calendar years shown—4Q 2010: 20.11%
Worst quarter during calendar years shown—4Q 2018: (24.27)%

Year to Date Return, Label

rr_YearToDateReturnLabel

Total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

19.18%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Dec. 31, 2010

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

20.11%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(24.27%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

An index reflects no deduction for fees, expenses or taxes.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

Average annual total returns (figures reflect sales charges)(for the periods ended December 31, 2018)

UBS U.S. Small Cap Growth Fund | Russell 2000 Growth Index

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(9.31%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

5.13%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

13.52%

UBS U.S. Small Cap Growth Fund | CLASS A

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.50%

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Management fees

rr_ManagementFeesOverAssets

0.85%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.47%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.58%

^[2]

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

0.33%

^[3]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

1.25%

^[2],[3]

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 670

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

991

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,334

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,299

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(9.96%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

3.60%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

14.06%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 1998

UBS U.S. Small Cap Growth Fund | CLASS P

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.85%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.45%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.31%

^[2]

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

0.31%

^[3]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

1.00%

^[2],[3]

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 102

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

385

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

688

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,552

Annual Return 2009

rr_AnnualReturn2009

33.41%

Annual Return 2010

rr_AnnualReturn2010

38.62%

Annual Return 2011

rr_AnnualReturn2011

(0.33%)

Annual Return 2012

rr_AnnualReturn2012

16.53%

Annual Return 2013

rr_AnnualReturn2013

47.29%

Annual Return 2014

rr_AnnualReturn2014

7.50%

Annual Return 2015

rr_AnnualReturn2015

(2.26%)

Annual Return 2016

rr_AnnualReturn2016

6.69%

Annual Return 2017

rr_AnnualReturn2017

19.44%

Annual Return 2018

rr_AnnualReturn2018

(4.46%)

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(4.46%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

5.05%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

15.00%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 1997

UBS U.S. Small Cap Growth Fund | CLASS P | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(7.34%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

1.54%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

13.01%

UBS U.S. Small Cap Growth Fund | CLASS P | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(1.51%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

3.26%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

12.32%

[1] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[2] Since the "Acquired fund fees and expenses" are not directly borne by the Fund, they are not reflected in the Fund's financial statements, and therefore the amounts listed in "Total annual fund operating expenses" and "Total annual fund operating expenses after management fee waiver/expense reimbursements" will differ from those presented in the Financial highlights.

[3] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc. the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, extraordinary expenses, and dividend expense and security loan fees for securities sold short) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, extraordinary expenses, and dividend expense and security loan fees for securities sold short), through the period ending October 28, 2020, do not exceed 1.24% for Class A shares and 0.99% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

XML

UBS Engage For Impact Fund

UBS Engage For Impact Fund

Investment objective

The Fund seeks to maximize total return, consisting of capital appreciation and current income.

Fees and expenses

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder fees (fees paid directly from your investment)

Shareholder Fees - UBS Engage For Impact Fund	Class A		Class P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	5.50%		none
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	none	[1]	none

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - UBS Engage For Impact Fund		Class A	Class P
Management fees		0.75%	0.75%
Distribution and/or service (12b-1) fees		0.25%	none
Other expenses	[1]	3.12%	3.12%
Total annual fund operating expenses		4.12%	3.87%
Less management fee waiver/expense reimbursements	[2]	3.02%	3.02%
Total annual fund operating expenses after management fee waiver/expense reimbursements	[2]	1.10%	0.85%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example - UBS Engage For Impact Fund - USD ($)	1 year	3 years	5 years	10 years
Class A	656	1,472	2,303	4,444
Class P	87	902	1,736	3,904

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. For the period October 24, 2018 (commencement of operations) through June 30, 2019, the Fund's portfolio turnover rate was 67%.

Principal strategies

Principal investments

To achieve its investment objective, the Fund invests in or seeks exposure to companies based on various financial factors, fundamental sustainability factors such as environmental, social and governance performance along with assessing the current and potential ability of such companies to have a measurable impact on society and the environment.

Under normal circumstances, the Fund invests a substantial portion of its net assets (plus borrowings for investment purposes, if any) in equity securities. Investments in equity securities may include, but are not limited to, dividend-paying securities, common stock and preferred stock of issuers located throughout the world; Global, European and American Depositary Receipts; equity securities of real estate investment trusts ("REITs"); as well as investment companies, including exchange-traded funds ("ETFs"). The Fund may invest in issuers from both developed markets (including the United States) and emerging markets. The Advisor, on behalf of the Fund, intends to diversify broadly among countries, but reserves the right to invest a substantial portion of the Fund's assets in one or more countries if economic and business conditions warrant such investments. The Fund may invest in stocks of companies of any size.

The Fund may, but is not required to, use exchange traded or over-the-counter ("OTC") derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include futures, forward currency agreements and equity participation notes. All of these derivatives may be used for risk management purposes to manage or adjust the risk profile of the Fund. Futures on currencies and forward currency agreements may also be used to hedge against a specific currency. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments (except for forward currency agreements); or to obtain exposure to certain markets (except for forward currency agreements). The Fund also may use futures contracts on equity securities and indices to gain market exposure on its uninvested cash.

Under certain market conditions, the Fund may invest in companies at the time of their initial public offering ("IPO").

Management process

The Advisor seeks to invest in companies that the Advisor believes are attractively valued, that integrate sustainability factors into the business model to build a competitive advantage, whose products and services can create meaningful, intentional, verifiable and measurable impact on society and the environment; and which have a clearly identified potential for additional positive impact that the Advisor intends to drive through engagement with the companies. In selecting individual securities for investment, the Advisor considers, among other factors:

•  Its assessment of fundamental valuation (price/intrinsic value) to seek attractively valued companies with strong financial performance;

•  Quantitative and qualitative environmental, social and governance ("ESG") factors;

•  Quantitative and qualitative assessment of a company's current and potential impact on society and the environment; and

•  Advisor's ability to drive positive change in a company's impact profile through engagement.

The Advisor aims to identify the best investment ideas with additional impact potential across the market capitalization spectrum, sectors and geographies within the eligible investment universe ("the impact universe").

The impact universe is comprised of companies whose products and services can create measurable, verifiable impact within specific impact categories (such as climate change, air pollution, clean water and water scarcity, treatment of disease and food security and others) that are aligned with the United Nations Sustainable Development Goals. The Advisor's assessment of the ability of public companies to generate impact is based upon impact measurement methodologies the Advisor has developed in partnership with academics from the fields of earth sciences and public health science. The impact of portfolio holdings is measured in changes in human well-being and changes in environmental quality (e.g. reduction in air pollution, hospitalizations and biodiversity loss).

Engagement with portfolio companies is a key aspect of the Fund's strategy. Companies have the potential to create additional impact through improving or optimizing the use of their products and services throughout society as well as indirectly through changes to their operations and supply chain. The Advisor's Global Sustainable Equities team and the Sustainable Research staff will seek to increase impact at each portfolio company through engagement on both fronts through communication with company management and continuous monitoring of the company's ESG impact. The Advisor will establish specific impact goals, and measure and evaluate progress regularly in order to assess the impact of its engagement efforts. The purpose of engagement with companies is to:

•  Improve the Advisor's ability to independently measure impact;

•  Engage the company to help it inform its strategy with regard to societal goals;

•  Engage the company to help increase its product and service impact by identifying target markets, customers and business partners that create additional impact over time; and

•  Engage the company to identify business model risks and opportunities linked to the ESG component of operations, supply chains and other aspects of the company that can help increase positive impact over time.

The Advisor will employ both a positive and negative screening process with regard to securities selection for the Fund. The negative screening process will exclude securities of companies with more than 5% of sales in alcohol, tobacco, defense, nuclear, gambling and pornography from the Fund's portfolio. The Advisor may modify this list of negative screens at any time, without shareholder approval or notice. The positive screening process seeks to identify securities of companies that provide solutions to significant global challenges through the impact of their products and services, that are attractive based on their fundamental and valuation profile in addition to evaluating specific sustainability (ESG) factors as well as the ability of the Advisor to engage with the company's management on impact-related issues.

Main risks

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Investments in foreign government bonds involve special risks because the Fund may have limited legal recourse in the event of default. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Sustainability factor risk and risk of impact investing: The Fund's sustainability factors used in its investment process and the Advisor's impact investing approach will likely make the Fund perform differently from a fund that relies solely or primarily on financial metrics. The sustainability factors and the Advisor's impact investing approach may cause the Fund's industry allocation to deviate from that of funds without these considerations.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments and they may have more limited resources.

Geographic concentration risk: The risk that if the Fund has most of its investments in a single country or region, its portfolio will be more susceptible to factors adversely affecting issuers located in that country or region than would a more geographically diverse portfolio of securities.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience, high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

IPOs risk: The purchase of shares issued in IPOs may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market securities. In addition, non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Performance

There is no performance information quoted for the Fund as the Fund had not yet completed a full calendar year of operations as of the date of this prospectus.

[1] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[1] "Other expenses" for Class A shares are based on estimates for the current fiscal year. "Other expenses" include "Acquired fund fees and expenses," which were less than 0.01% of the average net assets of the Fund.

[2] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses), through the period ending October 28, 2020, do not exceed 1.10% for Class A shares and 0.85% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

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UBS Dynamic Alpha Fund

UBS Dynamic Alpha Fund

Investment objective

The Fund seeks to maximize total return, consisting of capital appreciation and current income.

Fees and expenses

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder fees (fees paid directly from your investment)

Shareholder Fees - UBS Dynamic Alpha Fund	CLASS A		CLASS P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	5.50%		none
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	none	[1]	none

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - UBS Dynamic Alpha Fund		CLASS A	CLASS P
Management fees		0.85%	0.85%
Distribution and/or service (12b-1) fees		0.25%	none
Other expenses		0.92%	0.85%
Acquired fund fees and expenses		0.03%	0.03%
Total annual fund operating expenses	[1]	2.05%	1.73%
Less management fee waiver/expense reimbursements	[2]	0.67%	0.60%
Total annual fund operating expenses after management fee waiver/expense reimbursements	[1],[2]	1.38%	1.13%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example - UBS Dynamic Alpha Fund - USD ($)	1 year	3 years	5 years	10 years
CLASS A	683	1,096	1,534	2,748
CLASS P	115	486	882	1,991

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 32% of the average value of its portfolio.

Principal strategies

Principal investments

In order to achieve the Fund's objective, the Fund employs an asset allocation strategy that seeks to achieve a total rate of return for the Fund that meets or exceeds the FTSE One-Month US Treasury Bill Index plus 2%-4% (net of fees) over a rolling five year time horizon. This active management process is intended to produce superior performance relative to the benchmark (the difference of which is "alpha"). The Advisor does not represent or guarantee that the Fund will meet this total return goal.

The Fund invests in securities and financial instruments to gain exposure to global equity, global fixed income and cash equivalent markets, including global currencies. The Fund may invest in equity and fixed income securities of issuers located within and outside the United States or in open-end investment companies including those advised by the Advisor to gain exposure to certain global equity and global fixed income markets.

Investments in fixed income securities may include, but are not limited to, debt securities of governments throughout the world (including the United States), their agencies and instrumentalities, debt securities of corporations and supranationals, inflation protected securities, convertible bonds, mortgage-backed securities, asset-backed securities, equipment trusts and other collateralized debt securities. Investments in fixed income securities may include issuers in both developed (including the United States) and emerging markets. The Fund's fixed income investments may reflect a broad range of investment maturities, credit qualities and sectors, including high yield (lower-rated or "junk bonds") securities and convertible debt securities.

Investments in equity securities may include, but are not limited to, common stock and preferred stock of issuers in developed nations (including the United States) and emerging markets; and equity securities of real estate investment trusts ("REITs"). Equity investments may include securities of companies of any capitalization size.

In addition, the Fund attempts to generate positive returns and manage risk through asset allocation and sophisticated currency management techniques. These decisions are integrated with analysis of global market and economic conditions. The Fund may also take active positions on volatility to generate returns or to hedge the Fund's portfolio.

The Fund may, but is not required to, use exchange-traded or over-the-counter derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include options (including options on securities, indices, futures, forwards and swap agreements), futures, forward agreements, swap agreements (including interest rate, total return, and credit default swaps), credit-linked securities, equity participation notes and equity linked notes. All of these derivatives may be used for risk management purposes, such as hedging against a specific security or currency, or to manage or adjust the risk profile of the Fund. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments; to obtain exposure to certain markets; or to establish net short positions for individual markets, currencies or securities. Options on indices, options on swap agreements, futures on indices, forward agreements, interest rate swaps, total return swaps, credit default swaps and credit-linked securities may also be used to adjust the Fund's portfolio duration, including to achieve a negative portfolio duration.

Under certain market conditions, the Fund may invest in companies at the time of their initial public offering ("IPO"). To the extent permitted by the Investment Company Act of 1940, as amended (the "1940 Act"), the Fund may borrow money from banks to purchase investments for the Fund. The Fund may seek to implement its investment strategy through investments in exchange-traded funds ("ETFs").

Management process

The Advisor will manage the Fund's portfolio using the following investment process as described below:

The strategy invests in the full spectrum of instruments and markets globally. The Advisor believes that the Advisor is able to improve the return outcome and risk management of the Fund by employing a well diversified strategy across a broad global opportunity set. Returns are generated from asset allocation across markets, currency and security selection. The Advisor aims to employ 15-25 of the Advisor's highest conviction trade ideas into the following diversified risk buckets:

•  Market Directional: Explicit view on equities, credit, and interest rates

•  Relative Value Market: Capitalizing on misvaluation between two markets

•  Relative Value Currency: Active decisions between two markets that are made independent from market decisions

Asset allocation decisions are primarily driven by UBS AM (Americas)'s assessment of valuation and prevailing market conditions in the United States and around the world. Using a systematic approach, the portfolio management team analyzes the asset classes and investments across equities, fixed income, and alternative asset classes (including currency), considering both fundamental valuation, economic and other market indicators. Regarding valuation, the Advisor evaluates whether asset classes and investments are attractively priced relative to fundamentals. The starting point is to assess the intrinsic value of an asset class, as determined by the fundamentals that drive an asset class' future cash flow. The intrinsic value represents a long term anchor point to which the Advisor believes the asset class will eventually revert.

Fair value estimates of asset classes and markets are an output of UBS AM (Americas)'s proprietary valuation models. Discounting the asset's future cash flow using a discount rate that appropriately reflects the inherent investment risk associated with holding the asset gives the asset's fair value. The competitive advantage of the Advisor's models lies in the quality and consistency of the inputs used and, therefore, the reliability of valuation conclusions. The discrepancy between actual market level and fair value (the price/value discrepancy) is the primary valuation signal used in identifying investment opportunities.

Next, the Advisor assesses additional market indicators and considers the effect that other determinants of economic growth and overall market volatility will have on each asset class. While in theory price/value discrepancies may resolve themselves quickly and linearly, in practice price/value discrepancy can grow larger before it resolves. While valuation models have proven effective at identifying longer-term price/value discrepancies, in the shorter term other factors can swamp valuation considerations. Thus, the Advisor incorporates an additional discipline in our idea generation process. The Advisor refers to this additional step in its idea generation process as market behavior analysis. Adding this step helps the Advisor to understand what other market indicators might drive the market towards or away from fundamental value. The Advisor performs systematic analysis of non-valuation drivers using models measuring sentiment, momentum and flows, market stress, the stage of the economic cycle, as well as an assessment of the general macroeconomic landscape. Conversely, valuation considerations tend to dominate when an asset class is substantially above or below fair value, but the Advisor recognizes that the use of market behavior analysis during these periods is very important to helping improve the timing in and out of these asset classes with very stretched valuations.

The asset allocation process is structured around the Investment Solutions Investment Committee (the "ISIC Committee") meetings, which provides a forum for debate and the exploration of all ramifications of any investment decision, rather than aiming for a consensus to be reached. Instead, any voting member of the ISIC Committee can sponsor a trade idea, preparing a detailed investment thesis to support the view. An investment thesis has to define the investment rationale based on valuation and market behavioral influences, the time scale for it being realized, the transaction costs and the potential milestones the Advisor would expect to evaluate whether or not the view is correct. The sponsor is then responsible for convincing another member of the ISIC Committee to support the idea as co-sponsor.

Bottom up selection across active equity and fixed income markets can be utilized as part of the asset allocation process at the asset class level. With respect to specific equity securities for inclusion in the Fund's equity asset classes, the Advisor may utilize fundamental valuation, quantitative and growth-oriented strategies. The Advisor's bottom up fixed income security selection strategy combines judgments about the absolute value of the fixed income universe and the relative value of issuer sectors, maturity intervals, security durations, credit qualities and coupon segments, as well as specific circumstances facing the issuers of fixed income securities.

The Advisor uses both fundamental valuation and market behavior analysis to make the two-pronged determination of risk budget and risk allocation. The Advisor works closely with the Risk Management team, members of which attend the ISIC Committee meetings, to determine the appropriate amount of risk capital to allocate to the underlying trade ideas given the strategy's risk budget and objectives, prevailing investment opportunities, and other strategy exposures. To assist in this process the Risk Management team performs scenario and correlation analysis to better understand the risk and diversification of the overall strategy, and attempts to ensure that unintended factor exposures are identified, managed and monitored.

Main risks

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Asset allocation risk: The risk that the Fund may allocate assets to an asset category that performs poorly relative to other asset categories.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Investments in foreign government bonds involve special risks because the Fund may have limited legal recourse in the event of default. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Credit risk: The risk that the Fund could lose money if the issuer or guarantor of a fixed income security, or the counterparty to or guarantor of a derivative contract, is unable or unwilling to meet its financial obligations. This risk is likely greater for lower quality investments than for investments that are higher quality.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Interest rate risk: An increase in prevailing interest rates typically causes the value of fixed income securities to fall. Changes in interest rates will likely affect the value of longer-duration fixed income securities more than shorter-duration securities and higher quality securities more than lower quality securities. When interest rates are falling, some fixed income securities provide that the issuer may repay them earlier than the maturity date, and if this occurs the Fund may have to reinvest these repayments at lower interest rates. The Fund may face a heightened level of interest rate risk due to certain changes in monetary policy, such as certain types of interest rate changes by the Federal Reserve.

Mortgage- and asset-backed securities risk: The Fund may invest in mortgage- and asset-backed securities that are subject to prepayment or call risk, which is the risk that the borrower's payments may be received earlier or later than expected due to changes in prepayment rates on underlying loans. Faster prepayments often happen when interest rates are falling. As a result, the Fund may reinvest these early payments at lower interest rates, thereby reducing the Fund's income. Conversely, when interest rates rise, prepayments may happen more slowly, causing the security to lengthen in duration. Longer duration securities tend to be more volatile. Securities may be prepaid at a price less than the original purchase value. An unexpectedly high rate of defaults on the mortgages held by a mortgage pool may adversely affect the value of mortgage-backed securities and could result in losses to the Fund.

High yield bond risk: The risk that the issuer of bonds with ratings of Ba1 or lower by Moody's Investors Service, Inc. ("Moody's") or BB+ or lower by Standard & Poor's Financial Services LLC ("S&P") or Fitch Ratings, Inc. ("Fitch"), comparably rated by another nationally recognized statistical rating organization, or, if unrated, are determined to be of comparable quality by the Advisor will default or otherwise be unable to honor a financial obligation (also known as lower-rated or "junk bonds"). These securities are considered to be predominately speculative with respect to an issuer's capacity to pay interest and repay principal in accordance with the terms of the obligations. Lower-quality bonds are more likely to be subject to an issuer's default or downgrade than investment grade (higher quality) bonds.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments, and they may have more limited resources.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

US Government securities risk: There are different types of US government securities with different levels of credit risk, including risk of default, depending on the nature of the particular government support for that security. For example, a US government-sponsored entity, although chartered or sponsored by an Act of Congress, may issue securities that are neither insured nor guaranteed by the US Treasury and are therefore riskier than those that are.

IPOs risk: The purchase of shares issued in IPOs may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time.

Market risk: The risk that the market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with borrowing: The Fund may borrow money from banks to purchase investments for the Fund, which is a form of leverage. If the Fund borrows money to purchase securities and the Fund's investments decrease in value, the Fund's losses will be greater than if the Fund did not borrow money for investment purposes. In addition, if the return on an investment purchased with borrowed funds is not sufficient to cover the cost of borrowing, then the net income of the Fund would be less than if borrowing were not used.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market securities. Derivatives relating to fixed income markets are especially susceptible to interest rate risk and credit risk. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in other funds risk: The Fund's investment performance is affected by the investment performance of the underlying funds in which the Fund may invest. Through its investment in the underlying funds, the Fund is subject to the risks of the underlying funds' investments and subject to the underlying funds' expenses.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Performance

Risk/return bar chart and table

The performance information that follows shows the Fund's performance information in a bar chart and an average annual total returns table. The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance. The ICE BofA Merrill Lynch 1-5 Year U.S. Treasury Index measures the performance of short-term U.S. Treasury securities. The MSCI World Index (net) shows how the Fund's performance compares to an index that is designed to measure the equity market performance of developed markets. The FTSE One-Month US Treasury Bill Index shows how the Fund's performance compares to public obligations of the US Treasury with maturities of one month. Indices reflect no deduction for fees, expenses or taxes, except for the MSCI World Index (net) which reflects no deduction for fees and expenses. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Updated performance for the Fund is available at www.ubs.com/us-mutualfundperformance.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Total return (Class P)

Total return January 1 - September 30, 2019: 4.66%
Best quarter during calendar years shown—2Q 2009: 18.12%
Worst quarter during calendar years shown—1Q 2009: (9.46)%

Average annual total returns (figures reflect sales charges) (for the periods ended December 31, 2018)

Average Annual Returns - UBS Dynamic Alpha Fund	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years	Average Annual Returns, Inception Date
CLASS A	(11.34%)	(2.74%)	2.96%	Jan. 27, 2005
CLASS P	(5.97%)	(1.40%)	3.80%	Jan. 27, 2005
After Taxes on Distributions | CLASS P	(6.40%)	(2.14%)	3.10%
After Taxes on Distributions and Sale of Fund Shares | CLASS P	(3.53%)	(1.37%)	2.74%
ICE BofA Merrill Lynch 1-5 Year U.S. Treasury Index	1.52%	1.09%	1.33%
MSCI World Index (net)	(8.71%)	4.56%	9.67%
FTSE One-Month US Treasury Bill Index	1.82%	0.57%	0.32%

[1] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[1] Since the "Acquired fund fees and expenses" are not directly borne by the Fund, they are not reflected in the Fund's financial statements, and therefore the amounts listed in "Total annual fund operating expenses" and "Total annual fund operating expenses after management fee waiver/expense reimbursements" will differ from those presented in the Financial highlights.

[2] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, extraordinary expenses, and dividend expense and security loan fees for securities sold short) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, extraordinary expenses, and dividend expense and security loan fees for securities sold short), through the period ending October 28, 2020, do not exceed 1.35% for Class A shares and 1.10% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

XML

Label

Element

Value

Class P2 Prospectus | UBS Emerging Markets Equity Opportunity Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

UBS Emerging Markets Equity Opportunity Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to maximize capital appreciation.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. Shares of Class P2 are available for purchase on behalf of clients of a fee-based program or certain other advisory programs in which UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), exercises investment discretion. Clients pay a wrap fee or a similar advisory fee to participate in such programs. Shares of Class P2 are also available for purchase on behalf of institutional clients with which the Advisor or its affiliates has signed a separate investment management agreement, pursuant to which such clients pay an advisory fee.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Oct. 28, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 52% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

52.00%

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Since the "Acquired fund fees and expenses" are not directly borne by the Fund, they are not reflected in the Fund's financial statements, and therefore the amounts listed in "Total annual fund operating expenses" will differ from those presented in the Financial highlights.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Principal investments

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in equity securities that are tied economically to emerging market countries. Investments in equity securities may include, but are not limited to, common stock; shares of collective trusts, investment companies, including exchange-traded funds ("ETFs"); preferred stock; securities convertible into common stock, rights, warrants and options; sponsored or unsponsored depository receipts and depository shares, including American Depositary Receipts, European Depositary Receipts and Global Depositary Receipts; equity securities of real estate investment trusts ("REITs"); securities sold in private placements; and new issues, including initial and secondary public offerings.

Securities tied economically to emerging market countries include securities on which the return is derived from issuers in emerging market countries, such as equity swap contracts and equity swap index contracts. The Fund intends to invest primarily in a portfolio of equity securities of issuers located in at least three emerging market countries, which may be located in Asia, Europe, Latin America, Africa and/or the Middle East.

The Fund may invest in stocks of companies of any size. The Fund will generally hold the stocks of between 20 to 40 issuers. The Fund may invest up to +/- 15% of its benchmark's weighting (the MSCI Emerging Markets Index) in any one country or sector.

The Fund may, but is not required to, use exchange-traded or over-the-counter derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include options (including options on securities, indices, futures, forwards, and swap agreements) futures, forward currency agreements, swap agreements (including interest rate, total return and currency) and equity participation notes and equity linked notes. All of these derivatives may be used for risk management purposes to manage or adjust the risk profile of the Fund. Futures on currencies and forward currency agreements may also be used to hedge against a specific currency. Further, the Fund may acquire and sell forward foreign currency exchange contracts in order to attempt to protect against uncertainty in the level of future foreign currency exchange rates in connection with the settlement of securities. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments (except for forward currency agreements); to obtain exposure to certain markets; or to establish net short positions for individual currencies (except for equity participation notes).

The Advisor considers a number of factors to determine whether an investment is tied to a particular country, including whether the investment is issued or guaranteed by a particular government or any of its agencies, political subdivisions, or instrumentalities; the investment has its primary trading market in a particular country; the issuer is organized under the laws of, derives at least 50% of its revenues from, or has at least 50% of its assets in a particular country; the investment is included in an index representative of a particular country or region; and the investment is exposed to the economic fortunes and risks of a particular country. The Fund considers a country's market to be an "emerging market" if it is defined as an emerging or developing economy by any of the International Bank for Reconstruction and Development (i.e., the World Bank), the International Finance Corporation or the United Nations or its authorities. Additionally, the Fund, for purposes of its investments, may consider a country included in JP Morgan or MSCI emerging markets indices to be an emerging market country. The countries included in this definition will change over time. The Fund's investments may include investments in China A-shares (shares of companies based in mainland China that trade on the Shanghai Stock Exchange and the Shenzhen Stock Exchange).

The Fund may invest in securities issued by companies in any market capitalization range, including small capitalization companies.

Management process

The Advisor employs a high alpha long opportunistic strategy, also known as the "UBS-HALO" strategy. The UBS-HALO strategy is a long-term investing approach focused on taking opportunities that seek to produce superior performance relative to the benchmark (the difference of which is "alpha"). The Advisor follows a price to intrinsic value approach. The price to intrinsic value investment philosophy means the Advisor pays great attention to investment fundamentals and expected cash flows when assessing investments.

The Advisor tries to identify and exploit periodic discrepancies between market prices and fundamental value.

These price/value discrepancies are used as the building blocks for portfolio construction.

In selecting individual securities for investment, the Advisor considers, among others:

•  A company's potential cash generation

•  Earnings outlook

•  Expected sustainable return on investments

•  Expected sustainable growth rates

•  Stock prices versus a company's asset or franchise values

Risk [Heading]

rr_RiskHeading

Main risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Investments in foreign government bonds involve special risks because the Fund may have limited legal recourse in the event of default. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

Focus risk: To the extent the Fund's investment strategy leads to sizable allocations to a particular market, sector or industry, the Fund may be more sensitive to any single economic, business, political, regulatory, or other event that occurs in that market, sector or industry. As a result, there may be more fluctuation in the price of the Fund's shares.

China risk: There are special risks associated with investments in China, Hong Kong and Taiwan, including exposure to currency fluctuations, less liquidity, expropriation, confiscatory taxation, nationalization and exchange control regulations (including currency blockage). Inflation and rapid fluctuations in inflation and interest rates have had, and may continue to have, negative effects on the economy and securities markets of China, Hong Kong and Taiwan. In addition, investments in Taiwan could be adversely affected by its political and economic relationship with China. Certain securities issued by companies located or operating in China, such as China A-shares, are subject to trading restrictions, quota limitations and less market liquidity. Reduction in spending on Chinese products and services, institution of additional tariffs or other trade barriers, including as a result of heightened trade tensions between China and the United States, or a downturn in any of the economies of China's key trading partners may have an adverse impact on the Chinese economy.

Additionally, developing countries, such as China, may subject the Fund's investments to a number of tax rules, and the application of many of those rules may be uncertain. Changes in applicable Chinese tax law could reduce the after-tax profits of the Fund, directly or indirectly, including by reducing the after-tax profits of companies in China in which the Fund invests. Uncertainties in Chinese tax rules could result in unexpected tax liabilities for the Fund.

Geographic concentration risk: The risk that if the Fund has most of its investments in a single country or region, its portfolio will be more susceptible to factors adversely affecting issuers located in that country or region than would a more geographically diverse portfolio of securities.

Stock Connect investing risk: Investing in A-shares through Stock Connect is subject to trading, clearance, settlement, and other procedures, which could pose risks to the Fund. Trading through the Stock Connect program is subject to daily quotas that limit the maximum daily net purchases on any particular day, each of which may restrict or preclude the Fund's ability to invest in A-shares through the Stock Connect program. A primary feature of the Stock Connect program is the application of the home market's laws and rules applicable to investors in A-shares. Therefore, the Fund's investments in Stock Connect A-shares are generally subject to PRC securities regulations and listing rules, among other restrictions. The Shanghai and Shenzhen markets may be open at a time when the Stock Connect Program is not trading, with the result that prices of China A-shares may fluctuate at times when the Fund is unable to add to or exit its position.

China A-shares risk: China A-shares are subject to a number of restrictions imposed by Chinese securities regulations and listing rules. Investments by foreign investors in A-shares are subject to various restrictions, regulations and limits. The A-share market is volatile with a risk of suspension of trading in a particular security or multiple securities or government intervention. The A–shares market can have a higher propensity for trading suspensions than many other global equity markets. Trading suspensions could lead to greater market execution risk, valuation risks, liquidity risks, and costs for the Fund.

Furthermore, any changes in laws, regulations and policies of the China A-shares market or rules in relation to Stock Connect may affect China A-share prices. These risks are heightened by the developing state of the PRC's investment and banking systems in general.

Per a circular (Caishui [2014] 79), the Fund is expected to be temporarily exempt from the Chinese withholding tax ("WHT") on capital gains on trading in A-shares. There is no indication as to how long the temporary exemption will remain in effect. Accordingly, the Fund may be subject to such taxes in the future. If the Fund expects such WHT on trading in A-shares to be imposed, it reserves the right to establish a reserve for such tax, although it currently does not do so. If the Fund establishes such a reserve but is not ultimately subject to the tax, shareholders who redeemed or sold their shares while the reserve was in place will effectively bear the tax and may not benefit from the later release, if any, of the reserve. Conversely, if the Fund does not establish such a reserve but ultimately is subject to the tax, shareholders who redeemed or sold their shares prior to the tax being withheld, reserved or paid will have effectively avoided the tax, even if they benefited from the trading that precipitated the Fund's payment of it. Investors should note that such provision may be excessive or inadequate to meet actual WHT liabilities (which could include interest and penalties) on the Fund's investments. As a result, investors may be advantaged or disadvantaged depending on the final rules of the relevant PRC tax authorities.

Offshore RMB risk: There is no assurance that there will always be sufficient amounts of RMB (i.e., Chinese currency) available for the Fund to remain fully invested in Chinese equities. The Chinese government heavily regulates the domestic exchange of foreign currencies and RMB exchange rates in China, which may adversely affect the operations and financial results of the Fund's investments in China.

Initial public offerings ("IPOs")/private placement risk: The purchase of shares issued in IPOs and investments in the stocks of privately held companies may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time. An investment may be illiquid due to a lack of trading volume in the investment or if the investment is privately placed and not traded in any public market or is otherwise restricted from trading.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments and they may have more limited resources.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market security. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in other funds risk: The Fund's investment performance is affected by the investment performance of the underlying funds in which the Fund may invest. Through its investment in the underlying funds, the Fund is subject to the risks of the underlying funds' investments and their expenses.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

There is no performance information quoted for the Fund as the Fund had not yet completed a full calendar year of operations as of the date of this prospectus.

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

There is no performance information quoted for the Fund as the Fund had not yet completed a full calendar year of operations as of the date of this prospectus.

Class P2 Prospectus | UBS Emerging Markets Equity Opportunity Fund | CLASS P2

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.90%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.52%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.02%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.44%

^[1]

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

1.02%

^[2]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

0.42%

^[1],[2]

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 43

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

355

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

690

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,636

[1] Since the "Acquired fund fees and expenses" are not directly borne by the Fund, they are not reflected in the Fund's financial statements, and therefore the amounts listed in "Total annual fund operating expenses" will differ from those presented in the Financial highlights.

[2] The Trust, with respect to the Fund, and the Advisor have entered into a written agreement pursuant to which the Advisor has agreed to waive its management fees and retained administration fees, and to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) through the period ending October 28, 2020 do not exceed 0.40%. Pursuant to the expense limitation agreement, the Advisor is entitled to be reimbursed for any expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the reimbursement or (ii) at the time of the recoupment. The expense limitation agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the expense limitation agreement, however, the Advisor's three year recoupment rights will survive.

XML

Label

Element

Value

UBS Total Return Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

UBS Total Return Bond Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to maximize total return, consisting of capital appreciation and current income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $100,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Oct. 28, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as mark-ups, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 234% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

234.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $100,000 in the Fund.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 100,000

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Principal investments

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in bonds and/or instruments that provide exposure to bond markets.

For purposes of the Fund's 80% policy above, the Fund's investments in bonds include a variety of fixed income securities, which may include, but are not limited to, securities of the US government, its agencies and government-sponsored enterprises, securities guaranteed by the US government, corporate debt securities of US and non-US issuers, including convertible securities, obligations of non-US governments or their subdivisions, agencies and government-sponsored enterprises, obligations of international agencies or supranational entities, mortgage-backed (including commercial and residential mortgage-backed securities) and asset-backed securities, and other securitized and structured securities.

Under normal circumstances, the Fund will invest at least 75% of its net assets in securities that, at the time of purchase, are rated investment grade by an independent rating agency (or, if unrated, are deemed to be of comparable quality by the Advisor), but may invest up to 25% in securities rated below investment grade (also known as lower-rated or "junk bonds").

The Fund's investments in fixed income securities may have all types of interest rate payment and reset terms, including fixed rate, adjustable rate, zero coupon, pay-in-kind and auction rate features. In addition, the fixed income securities purchased by the Fund may be denominated in any currency, have coupons payable in any currency and may be of any maturity or duration.

The Fund invests in the United States and abroad, including emerging markets, and may purchase securities issued by domestic and foreign issuers. However, the Fund expects to limit foreign currency exposure to 25% of its net assets. Furthermore, no more than 25% of the Fund's net assets may be invested in emerging markets securities. Depending on its assessment of market conditions, the Advisor may choose to allocate the Fund's assets in any combination among these types of investments or may choose not to invest in these types of investments.

The Fund may, but is not required to, use exchange-traded or over-the-counter ("OTC") derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include options (including, options on futures, forwards and swap agreements), futures, forward agreements, swap agreements (including, interest rate, total return, currency, credit default and inflation swaps), credit-linked securities and structured investments. All of these derivatives may be used for risk management purposes, such as hedging against a specific security or currency, or to manage or adjust the risk profile of the Fund. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments; to obtain exposure to certain markets; or to establish net short positions for individual sectors, markets, currencies or securities. The Fund may use options, futures, swap agreements, credit-linked securities and structured investments to adjust the Fund's portfolio duration.

The Fund may invest in exchange-traded funds ("ETFs") to gain exposure to certain asset classes.

The Fund may engage in active and frequent trading of portfolio securities to achieve its principal investment strategies.

Management process

The Advisor's investment strategy is based on identifying compelling and attractive opportunities where the Advisor believes that the return profile sufficiently compensates for the risk of owning a position. The Advisor focuses on identifying relative value opportunities and discrepancies between observable market prices and the Advisor's own estimates of fundamental value across various maturities, sectors and issuers.

The investment process combines both a top-down and bottom-up dynamic approach to exploit diversified sources of alpha (that is, potential sources of return in excess of a base market rate). The Advisor makes active decisions related to top-down factors, including duration, yield curve, and sector positioning. After defining these parameters, portfolio managers and credit research analysts work in close collaboration to develop investment themes for industry overweights and underweights as well as to determine the portions of the credit curve that are most attractive. The team then works to select securities to build optimal portfolios using bottom-up research and analysis.

Risk [Heading]

rr_RiskHeading

Main risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Credit risk: The risk that the Fund could lose money if the issuer or guarantor of a fixed income security, or the counterparty to or guarantor of a derivative contract, is unable or unwilling to meet its financial obligations. This risk is likely greater for lower quality investments than for investments that are higher quality.

Interest rate risk: An increase in prevailing interest rates typically causes the value of fixed income securities to fall. Changes in interest rates will likely affect the value of longer-duration fixed income securities more than shorter-duration securities and higher quality securities more than lower quality securities. When interest rates are falling, some fixed income securities provide that the issuer may repay them earlier than the maturity date, and if this occurs the Fund may have to reinvest these repayments at lower interest rates. The Fund may face a heightened level of interest rate risk due to certain changes in monetary policy, such as certain types of interest rate changes by the Federal Reserve.

Mortgage- and asset-backed securities risk: The Fund may invest in mortgage- and asset-backed securities that are subject to prepayment or call risk, which is the risk that the borrower's payments may be received earlier or later than expected due to changes in prepayment rates on underlying loans. Faster prepayments often happen when interest rates are falling. As a result, the Fund may reinvest these early payments at lower interest rates, thereby reducing the Fund's income. Conversely, when interest rates rise, prepayments may happen more slowly, causing the security to lengthen in duration. Longer duration securities tend to be more volatile. Securities may be prepaid at a price less than the original purchase value. An unexpectedly high rate of defaults on the mortgages held by a mortgage pool may adversely affect the value of mortgage-backed securities and could result in losses to the Fund.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

High yield bond risk: The risk that the issuer of bonds with ratings of Ba1 or lower by Moody's Investors Service, Inc. ("Moody's") or BB+ or lower by Standard & Poor's Financial Services LLC ("S&P") or Fitch Ratings, Inc. ("Fitch"), comparably rated by another nationally recognized statistical rating organization, or, if unrated, are determined to be of comparable quality by the Advisor, will default or otherwise be unable to honor a financial obligation (also known as lower-rated or "junk bonds"). These securities are considered to be predominately speculative with respect to an issuer's capacity to pay interest and repay principal in accordance with the terms of the obligations. Lower-rated bonds are more likely to be subject to an issuer's default or downgrade than investment grade (higher quality) bonds.

US Government securities risk: There are different types of US government securities with different levels of credit risk, including the risk of default, depending on the nature of the particular government support for that security. For example, a US government-sponsored entity, although chartered or sponsored by an Act of Congress, may issue securities that are neither insured nor guaranteed by the US Treasury and are therefore riskier than those that are.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Investments in foreign government bonds involve special risks because the Fund may have limited legal recourse in the event of default. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

Portfolio turnover risk: High portfolio turnover from frequent trading will increase the Fund's transaction costs and may increase the portion of the Fund's capital gains that are realized for tax purposes in any given year. The Fund does not restrict the frequency of trading in order to limit expenses or the tax effect that its distributions may have on shareholders.

Market risk: The risk that the market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market securities. Derivatives relating to fixed income markets are especially susceptible to interest rate risk and credit risk. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

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Performance

Performance Narrative [Text Block]

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Risk/return bar chart and table

The Fund's Class P shares acquired the assets and liabilities of Fort Dearborn Income Securities, Inc., a closed-end fund (the "Predecessor Fund"), prior to the opening of business on May 23, 2016 (the "Reorganization"). The Predecessor Fund was also managed by the Advisor, and the day-to-day management of, and investment decisions for, the Fund and the Predecessor Fund are made by the same portfolio management team. The Funds have generally similar investment objectives and strategies. Therefore, the information shown below for Class P shares reflects the historical performance of the Predecessor Fund for periods prior to the Reorganization.

The performance information that follows shows the Fund's performance information in a bar chart and an average annual total returns table. The bar chart and average annual total returns table show the performance of the Predecessor Fund's performance adopted by the Class P shares of the Fund for periods prior to the Reorganization. The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance. The performance information shown for periods prior to the Reorganization is for the Predecessor Fund and may not be representative of performance of the Fund. The index reflects no deduction for fees, expenses or taxes. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Updated performance for the Fund is available at https://www.ubs.com/us-mutualfundperformance.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

https://www.ubs.com/us-mutualfundperformance

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

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Total return (Class P)

Bar Chart Closing [Text Block]

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Total return January 1 - September 30, 2019: 9.94%
Best quarter during calendar years shown—3Q 2009: 10.32%
Worst quarter during calendar years shown—2Q 2013: (4.31)%

Year to Date Return, Label

rr_YearToDateReturnLabel

Total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

9.94%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

10.32%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Jun. 30, 2013

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(4.31%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

The index reflects no deduction for fees, expenses or taxes.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

Average annual total returns(for the periods ended December 31, 2018)

UBS Total Return Bond Fund | Bloomberg Barclays US Aggregate Bond Index

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.01%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

2.52%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

3.48%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

^[1]

UBS Total Return Bond Fund | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

3.75%

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[2]

Management fees

rr_ManagementFeesOverAssets

0.50%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.93%

^[3]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.68%

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

0.93%

^[4]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

0.75%

^[4]

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 449

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

797

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,169

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,213

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(6.06%)

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

(2.11%)

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 29, 2016

UBS Total Return Bond Fund | Class P

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.50%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.95%

^[3]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.45%

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

0.95%

^[4]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

0.50%

^[4]

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 51

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

365

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

702

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,653

Annual Return 2009

rr_AnnualReturn2009

15.68%

Annual Return 2010

rr_AnnualReturn2010

10.15%

Annual Return 2011

rr_AnnualReturn2011

13.00%

Annual Return 2012

rr_AnnualReturn2012

11.62%

Annual Return 2013

rr_AnnualReturn2013

(2.21%)

Annual Return 2014

rr_AnnualReturn2014

4.69%

Annual Return 2015

rr_AnnualReturn2015

(3.04%)

Annual Return 2016

rr_AnnualReturn2016

2.68%

Annual Return 2017

rr_AnnualReturn2017

4.80%

Annual Return 2018

rr_AnnualReturn2018

(2.08%)

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(2.08%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

1.36%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

5.33%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

7.47%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 19, 1972

UBS Total Return Bond Fund | Class P | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(3.27%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(0.03%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

3.30%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

3.85%

UBS Total Return Bond Fund | Class P | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(1.23%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.42%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

3.45%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

3.90%

[1] Average annual total returns for the Bloomberg Barclays US Aggregate Bond Index for the life of each class were as follows: Class A-0.10%; Class P-N/A.

[2] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[3] "Other expenses" include "Acquired fund fees and expenses," which were less than 0.01% of the average net assets of the Fund.

[4] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses), through the period ending October 28, 2020, do not exceed 0.75% for Class A shares and 0.50% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

XML

Label

Element

Value

UBS Engage For Impact Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

UBS Engage For Impact Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to maximize total return, consisting of capital appreciation and current income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Oct. 28, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. For the period October 24, 2018 (commencement of operations) through June 30, 2019, the Fund's portfolio turnover rate was 67%.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

67.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 50,000

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Principal investments

To achieve its investment objective, the Fund invests in or seeks exposure to companies based on various financial factors, fundamental sustainability factors such as environmental, social and governance performance along with assessing the current and potential ability of such companies to have a measurable impact on society and the environment.

Under normal circumstances, the Fund invests a substantial portion of its net assets (plus borrowings for investment purposes, if any) in equity securities. Investments in equity securities may include, but are not limited to, dividend-paying securities, common stock and preferred stock of issuers located throughout the world; Global, European and American Depositary Receipts; equity securities of real estate investment trusts ("REITs"); as well as investment companies, including exchange-traded funds ("ETFs"). The Fund may invest in issuers from both developed markets (including the United States) and emerging markets. The Advisor, on behalf of the Fund, intends to diversify broadly among countries, but reserves the right to invest a substantial portion of the Fund's assets in one or more countries if economic and business conditions warrant such investments. The Fund may invest in stocks of companies of any size.

The Fund may, but is not required to, use exchange traded or over-the-counter ("OTC") derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include futures, forward currency agreements and equity participation notes. All of these derivatives may be used for risk management purposes to manage or adjust the risk profile of the Fund. Futures on currencies and forward currency agreements may also be used to hedge against a specific currency. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments (except for forward currency agreements); or to obtain exposure to certain markets (except for forward currency agreements). The Fund also may use futures contracts on equity securities and indices to gain market exposure on its uninvested cash.

Under certain market conditions, the Fund may invest in companies at the time of their initial public offering ("IPO").

Management process

The Advisor seeks to invest in companies that the Advisor believes are attractively valued, that integrate sustainability factors into the business model to build a competitive advantage, whose products and services can create meaningful, intentional, verifiable and measurable impact on society and the environment; and which have a clearly identified potential for additional positive impact that the Advisor intends to drive through engagement with the companies. In selecting individual securities for investment, the Advisor considers, among other factors:

•  Its assessment of fundamental valuation (price/intrinsic value) to seek attractively valued companies with strong financial performance;

•  Quantitative and qualitative environmental, social and governance ("ESG") factors;

•  Quantitative and qualitative assessment of a company's current and potential impact on society and the environment; and

•  Advisor's ability to drive positive change in a company's impact profile through engagement.

The Advisor aims to identify the best investment ideas with additional impact potential across the market capitalization spectrum, sectors and geographies within the eligible investment universe ("the impact universe").

The impact universe is comprised of companies whose products and services can create measurable, verifiable impact within specific impact categories (such as climate change, air pollution, clean water and water scarcity, treatment of disease and food security and others) that are aligned with the United Nations Sustainable Development Goals. The Advisor's assessment of the ability of public companies to generate impact is based upon impact measurement methodologies the Advisor has developed in partnership with academics from the fields of earth sciences and public health science. The impact of portfolio holdings is measured in changes in human well-being and changes in environmental quality (e.g. reduction in air pollution, hospitalizations and biodiversity loss).

Engagement with portfolio companies is a key aspect of the Fund's strategy. Companies have the potential to create additional impact through improving or optimizing the use of their products and services throughout society as well as indirectly through changes to their operations and supply chain. The Advisor's Global Sustainable Equities team and the Sustainable Research staff will seek to increase impact at each portfolio company through engagement on both fronts through communication with company management and continuous monitoring of the company's ESG impact. The Advisor will establish specific impact goals, and measure and evaluate progress regularly in order to assess the impact of its engagement efforts. The purpose of engagement with companies is to:

•  Improve the Advisor's ability to independently measure impact;

•  Engage the company to help it inform its strategy with regard to societal goals;

•  Engage the company to help increase its product and service impact by identifying target markets, customers and business partners that create additional impact over time; and

•  Engage the company to identify business model risks and opportunities linked to the ESG component of operations, supply chains and other aspects of the company that can help increase positive impact over time.

The Advisor will employ both a positive and negative screening process with regard to securities selection for the Fund. The negative screening process will exclude securities of companies with more than 5% of sales in alcohol, tobacco, defense, nuclear, gambling and pornography from the Fund's portfolio. The Advisor may modify this list of negative screens at any time, without shareholder approval or notice. The positive screening process seeks to identify securities of companies that provide solutions to significant global challenges through the impact of their products and services, that are attractive based on their fundamental and valuation profile in addition to evaluating specific sustainability (ESG) factors as well as the ability of the Advisor to engage with the company's management on impact-related issues.

Risk [Heading]

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Main risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Investments in foreign government bonds involve special risks because the Fund may have limited legal recourse in the event of default. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Sustainability factor risk and risk of impact investing: The Fund's sustainability factors used in its investment process and the Advisor's impact investing approach will likely make the Fund perform differently from a fund that relies solely or primarily on financial metrics. The sustainability factors and the Advisor's impact investing approach may cause the Fund's industry allocation to deviate from that of funds without these considerations.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments and they may have more limited resources.

Geographic concentration risk: The risk that if the Fund has most of its investments in a single country or region, its portfolio will be more susceptible to factors adversely affecting issuers located in that country or region than would a more geographically diverse portfolio of securities.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience, high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

IPOs risk: The purchase of shares issued in IPOs may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market securities. In addition, non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Risk Lose Money [Text]

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You may lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

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An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

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Performance

Performance Narrative [Text Block]

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There is no performance information quoted for the Fund as the Fund had not yet completed a full calendar year of operations as of the date of this prospectus.

Performance One Year or Less [Text]

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There is no performance information quoted for the Fund as the Fund had not yet completed a full calendar year of operations as of the date of this prospectus.

UBS Engage For Impact Fund | Class A

Risk/Return:

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Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.50%

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Management fees

rr_ManagementFeesOverAssets

0.75%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

3.12%

^[2]

Total annual fund operating expenses

rr_ExpensesOverAssets

4.12%

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

3.02%

^[3]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

1.10%

^[3]

Expenses Deferred Charges [Text Block]

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Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

Other Expenses, New Fund, Based on Estimates [Text]

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"Other expenses" for Class A shares are based on estimates for the current fiscal year.

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 656

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

1,472

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

2,303

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 4,444

UBS Engage For Impact Fund | Class P

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.75%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

3.12%

^[2]

Total annual fund operating expenses

rr_ExpensesOverAssets

3.87%

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

3.02%

^[3]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

0.85%

^[3]

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 87

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

902

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,736

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 3,904

[1] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[2] "Other expenses" for Class A shares are based on estimates for the current fiscal year. "Other expenses" include "Acquired fund fees and expenses," which were less than 0.01% of the average net assets of the Fund.

[3] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses), through the period ending October 28, 2020, do not exceed 1.10% for Class A shares and 0.85% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

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UBS Total Return Bond Fund

UBS Total Return Bond Fund

Investment objective

The Fund seeks to maximize total return, consisting of capital appreciation and current income.

Fees and expenses

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $100,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder fees (fees paid directly from your investment)

Shareholder Fees - UBS Total Return Bond Fund	Class A		Class P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	3.75%		none
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	none	[1]	none

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - UBS Total Return Bond Fund		Class A	Class P
Management fees		0.50%	0.50%
Distribution and/or service (12b-1) fees		0.25%	none
Other expenses	[1]	0.93%	0.95%
Total annual fund operating expenses		1.68%	1.45%
Less management fee waiver/expense reimbursements	[2]	0.93%	0.95%
Total annual fund operating expenses after management fee waiver/expense reimbursements	[2]	0.75%	0.50%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example - UBS Total Return Bond Fund - USD ($)	1 year	3 years	5 years	10 years
Class A	449	797	1,169	2,213
Class P	51	365	702	1,653

Portfolio turnover

The Fund pays transaction costs, such as mark-ups, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 234% of the average value of its portfolio.

Principal strategies

Principal investments

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in bonds and/or instruments that provide exposure to bond markets.

For purposes of the Fund's 80% policy above, the Fund's investments in bonds include a variety of fixed income securities, which may include, but are not limited to, securities of the US government, its agencies and government-sponsored enterprises, securities guaranteed by the US government, corporate debt securities of US and non-US issuers, including convertible securities, obligations of non-US governments or their subdivisions, agencies and government-sponsored enterprises, obligations of international agencies or supranational entities, mortgage-backed (including commercial and residential mortgage-backed securities) and asset-backed securities, and other securitized and structured securities.

Under normal circumstances, the Fund will invest at least 75% of its net assets in securities that, at the time of purchase, are rated investment grade by an independent rating agency (or, if unrated, are deemed to be of comparable quality by the Advisor), but may invest up to 25% in securities rated below investment grade (also known as lower-rated or "junk bonds").

The Fund's investments in fixed income securities may have all types of interest rate payment and reset terms, including fixed rate, adjustable rate, zero coupon, pay-in-kind and auction rate features. In addition, the fixed income securities purchased by the Fund may be denominated in any currency, have coupons payable in any currency and may be of any maturity or duration.

The Fund invests in the United States and abroad, including emerging markets, and may purchase securities issued by domestic and foreign issuers. However, the Fund expects to limit foreign currency exposure to 25% of its net assets. Furthermore, no more than 25% of the Fund's net assets may be invested in emerging markets securities. Depending on its assessment of market conditions, the Advisor may choose to allocate the Fund's assets in any combination among these types of investments or may choose not to invest in these types of investments.

The Fund may, but is not required to, use exchange-traded or over-the-counter ("OTC") derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include options (including, options on futures, forwards and swap agreements), futures, forward agreements, swap agreements (including, interest rate, total return, currency, credit default and inflation swaps), credit-linked securities and structured investments. All of these derivatives may be used for risk management purposes, such as hedging against a specific security or currency, or to manage or adjust the risk profile of the Fund. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments; to obtain exposure to certain markets; or to establish net short positions for individual sectors, markets, currencies or securities. The Fund may use options, futures, swap agreements, credit-linked securities and structured investments to adjust the Fund's portfolio duration.

The Fund may invest in exchange-traded funds ("ETFs") to gain exposure to certain asset classes.

The Fund may engage in active and frequent trading of portfolio securities to achieve its principal investment strategies.

Management process

The Advisor's investment strategy is based on identifying compelling and attractive opportunities where the Advisor believes that the return profile sufficiently compensates for the risk of owning a position. The Advisor focuses on identifying relative value opportunities and discrepancies between observable market prices and the Advisor's own estimates of fundamental value across various maturities, sectors and issuers.

The investment process combines both a top-down and bottom-up dynamic approach to exploit diversified sources of alpha (that is, potential sources of return in excess of a base market rate). The Advisor makes active decisions related to top-down factors, including duration, yield curve, and sector positioning. After defining these parameters, portfolio managers and credit research analysts work in close collaboration to develop investment themes for industry overweights and underweights as well as to determine the portions of the credit curve that are most attractive. The team then works to select securities to build optimal portfolios using bottom-up research and analysis.

Main risks

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Credit risk: The risk that the Fund could lose money if the issuer or guarantor of a fixed income security, or the counterparty to or guarantor of a derivative contract, is unable or unwilling to meet its financial obligations. This risk is likely greater for lower quality investments than for investments that are higher quality.

Interest rate risk: An increase in prevailing interest rates typically causes the value of fixed income securities to fall. Changes in interest rates will likely affect the value of longer-duration fixed income securities more than shorter-duration securities and higher quality securities more than lower quality securities. When interest rates are falling, some fixed income securities provide that the issuer may repay them earlier than the maturity date, and if this occurs the Fund may have to reinvest these repayments at lower interest rates. The Fund may face a heightened level of interest rate risk due to certain changes in monetary policy, such as certain types of interest rate changes by the Federal Reserve.

Mortgage- and asset-backed securities risk: The Fund may invest in mortgage- and asset-backed securities that are subject to prepayment or call risk, which is the risk that the borrower's payments may be received earlier or later than expected due to changes in prepayment rates on underlying loans. Faster prepayments often happen when interest rates are falling. As a result, the Fund may reinvest these early payments at lower interest rates, thereby reducing the Fund's income. Conversely, when interest rates rise, prepayments may happen more slowly, causing the security to lengthen in duration. Longer duration securities tend to be more volatile. Securities may be prepaid at a price less than the original purchase value. An unexpectedly high rate of defaults on the mortgages held by a mortgage pool may adversely affect the value of mortgage-backed securities and could result in losses to the Fund.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

High yield bond risk: The risk that the issuer of bonds with ratings of Ba1 or lower by Moody's Investors Service, Inc. ("Moody's") or BB+ or lower by Standard & Poor's Financial Services LLC ("S&P") or Fitch Ratings, Inc. ("Fitch"), comparably rated by another nationally recognized statistical rating organization, or, if unrated, are determined to be of comparable quality by the Advisor, will default or otherwise be unable to honor a financial obligation (also known as lower-rated or "junk bonds"). These securities are considered to be predominately speculative with respect to an issuer's capacity to pay interest and repay principal in accordance with the terms of the obligations. Lower-rated bonds are more likely to be subject to an issuer's default or downgrade than investment grade (higher quality) bonds.

US Government securities risk: There are different types of US government securities with different levels of credit risk, including the risk of default, depending on the nature of the particular government support for that security. For example, a US government-sponsored entity, although chartered or sponsored by an Act of Congress, may issue securities that are neither insured nor guaranteed by the US Treasury and are therefore riskier than those that are.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Investments in foreign government bonds involve special risks because the Fund may have limited legal recourse in the event of default. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

Portfolio turnover risk: High portfolio turnover from frequent trading will increase the Fund's transaction costs and may increase the portion of the Fund's capital gains that are realized for tax purposes in any given year. The Fund does not restrict the frequency of trading in order to limit expenses or the tax effect that its distributions may have on shareholders.

Market risk: The risk that the market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market securities. Derivatives relating to fixed income markets are especially susceptible to interest rate risk and credit risk. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Performance

Risk/return bar chart and table

The Fund's Class P shares acquired the assets and liabilities of Fort Dearborn Income Securities, Inc., a closed-end fund (the "Predecessor Fund"), prior to the opening of business on May 23, 2016 (the "Reorganization"). The Predecessor Fund was also managed by the Advisor, and the day-to-day management of, and investment decisions for, the Fund and the Predecessor Fund are made by the same portfolio management team. The Funds have generally similar investment objectives and strategies. Therefore, the information shown below for Class P shares reflects the historical performance of the Predecessor Fund for periods prior to the Reorganization.

The performance information that follows shows the Fund's performance information in a bar chart and an average annual total returns table. The bar chart and average annual total returns table show the performance of the Predecessor Fund's performance adopted by the Class P shares of the Fund for periods prior to the Reorganization. The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance. The performance information shown for periods prior to the Reorganization is for the Predecessor Fund and may not be representative of performance of the Fund. The index reflects no deduction for fees, expenses or taxes. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Updated performance for the Fund is available at https://www.ubs.com/us-mutualfundperformance.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Total return (Class P)

Total return January 1 - September 30, 2019: 9.94%
Best quarter during calendar years shown—3Q 2009: 10.32%
Worst quarter during calendar years shown—2Q 2013: (4.31)%

Average annual total returns(for the periods ended December 31, 2018)

Average Annual Returns - UBS Total Return Bond Fund	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years	Average Annual Returns, Since Inception		Average Annual Returns, Inception Date
Class A	(6.06%)			(2.11%)		Sep. 29, 2016
Class P	(2.08%)	1.36%	5.33%	7.47%		Dec. 19, 1972
After Taxes on Distributions | Class P	(3.27%)	(0.03%)	3.30%	3.85%
After Taxes on Distributions and Sale of Fund Shares | Class P	(1.23%)	0.42%	3.45%	3.90%
Bloomberg Barclays US Aggregate Bond Index	0.01%	2.52%	3.48%		[1]

[1] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[1] "Other expenses" include "Acquired fund fees and expenses," which were less than 0.01% of the average net assets of the Fund.

[2] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses), through the period ending October 28, 2020, do not exceed 0.75% for Class A shares and 0.50% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

[1] Average annual total returns for the Bloomberg Barclays US Aggregate Bond Index for the life of each class were as follows: Class A-0.10%; Class P-N/A.

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Class A & P Prospectus | UBS Emerging Markets Equity Opportunity Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

UBS Emerging Markets Equity Opportunity Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to maximize capital appreciation.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this Fund's prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Oct. 28, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 52% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

52.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 50,000

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

"Other expenses" are based on estimates for the current fiscal year.

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

The "Less management fee waiver/expense reimbursements" and "Total annual fund operating expenses after management fee waiver/expense reimbursements" are restated to reflect the Fund's current expense limitation.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Since the "Acquired fund fees and expenses" are not directly borne by the Fund, they are not reflected in the Fund's financial statements, and therefore the amounts listed in "Total annual fund operating expenses" will differ from those presented in the Financial highlights.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Principal investments

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in equity securities that are tied economically to emerging market countries. Investments in equity securities may include, but are not limited to, common stock; shares of collective trusts, investment companies, including exchange-traded funds ("ETFs"); preferred stock; securities convertible into common stock, rights, warrants and options; sponsored or unsponsored depository receipts and depository shares, including American Depositary Receipts, European Depositary Receipts and Global Depositary Receipts; equity securities of real estate investment trusts ("REITs"); securities sold in private placements; and new issues, including initial and secondary public offerings.

Securities tied economically to emerging market countries include securities on which the return is derived from issuers in emerging market countries, such as equity swap contracts and equity swap index contracts. The Fund intends to invest primarily in a portfolio of equity securities of issuers located in at least three emerging market countries, which may be located in Asia, Europe, Latin America, Africa and/or the Middle East.

The Fund may invest in stocks of companies of any size. The Fund will generally hold the stocks of between 20 to 40 issuers. The Fund may invest up to +/- 15% of its benchmark's weighting (the MSCI Emerging Markets Index) in any one country or sector.

The Fund may, but is not required to, use exchange-traded or over-the-counter derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include options (including options on securities, indices, futures, forwards, and swap agreements) futures, forward currency agreements, swap agreements (including interest rate, total return and currency) and equity participation notes and equity linked notes. All of these derivatives may be used for risk management purposes to manage or adjust the risk profile of the Fund. Futures on currencies and forward currency agreements may also be used to hedge against a specific currency. Further, the Fund may acquire and sell forward foreign currency exchange contracts in order to attempt to protect against uncertainty in the level of future foreign currency exchange rates in connection with the settlement of securities. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments (except for forward currency agreements); to obtain exposure to certain markets; or to establish net short positions for individual currencies (except for equity participation notes).

The Advisor considers a number of factors to determine whether an investment is tied to a particular country, including whether the investment is issued or guaranteed by a particular government or any of its agencies, political subdivisions, or instrumentalities; the investment has its primary trading market in a particular country; the issuer is organized under the laws of, derives at least 50% of its revenues from, or has at least 50% of its assets in a particular country; the investment is included in an index representative of a particular country or region; and the investment is exposed to the economic fortunes and risks of a particular country. The Fund considers a country's market to be an "emerging market" if it is defined as an emerging or developing economy by any of the International Bank for Reconstruction and Development (i.e., the World Bank), the International Finance Corporation or the United

Nations or its authorities. Additionally, the Fund, for purposes of its investments, may consider a country included in JP Morgan or MSCI emerging markets indices to be an emerging market country. The countries included in this definition will change over time. The Fund's investments may include investments in China A-shares (shares of companies based in mainland China that trade on the Shanghai Stock Exchange and the Shenzhen Stock Exchange).

The Fund may invest in securities issued by companies in any market capitalization range, including small capitalization companies.

Management process

The Advisor employs a high alpha long opportunistic strategy, also known as the "UBS-HALO" strategy. The UBS-HALO strategy is a long-term investing approach focused on taking opportunities that seek to produce superior performance relative to the benchmark (the difference of which is "alpha"). The Advisor follows a price to intrinsic value approach. The price to intrinsic value investment philosophy means the Advisor pays great attention to investment fundamentals and expected cash flows when assessing investments.

The Advisor tries to identify and exploit periodic discrepancies between market prices and fundamental value.

These price/value discrepancies are used as the building blocks for portfolio construction.

In selecting individual securities for investment, the Advisor considers, among others:

•  A company's potential cash generation

•  Earnings outlook

•  Expected sustainable return on investments

•  Expected sustainable growth rates

•  Stock prices versus a company's asset or franchise values

Risk [Heading]

rr_RiskHeading

Main risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Investments in foreign government bonds involve special risks because the Fund may have limited legal recourse in the event of default. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

Focus risk: To the extent the Fund's investment strategy leads to sizable allocations to a particular market, sector or industry, the Fund may be more sensitive to any single economic, business, political, regulatory, or other event that occurs in that market, sector or industry. As a result, there may be more fluctuation in the price of the Fund's shares.

China risk: There are special risks associated with investments in China, Hong Kong and Taiwan, including exposure to currency fluctuations, less liquidity, expropriation, confiscatory taxation, nationalization and exchange control regulations (including currency blockage). Inflation and rapid fluctuations in inflation and interest rates have had, and may continue to have, negative effects on the economy and securities markets of China, Hong Kong and Taiwan. In addition, investments in Taiwan could be adversely affected by its political and economic relationship with China. Certain securities issued by companies located or operating in China, such as China A-shares, are subject to trading restrictions, quota limitations and less market liquidity. Reduction in spending on Chinese products and services, institution of additional tariffs or other trade barriers, including as a result of heightened trade tensions between China and the United States, or a downturn in any of the economies of China's key trading partners may have an adverse impact on the Chinese economy.

Additionally, developing countries, such as China, may subject the Fund's investments to a number of tax rules, and the application of many of those rules may be uncertain. Changes in applicable Chinese tax law could reduce the after-tax profits of the Fund, directly or indirectly, including by reducing the after-tax profits of companies in China in which the Fund invests. Uncertainties in Chinese tax rules could result in unexpected tax liabilities for the Fund.

Geographic concentration risk: The risk that if the Fund has most of its investments in a single country or region, its portfolio will be more susceptible to factors adversely affecting issuers located in that country or region than would a more geographically diverse portfolio of securities.

Stock Connect investing risk: Investing in A-shares through Stock Connect is subject to trading, clearance, settlement, and other procedures, which could pose risks to the Fund. Trading through the Stock Connect program is subject to daily quotas that limit the maximum daily net purchases on any particular day, each of which may restrict or preclude the Fund's ability to invest in A-shares through the Stock Connect program. A primary feature of the Stock Connect program is the application of the home market's laws and rules applicable to investors in A-shares. Therefore, the Fund's investments in Stock Connect A-shares are generally subject to PRC securities regulations and listing rules, among other restrictions. The Shanghai and Shenzhen markets may be open at a time when the Stock Connect Program is not trading, with the result that prices of China A-shares may fluctuate at times when the Fund is unable to add to or exit its position.

China A-shares risk: China A-shares are subject to a number of restrictions imposed by Chinese securities regulations and listing rules. Investments by foreign investors in A-shares are subject to various restrictions, regulations and limits. The A-share market is volatile with a risk of suspension of trading in a particular security or multiple securities or government intervention. The A-shares market can have a higher propensity for trading suspensions than many other global equity markets. Trading suspensions could lead to greater market execution risk, valuation risks, liquidity risks, and costs for the Fund.

Furthermore, any changes in laws, regulations and policies of the China A-shares market or rules in relation to Stock Connect may affect China A-share prices. These risks are heightened by the developing state of the PRC's investment and banking systems in general.

Per a circular (Caishui [2014] 79), the Fund is expected to be temporarily exempt from the Chinese withholding tax ("WHT") on capital gains on trading in A-shares. There is no indication as to how long the temporary exemption will remain in effect. Accordingly, the Fund may be subject to such taxes in the future. If the Fund expects such WHT on trading in A-shares to be imposed, it reserves the right to establish a reserve for such tax, although it currently does not do so. If the Fund establishes such a reserve but is not ultimately subject to the tax, shareholders who redeemed or sold their shares while the reserve was in place will effectively bear the tax and may not benefit from the later release, if any, of the reserve. Conversely, if the Fund does not establish such a reserve but ultimately is subject to the tax, shareholders who redeemed or sold their shares prior to the tax being withheld, reserved or paid will have effectively avoided the tax, even if they benefited from the trading that precipitated the Fund's payment of it. Investors should note that such provision may be excessive or inadequate to meet actual WHT liabilities (which could include interest and penalties) on the Fund's investments. As a result, investors may be advantaged or disadvantaged depending on the final rules of the relevant PRC tax authorities.

Offshore RMB risk: There is no assurance that there will always be sufficient amounts of RMB (i.e., Chinese currency) available for the Fund to remain fully invested in Chinese equities. The Chinese government heavily regulates the domestic exchange of foreign currencies and RMB exchange rates in China, which may adversely affect the operations and financial results of the Fund's investments in China.

Initial public offerings ("IPOs")/private placement risk: The purchase of shares issued in IPOs and investments in the stocks of privately held companies may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time. An investment may be illiquid due to a lack of trading volume in the investment or if the investment is privately placed and not traded in any public market or is otherwise restricted from trading.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments, and they may have more limited resources.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market security. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in other funds risk: The Fund's investment performance is affected by the investment performance of the underlying funds in which the Fund may invest. Through its investment in the underlying funds, the Fund is subject to the risks of the underlying funds' investments and their expenses.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

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Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

There is no performance information quoted for the Fund as the Fund had not yet completed a full calendar year of operations as of the date of this prospectus.

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

There is no performance information quoted for the Fund as the Fund had not yet completed a full calendar year of operations as of the date of this prospectus.

Class A & P Prospectus | UBS Emerging Markets Equity Opportunity Fund | CLASS A

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.50%

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Management fees

rr_ManagementFeesOverAssets

0.90%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.32%

^[2]

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.02%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.49%

^[3]

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

0.22%

^[4],[5]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

1.27%

^[3],[4],[5]

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 672

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

975

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,299

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,214

Class A & P Prospectus | UBS Emerging Markets Equity Opportunity Fund | CLASS P

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.90%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.32%

^[2]

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.02%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.24%

^[3]

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

0.22%

^[4],[5]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

1.02%

^[3],[4],[5]

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 104

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

372

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

660

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,481

[1] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[2] "Other expenses" are based on estimates for the current fiscal year.

[3] Since the "Acquired fund fees and expenses" are not directly borne by the Fund, they are not reflected in the Fund's financial statements, and therefore the amounts listed in "Total annual fund operating expenses" will differ from those presented in the Financial highlights.

[4] The "Less management fee waiver/expense reimbursements" and "Total annual fund operating expenses after management fee waiver/expense reimbursements" are restated to reflect the Fund's current expense limitation.

[5] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses), through the period ending October 28, 2020, do not exceed 1.25% for Class A shares and 1.00% for Class P shares; previously, UBS Emerging Markets Equity Opportunity Fund's expense caps were 1.40% and 1.15% for Class A and P shares, respectively. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

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Class A & P Prospectus | UBS Emerging Markets Equity Opportunity Fund

UBS Emerging Markets Equity Opportunity Fund

Investment objective

The Fund seeks to maximize capital appreciation.

Fees and expenses

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this Fund's prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder fees (fees paid directly from your investment)

Shareholder Fees - Class A & P Prospectus - UBS Emerging Markets Equity Opportunity Fund	CLASS A		CLASS P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	5.50%		none
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	none	[1]	none

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - Class A & P Prospectus - UBS Emerging Markets Equity Opportunity Fund		CLASS A	CLASS P
Management fees		0.90%	0.90%
Distribution and/or service (12b-1) fees		0.25%	none
Other expenses	[1]	0.32%	0.32%
Acquired fund fees and expenses		0.02%	0.02%
Total annual fund operating expenses	[2]	1.49%	1.24%
Less management fee waiver/expense reimbursements	[3],[4]	0.22%	0.22%
Total annual fund operating expenses after management fee waiver/expense reimbursements	[2],[3],[4]	1.27%	1.02%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example - Class A & P Prospectus - UBS Emerging Markets Equity Opportunity Fund - USD ($)	1 year	3 years	5 years	10 years
CLASS A	672	975	1,299	2,214
CLASS P	104	372	660	1,481

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 52% of the average value of its portfolio.

Principal strategies

Principal investments

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in equity securities that are tied economically to emerging market countries. Investments in equity securities may include, but are not limited to, common stock; shares of collective trusts, investment companies, including exchange-traded funds ("ETFs"); preferred stock; securities convertible into common stock, rights, warrants and options; sponsored or unsponsored depository receipts and depository shares, including American Depositary Receipts, European Depositary Receipts and Global Depositary Receipts; equity securities of real estate investment trusts ("REITs"); securities sold in private placements; and new issues, including initial and secondary public offerings.

Securities tied economically to emerging market countries include securities on which the return is derived from issuers in emerging market countries, such as equity swap contracts and equity swap index contracts. The Fund intends to invest primarily in a portfolio of equity securities of issuers located in at least three emerging market countries, which may be located in Asia, Europe, Latin America, Africa and/or the Middle East.

The Fund may invest in stocks of companies of any size. The Fund will generally hold the stocks of between 20 to 40 issuers. The Fund may invest up to +/- 15% of its benchmark's weighting (the MSCI Emerging Markets Index) in any one country or sector.

The Fund may, but is not required to, use exchange-traded or over-the-counter derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include options (including options on securities, indices, futures, forwards, and swap agreements) futures, forward currency agreements, swap agreements (including interest rate, total return and currency) and equity participation notes and equity linked notes. All of these derivatives may be used for risk management purposes to manage or adjust the risk profile of the Fund. Futures on currencies and forward currency agreements may also be used to hedge against a specific currency. Further, the Fund may acquire and sell forward foreign currency exchange contracts in order to attempt to protect against uncertainty in the level of future foreign currency exchange rates in connection with the settlement of securities. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments (except for forward currency agreements); to obtain exposure to certain markets; or to establish net short positions for individual currencies (except for equity participation notes).

The Advisor considers a number of factors to determine whether an investment is tied to a particular country, including whether the investment is issued or guaranteed by a particular government or any of its agencies, political subdivisions, or instrumentalities; the investment has its primary trading market in a particular country; the issuer is organized under the laws of, derives at least 50% of its revenues from, or has at least 50% of its assets in a particular country; the investment is included in an index representative of a particular country or region; and the investment is exposed to the economic fortunes and risks of a particular country. The Fund considers a country's market to be an "emerging market" if it is defined as an emerging or developing economy by any of the International Bank for Reconstruction and Development (i.e., the World Bank), the International Finance Corporation or the United

Nations or its authorities. Additionally, the Fund, for purposes of its investments, may consider a country included in JP Morgan or MSCI emerging markets indices to be an emerging market country. The countries included in this definition will change over time. The Fund's investments may include investments in China A-shares (shares of companies based in mainland China that trade on the Shanghai Stock Exchange and the Shenzhen Stock Exchange).

The Fund may invest in securities issued by companies in any market capitalization range, including small capitalization companies.

Management process

The Advisor employs a high alpha long opportunistic strategy, also known as the "UBS-HALO" strategy. The UBS-HALO strategy is a long-term investing approach focused on taking opportunities that seek to produce superior performance relative to the benchmark (the difference of which is "alpha"). The Advisor follows a price to intrinsic value approach. The price to intrinsic value investment philosophy means the Advisor pays great attention to investment fundamentals and expected cash flows when assessing investments.

The Advisor tries to identify and exploit periodic discrepancies between market prices and fundamental value.

These price/value discrepancies are used as the building blocks for portfolio construction.

In selecting individual securities for investment, the Advisor considers, among others:

•  A company's potential cash generation

•  Earnings outlook

•  Expected sustainable return on investments

•  Expected sustainable growth rates

•  Stock prices versus a company's asset or franchise values

Main risks

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Investments in foreign government bonds involve special risks because the Fund may have limited legal recourse in the event of default. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

Focus risk: To the extent the Fund's investment strategy leads to sizable allocations to a particular market, sector or industry, the Fund may be more sensitive to any single economic, business, political, regulatory, or other event that occurs in that market, sector or industry. As a result, there may be more fluctuation in the price of the Fund's shares.

China risk: There are special risks associated with investments in China, Hong Kong and Taiwan, including exposure to currency fluctuations, less liquidity, expropriation, confiscatory taxation, nationalization and exchange control regulations (including currency blockage). Inflation and rapid fluctuations in inflation and interest rates have had, and may continue to have, negative effects on the economy and securities markets of China, Hong Kong and Taiwan. In addition, investments in Taiwan could be adversely affected by its political and economic relationship with China. Certain securities issued by companies located or operating in China, such as China A-shares, are subject to trading restrictions, quota limitations and less market liquidity. Reduction in spending on Chinese products and services, institution of additional tariffs or other trade barriers, including as a result of heightened trade tensions between China and the United States, or a downturn in any of the economies of China's key trading partners may have an adverse impact on the Chinese economy.

Additionally, developing countries, such as China, may subject the Fund's investments to a number of tax rules, and the application of many of those rules may be uncertain. Changes in applicable Chinese tax law could reduce the after-tax profits of the Fund, directly or indirectly, including by reducing the after-tax profits of companies in China in which the Fund invests. Uncertainties in Chinese tax rules could result in unexpected tax liabilities for the Fund.

Geographic concentration risk: The risk that if the Fund has most of its investments in a single country or region, its portfolio will be more susceptible to factors adversely affecting issuers located in that country or region than would a more geographically diverse portfolio of securities.

Stock Connect investing risk: Investing in A-shares through Stock Connect is subject to trading, clearance, settlement, and other procedures, which could pose risks to the Fund. Trading through the Stock Connect program is subject to daily quotas that limit the maximum daily net purchases on any particular day, each of which may restrict or preclude the Fund's ability to invest in A-shares through the Stock Connect program. A primary feature of the Stock Connect program is the application of the home market's laws and rules applicable to investors in A-shares. Therefore, the Fund's investments in Stock Connect A-shares are generally subject to PRC securities regulations and listing rules, among other restrictions. The Shanghai and Shenzhen markets may be open at a time when the Stock Connect Program is not trading, with the result that prices of China A-shares may fluctuate at times when the Fund is unable to add to or exit its position.

China A-shares risk: China A-shares are subject to a number of restrictions imposed by Chinese securities regulations and listing rules. Investments by foreign investors in A-shares are subject to various restrictions, regulations and limits. The A-share market is volatile with a risk of suspension of trading in a particular security or multiple securities or government intervention. The A-shares market can have a higher propensity for trading suspensions than many other global equity markets. Trading suspensions could lead to greater market execution risk, valuation risks, liquidity risks, and costs for the Fund.

Furthermore, any changes in laws, regulations and policies of the China A-shares market or rules in relation to Stock Connect may affect China A-share prices. These risks are heightened by the developing state of the PRC's investment and banking systems in general.

Per a circular (Caishui [2014] 79), the Fund is expected to be temporarily exempt from the Chinese withholding tax ("WHT") on capital gains on trading in A-shares. There is no indication as to how long the temporary exemption will remain in effect. Accordingly, the Fund may be subject to such taxes in the future. If the Fund expects such WHT on trading in A-shares to be imposed, it reserves the right to establish a reserve for such tax, although it currently does not do so. If the Fund establishes such a reserve but is not ultimately subject to the tax, shareholders who redeemed or sold their shares while the reserve was in place will effectively bear the tax and may not benefit from the later release, if any, of the reserve. Conversely, if the Fund does not establish such a reserve but ultimately is subject to the tax, shareholders who redeemed or sold their shares prior to the tax being withheld, reserved or paid will have effectively avoided the tax, even if they benefited from the trading that precipitated the Fund's payment of it. Investors should note that such provision may be excessive or inadequate to meet actual WHT liabilities (which could include interest and penalties) on the Fund's investments. As a result, investors may be advantaged or disadvantaged depending on the final rules of the relevant PRC tax authorities.

Offshore RMB risk: There is no assurance that there will always be sufficient amounts of RMB (i.e., Chinese currency) available for the Fund to remain fully invested in Chinese equities. The Chinese government heavily regulates the domestic exchange of foreign currencies and RMB exchange rates in China, which may adversely affect the operations and financial results of the Fund's investments in China.

Initial public offerings ("IPOs")/private placement risk: The purchase of shares issued in IPOs and investments in the stocks of privately held companies may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time. An investment may be illiquid due to a lack of trading volume in the investment or if the investment is privately placed and not traded in any public market or is otherwise restricted from trading.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments, and they may have more limited resources.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market security. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in other funds risk: The Fund's investment performance is affected by the investment performance of the underlying funds in which the Fund may invest. Through its investment in the underlying funds, the Fund is subject to the risks of the underlying funds' investments and their expenses.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Performance

There is no performance information quoted for the Fund as the Fund had not yet completed a full calendar year of operations as of the date of this prospectus.

[1] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[1] "Other expenses" are based on estimates for the current fiscal year.

[2] Since the "Acquired fund fees and expenses" are not directly borne by the Fund, they are not reflected in the Fund's financial statements, and therefore the amounts listed in "Total annual fund operating expenses" will differ from those presented in the Financial highlights.

[3] The "Less management fee waiver/expense reimbursements" and "Total annual fund operating expenses after management fee waiver/expense reimbursements" are restated to reflect the Fund's current expense limitation.

[4] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses), through the period ending October 28, 2020, do not exceed 1.25% for Class A shares and 1.00% for Class P shares; previously, UBS Emerging Markets Equity Opportunity Fund's expense caps were 1.40% and 1.15% for Class A and P shares, respectively. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

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Class A & P Prospectus | UBS All China Equity Fund

UBS All China Equity Fund

Investment objective

The Fund seeks to maximize capital appreciation.

Fees and expenses

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of the Fund's prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's Statement of Additional Information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder fees (fees paid directly from your investment)

Shareholder Fees - Class A & P Prospectus - UBS All China Equity Fund	Class A		Class P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	5.50%		none
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	none	[1]	none

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - Class A & P Prospectus - UBS All China Equity Fund		Class A	Class P
Management fees		0.85%	0.85%
Distribution and/or service (12b-1) fees		0.25%	none
Other expenses	[1]	0.60%	0.60%
Total annual fund operating expenses		1.70%	1.45%
Less management fee waiver/expense reimbursements	[2]	0.35%	0.35%
Total annual fund operating expenses after management fee waiver/expense reimbursements	[2]	1.35%	1.10%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the reduction in the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example - Class A & P Prospectus - UBS All China Equity Fund - USD ($)	1 year	3 years
Class A	680	1,024
Class P	112	424

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. Because the Fund had not yet commenced operations as of the date of this prospectus, it does not have a portfolio turnover rate to provide.

Principal strategies

Principal investments

The Advisor seeks to achieve the Fund's investment objective by investing, under normal circumstances, at least 80% of the Fund's net assets (plus borrowings for investment purposes, if any) in a portfolio of equity securities of companies economically tied to China, and in other instruments that have economic characteristics similar to such securities. For this purpose, China includes the People's Republic of China ("PRC") and Hong Kong. A security will be considered to be economically tied to China if it: (i) is issued or guaranteed by a government of China or any of its agencies, political subdivisions or instrumentalities; (ii) has its primary trading market in China; (iii) is issued by an entity organized under the laws of, derives at least 50% of its revenues from, or has at least 50% of its assets in China; (iv) is included in an index representative of China; or (v) is exposed to the economic fortunes and risks of China.

Equity securities may include common stocks; preferred stocks; equity securities of real estate investment trusts ("REITs"); shares of other investment companies, including exchange-traded funds ("ETFs"); depositary receipts; and derivative instruments related to equity securities, including equity participation notes, options and futures on individual securities and indexes. The Fund's investments may include investments in securities of companies listed on exchanges located in and outside of the PRC, including but not limited to the Hong Kong Stock Exchange, Taiwan Stock Exchange, Singapore Exchange, the New York Stock Exchange, and London Stock Exchange. The Fund's investments also include China A-shares. China A-shares are equity securities issued by companies incorporated in mainland China and are denominated and traded in renminbi ("RMB") on the Shenzhen and Shanghai Stock Exchanges through the Shanghai-Hong Kong Stock Connect program and the Shenzhen-Hong Kong Stock Connect program (collectively, "Stock Connect").

The Fund may invest in companies of any size. The Fund is a non-diversified fund, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company.

The Advisor believes that discrepancies between market price and fair value arise from market behavior and market structure, and these discrepancies provide opportunities to outperform the market. To take advantage of these opportunities, the Advisor seeks to identify upcoming industry leaders in key secular growth sectors early in the company's lifecycle and when the company's share price trades far below our estimate of the firm's fair value.

The Advisor adopts a benchmark agnostic approach (meaning that the Advisor selects companies without the benchmark by which the Fund measures performance (the MSCI All China Index) being determinative), and the Fund may have a wider deviation from the benchmark than other funds. This is expected to enable the Advisor to identify non-benchmark companies with stronger long-term growth potential than might otherwise be the case.

The Fund may, but is not required to, use exchange-traded or over-the-counter derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include options (including options on securities, indices, futures, forwards, and swap agreements), futures, forward currency agreements, swap agreements (including interest rate, total return and currency) and equity participation notes and equity linked notes. All of these derivatives may be used for risk management purposes to manage or adjust the risk profile of the Fund. Futures on currencies and forward currency agreements may also be used to hedge against a specific currency. Further, the Fund may acquire and sell forward foreign currency exchange contracts in order to attempt to protect against uncertainty in the level of future foreign currency exchange rates in connection with the settlement of securities. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments (except for forward currency agreements); to obtain exposure to certain markets; or to establish net short positions for individual currencies (except for equity participation notes).

Under certain market conditions, the Fund may invest in companies at the time of their initial public offering ("IPO").

Management process

The investment process for the All China strategy is driven by bottom-up proprietary research. As a starting point, the investment universe includes all investable quoted equities domiciled in China and/or of issuers generating the majority of their income in China. The investment team is expected to exclude companies exhibiting what we view as unsustainable business models, poor corporate governance practices, and negative industry dynamics. In order to form a qualitative assessment of a company, the Advisor scores companies based on a set of questions covering three areas:

1. Industry Structure and Company's Competitiveness

2. Trends & Profitability: Trends and Sustainability

3. Governance, disclosure, environmental and social practices

The Advisor further conducts extensive valuation analysis incorporating company/industry fundamentals, future operations, and cash generation. Peer comparisons and valuation bands are also studied based on historical and forward looking financials.

The Advisor seeks to construct a "best ideas," concentrated, high-conviction portfolio. The companies would be selected based on the attractiveness of their valuations, top down macro factors, and a conviction that the investment thesis is likely to be realized. Positions would be assigned weights based on the investment parameters for the strategy and the portfolio manager's conviction in the investment thesis. The Advisor aims to construct a portfolio diversified across many sectors with no single stock position being greater than 10% of the portfolio.

Main risks

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

China risk: There are special risks associated with investments in China, Hong Kong and Taiwan, including exposure to currency fluctuations, less liquidity, expropriation, confiscatory taxation, nationalization and exchange control regulations (including currency blockage). Inflation and rapid fluctuations in inflation and interest rates have had, and may continue to have, negative effects on the economy and securities markets of China, Hong Kong and Taiwan. In addition, investments in Taiwan could be adversely affected by its political and economic relationship with China. Certain securities issued by companies located or operating in China, such as China A-shares, are subject to trading restrictions, quota limitations and less market liquidity. Reduction in spending on Chinese products and services, institution of additional tariffs or other trade barriers, including as a result of heightened trade tensions between China and the United States, or a downturn in any of the economies of China's key trading partners may have an adverse impact on the Chinese economy.

Additionally, developing countries, such as China, may subject the Fund's investments to a number of tax rules, and the application of many of those rules may be uncertain. Changes in applicable Chinese tax law could reduce the after-tax profits of the Fund, directly or indirectly, including by reducing the after-tax profits of companies in China in which the Fund invests. Uncertainties in Chinese tax rules could result in unexpected tax liabilities for the Fund.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Investments in foreign government bonds involve special risks because the Fund may have limited legal recourse in the event of default. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

China A-shares risk: China A-shares are subject to a number of restrictions imposed by Chinese securities regulations and listing rules. Investments by foreign investors in A-shares are subject to various restrictions, regulations and limits. The A-share market is volatile with a risk of suspension of trading in a particular security or multiple securities or government intervention. The A-shares market can have a higher propensity for trading suspensions than many other global equity markets. Trading suspensions could lead to greater market execution risk, valuation risks, liquidity risks, and costs for the Fund.

Furthermore, any changes in laws, regulations and policies of the China A-shares market or rules in relation to Stock Connect may affect China A-share prices. These risks are heightened by the developing state of the PRC's investment and banking systems in general.

Per a circular (Caishui [2014] 79), the Fund is expected to be temporarily exempt from the Chinese withholding tax ("WHT") on capital gains on trading in A-shares. There is no indication as to how long the temporary exemption will remain in effect. Accordingly, the Fund may be subject to such taxes in the future. If the Fund expects such WHT on trading in A-shares to be imposed, it reserves the right to establish a reserve for such tax, although it currently does not do so. If the Fund establishes such a reserve but is not ultimately subject to the tax, shareholders who redeemed or sold their shares while the reserve was in place will effectively bear the tax and may not benefit from the later release, if any, of the reserve. Conversely, if the Fund does not establish such a reserve but ultimately is subject to the tax, shareholders who redeemed or sold their shares prior to the tax being withheld, reserved or paid will have effectively avoided the tax, even if they benefited from the trading that precipitated the Fund's payment of it. Investors should note that such provision may be excessive or inadequate to meet actual WHT liabilities (which could include interest and penalties) on the Fund's investments. As a result, investors may be advantaged or disadvantaged depending on the final rules of the relevant PRC tax authorities.

Stock Connect investing risk: Investing in A-shares through Stock Connect is subject to trading, clearance, settlement, and other procedures, which could pose risks to the Fund. Trading through the Stock Connect program is subject to daily quotas that limit the maximum daily net purchases on any particular day, each of which may restrict or preclude the Fund's ability to invest in A-shares through the Stock Connect program. A primary feature of the Stock Connect program is the application of the home market's laws and rules applicable to investors in A-shares. Therefore, the Fund's investments in Stock Connect A-shares are generally subject to PRC securities regulations and listing rules, among other restrictions. The Shanghai and Shenzhen markets may be open at a time when the Stock Connect Program is not trading, with the result that prices of China A-shares may fluctuate at times when the Fund is unable to add to or exit its position.

Offshore RMB risk: There is no assurance that there will always be sufficient amounts of RMB (i.e., Chinese currency) available for the Fund to remain fully invested in Chinese equities. The Chinese government heavily regulates the domestic exchange of foreign currencies and RMB exchange rates in China, which may adversely affect the operations and financial results of the Fund's investments in China.

Geographic concentration risk: The risk that if the Fund has most of its investments in a single country or region, its portfolio will be more susceptible to factors adversely affecting issuers located in that country or region than would a more geographically diverse portfolio of securities.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments, and they may have more limited resources.

Non-diversification risk: The Fund is a non-diversified investment company, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company. As a non-diversified fund, the Fund's share price may be more volatile, and the Fund has a greater potential to realize losses upon the occurrence of adverse events affecting a particular issuer.

IPOs risk: The purchase of shares issued in IPOs may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market security. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in other funds risk: The Fund's investment performance is affected by the investment performance of the underlying funds in which the Fund may invest. Through its investment in the underlying funds, the Fund is subject to the risks of the underlying funds' investments and their expenses.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Performance

There is no performance information quoted for the Fund as the Fund had not commenced investment operations as of the date of this prospectus.

[1] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[1] "Other expenses" are based on estimates for the current fiscal year.

[2] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, extraordinary expenses and dividend expense and security loan fees for securities sold short) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, extraordinary expenses and dividend expense and security loan fees for securities sold short), through the period ending October 28, 2020, do not exceed 1.35% for Class A shares and 1.10% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

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Class A & P Prospectus | UBS All China Equity Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

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UBS All China Equity Fund

Objective [Heading]

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Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to maximize capital appreciation.

Expense [Heading]

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Fees and expenses

Expense Narrative [Text Block]

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These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of the Fund's prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's Statement of Additional Information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder Fees Caption [Text]

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Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Oct. 28, 2020

Portfolio Turnover [Heading]

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Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. Because the Fund had not yet commenced operations as of the date of this prospectus, it does not have a portfolio turnover rate to provide.

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 50,000

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

"Other expenses" are based on estimates for the current fiscal year.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the reduction in the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Strategy [Heading]

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Principal strategies

Strategy Narrative [Text Block]

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Principal investments

The Advisor seeks to achieve the Fund's investment objective by investing, under normal circumstances, at least 80% of the Fund's net assets (plus borrowings for investment purposes, if any) in a portfolio of equity securities of companies economically tied to China, and in other instruments that have economic characteristics similar to such securities. For this purpose, China includes the People's Republic of China ("PRC") and Hong Kong. A security will be considered to be economically tied to China if it: (i) is issued or guaranteed by a government of China or any of its agencies, political subdivisions or instrumentalities; (ii) has its primary trading market in China; (iii) is issued by an entity organized under the laws of, derives at least 50% of its revenues from, or has at least 50% of its assets in China; (iv) is included in an index representative of China; or (v) is exposed to the economic fortunes and risks of China.

Equity securities may include common stocks; preferred stocks; equity securities of real estate investment trusts ("REITs"); shares of other investment companies, including exchange-traded funds ("ETFs"); depositary receipts; and derivative instruments related to equity securities, including equity participation notes, options and futures on individual securities and indexes. The Fund's investments may include investments in securities of companies listed on exchanges located in and outside of the PRC, including but not limited to the Hong Kong Stock Exchange, Taiwan Stock Exchange, Singapore Exchange, the New York Stock Exchange, and London Stock Exchange. The Fund's investments also include China A-shares. China A-shares are equity securities issued by companies incorporated in mainland China and are denominated and traded in renminbi ("RMB") on the Shenzhen and Shanghai Stock Exchanges through the Shanghai-Hong Kong Stock Connect program and the Shenzhen-Hong Kong Stock Connect program (collectively, "Stock Connect").

The Fund may invest in companies of any size. The Fund is a non-diversified fund, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company.

The Advisor believes that discrepancies between market price and fair value arise from market behavior and market structure, and these discrepancies provide opportunities to outperform the market. To take advantage of these opportunities, the Advisor seeks to identify upcoming industry leaders in key secular growth sectors early in the company's lifecycle and when the company's share price trades far below our estimate of the firm's fair value.

The Advisor adopts a benchmark agnostic approach (meaning that the Advisor selects companies without the benchmark by which the Fund measures performance (the MSCI All China Index) being determinative), and the Fund may have a wider deviation from the benchmark than other funds. This is expected to enable the Advisor to identify non-benchmark companies with stronger long-term growth potential than might otherwise be the case.

The Fund may, but is not required to, use exchange-traded or over-the-counter derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include options (including options on securities, indices, futures, forwards, and swap agreements), futures, forward currency agreements, swap agreements (including interest rate, total return and currency) and equity participation notes and equity linked notes. All of these derivatives may be used for risk management purposes to manage or adjust the risk profile of the Fund. Futures on currencies and forward currency agreements may also be used to hedge against a specific currency. Further, the Fund may acquire and sell forward foreign currency exchange contracts in order to attempt to protect against uncertainty in the level of future foreign currency exchange rates in connection with the settlement of securities. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments (except for forward currency agreements); to obtain exposure to certain markets; or to establish net short positions for individual currencies (except for equity participation notes).

Under certain market conditions, the Fund may invest in companies at the time of their initial public offering ("IPO").

Management process

The investment process for the All China strategy is driven by bottom-up proprietary research. As a starting point, the investment universe includes all investable quoted equities domiciled in China and/or of issuers generating the majority of their income in China. The investment team is expected to exclude companies exhibiting what we view as unsustainable business models, poor corporate governance practices, and negative industry dynamics. In order to form a qualitative assessment of a company, the Advisor scores companies based on a set of questions covering three areas:

1. Industry Structure and Company's Competitiveness

2. Trends & Profitability: Trends and Sustainability

3. Governance, disclosure, environmental and social practices

The Advisor further conducts extensive valuation analysis incorporating company/industry fundamentals, future operations, and cash generation. Peer comparisons and valuation bands are also studied based on historical and forward looking financials.

The Advisor seeks to construct a "best ideas," concentrated, high-conviction portfolio. The companies would be selected based on the attractiveness of their valuations, top down macro factors, and a conviction that the investment thesis is likely to be realized. Positions would be assigned weights based on the investment parameters for the strategy and the portfolio manager's conviction in the investment thesis. The Advisor aims to construct a portfolio diversified across many sectors with no single stock position being greater than 10% of the portfolio.

Risk [Heading]

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Main risks

Risk Narrative [Text Block]

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All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

China risk: There are special risks associated with investments in China, Hong Kong and Taiwan, including exposure to currency fluctuations, less liquidity, expropriation, confiscatory taxation, nationalization and exchange control regulations (including currency blockage). Inflation and rapid fluctuations in inflation and interest rates have had, and may continue to have, negative effects on the economy and securities markets of China, Hong Kong and Taiwan. In addition, investments in Taiwan could be adversely affected by its political and economic relationship with China. Certain securities issued by companies located or operating in China, such as China A-shares, are subject to trading restrictions, quota limitations and less market liquidity. Reduction in spending on Chinese products and services, institution of additional tariffs or other trade barriers, including as a result of heightened trade tensions between China and the United States, or a downturn in any of the economies of China's key trading partners may have an adverse impact on the Chinese economy.

Additionally, developing countries, such as China, may subject the Fund's investments to a number of tax rules, and the application of many of those rules may be uncertain. Changes in applicable Chinese tax law could reduce the after-tax profits of the Fund, directly or indirectly, including by reducing the after-tax profits of companies in China in which the Fund invests. Uncertainties in Chinese tax rules could result in unexpected tax liabilities for the Fund.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Investments in foreign government bonds involve special risks because the Fund may have limited legal recourse in the event of default. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

China A-shares risk: China A-shares are subject to a number of restrictions imposed by Chinese securities regulations and listing rules. Investments by foreign investors in A-shares are subject to various restrictions, regulations and limits. The A-share market is volatile with a risk of suspension of trading in a particular security or multiple securities or government intervention. The A-shares market can have a higher propensity for trading suspensions than many other global equity markets. Trading suspensions could lead to greater market execution risk, valuation risks, liquidity risks, and costs for the Fund.

Furthermore, any changes in laws, regulations and policies of the China A-shares market or rules in relation to Stock Connect may affect China A-share prices. These risks are heightened by the developing state of the PRC's investment and banking systems in general.

Per a circular (Caishui [2014] 79), the Fund is expected to be temporarily exempt from the Chinese withholding tax ("WHT") on capital gains on trading in A-shares. There is no indication as to how long the temporary exemption will remain in effect. Accordingly, the Fund may be subject to such taxes in the future. If the Fund expects such WHT on trading in A-shares to be imposed, it reserves the right to establish a reserve for such tax, although it currently does not do so. If the Fund establishes such a reserve but is not ultimately subject to the tax, shareholders who redeemed or sold their shares while the reserve was in place will effectively bear the tax and may not benefit from the later release, if any, of the reserve. Conversely, if the Fund does not establish such a reserve but ultimately is subject to the tax, shareholders who redeemed or sold their shares prior to the tax being withheld, reserved or paid will have effectively avoided the tax, even if they benefited from the trading that precipitated the Fund's payment of it. Investors should note that such provision may be excessive or inadequate to meet actual WHT liabilities (which could include interest and penalties) on the Fund's investments. As a result, investors may be advantaged or disadvantaged depending on the final rules of the relevant PRC tax authorities.

Stock Connect investing risk: Investing in A-shares through Stock Connect is subject to trading, clearance, settlement, and other procedures, which could pose risks to the Fund. Trading through the Stock Connect program is subject to daily quotas that limit the maximum daily net purchases on any particular day, each of which may restrict or preclude the Fund's ability to invest in A-shares through the Stock Connect program. A primary feature of the Stock Connect program is the application of the home market's laws and rules applicable to investors in A-shares. Therefore, the Fund's investments in Stock Connect A-shares are generally subject to PRC securities regulations and listing rules, among other restrictions. The Shanghai and Shenzhen markets may be open at a time when the Stock Connect Program is not trading, with the result that prices of China A-shares may fluctuate at times when the Fund is unable to add to or exit its position.

Offshore RMB risk: There is no assurance that there will always be sufficient amounts of RMB (i.e., Chinese currency) available for the Fund to remain fully invested in Chinese equities. The Chinese government heavily regulates the domestic exchange of foreign currencies and RMB exchange rates in China, which may adversely affect the operations and financial results of the Fund's investments in China.

Geographic concentration risk: The risk that if the Fund has most of its investments in a single country or region, its portfolio will be more susceptible to factors adversely affecting issuers located in that country or region than would a more geographically diverse portfolio of securities.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments, and they may have more limited resources.

Non-diversification risk: The Fund is a non-diversified investment company, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company. As a non-diversified fund, the Fund's share price may be more volatile, and the Fund has a greater potential to realize losses upon the occurrence of adverse events affecting a particular issuer.

IPOs risk: The purchase of shares issued in IPOs may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market security. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in other funds risk: The Fund's investment performance is affected by the investment performance of the underlying funds in which the Fund may invest. Through its investment in the underlying funds, the Fund is subject to the risks of the underlying funds' investments and their expenses.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose money by investing in the Fund.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The Fund is a non-diversified investment company, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company. As a non-diversified fund, the Fund's share price may be more volatile, and the Fund has a greater potential to realize losses upon the occurrence of adverse events affecting a particular issuer.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

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Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

There is no performance information quoted for the Fund as the Fund had not commenced investment operations as of the date of this prospectus.

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

There is no performance information quoted for the Fund as the Fund had not commenced investment operations as of the date of this prospectus.

Class A & P Prospectus | UBS All China Equity Fund | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.50%

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Management fees

rr_ManagementFeesOverAssets

0.85%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.60%

^[2]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.70%

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

0.35%

^[3]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

1.35%

^[3]

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 680

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

$ 1,024

Class A & P Prospectus | UBS All China Equity Fund | Class P

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.85%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.60%

^[2]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.45%

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

0.35%

^[3]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

1.10%

^[3]

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 112

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

$ 424

[1] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[2] "Other expenses" are based on estimates for the current fiscal year.

[3] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, extraordinary expenses and dividend expense and security loan fees for securities sold short) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, extraordinary expenses and dividend expense and security loan fees for securities sold short), through the period ending October 28, 2020, do not exceed 1.35% for Class A shares and 1.10% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

XML

Label

Element

Value

UBS International Sustainable Equity Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

UBS International Sustainable Equity Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to maximize total return, consisting of capital appreciation and current income by investing primarily in the equity securities of non-US issuers.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 57% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

57.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 50,000

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the irrevocable fee waiver and expense reimbursement for all years. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Principal investments

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in equity securities. Investments in equity securities may include, but are not limited to, dividend-paying securities, common stock and preferred stock of issuers located throughout the world; equity securities of real estate investment trusts ("REITs"); and exchange-traded funds ("ETFs"). Under normal market conditions, the Fund invests primarily (at least 65% of its total assets) in issuers organized or having their principal place of business outside the United States or doing a substantial amount of business outside the United States. Up to 35% of the Fund's assets may be invested in US equity securities. The Fund may invest in issuers from both developed and emerging markets. The Advisor, on behalf of the Fund, intends to diversify broadly among countries, but reserves the right to invest a substantial portion of the Fund's assets in one or more countries if economic and business conditions warrant such investments. The Fund may invest in stocks of companies of any size.

The Fund may, but is not required to, use exchange-traded or over-the-counter ("OTC") derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include futures, forward currency agreements and equity participation notes. All of these derivatives may be used for risk management purposes to manage or adjust the risk profile of the Fund. Futures on currencies and forward currency agreements may also be used to hedge against a specific currency. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments (except for forward currency agreements); or to obtain exposure to certain markets (except for forward currency agreements). The Fund also may use futures contracts on equity securities and indices to gain market exposure on its uninvested cash.

Under certain market conditions, the Fund may invest in companies at the time of their initial public offering ("IPO").

Management process

The Advisor's investment decisions are based upon price/value discrepancies as identified by the Advisor's fundamental valuation process.

In selecting securities for the portion of the Fund that is managed according to the Advisor's fundamental valuation process, the Advisor focuses on, among other things, identifying discrepancies between a security's fundamental value and its market price. In this context, the fundamental value of a given security is the Advisor's assessment of what a security is worth. The Advisor will select a security whose fundamental value it estimates to be greater than its market value at any given time. For each stock under analysis, the Advisor bases its estimates of value upon country, economic, industry and company analysis, as well as upon a company's management team, competitive advantage and core competencies. The Advisor then compares its assessment of a security's value against the prevailing market prices, with the aim of constructing a portfolio of stocks across industries and countries with attractive relative price/value characteristics.

The Advisor will employ both a positive and negative screening process with regard to securities selection for the Fund. The negative screening process will exclude securities with more than 5% of sales in alcohol, tobacco, defense, nuclear, GMO (Genetically Modified Organisms), gambling and pornography from the Fund's portfolio. We believe that this negative screen reduces the global universe by about 7% by market capitalization, and we do not expect it to have a material impact on portfolio construction or strategy. The Advisor may modify the above list of negative screens at any time, without prior shareholder approval or notice.

The positive screening process will identify securities of companies that are attractive based on their fundamental and valuation profile in addition to evaluating specific sustainability factors.

These sustainability factors are material factors that help the Advisor evaluate and compare the environmental, social and governance performance of the investable universe. This information is combined with additional financial analysis and research to identify companies the Advisor believes will provide attractively valued and sustainable investment opportunities.

Risk [Heading]

rr_RiskHeading

Main risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

Sustainability factor risk: The Fund's sustainability factors used in its investment process will likely make the Fund perform differently from a fund that relies solely or primarily on financial metrics. The sustainability factors may cause the Fund's industry allocation to deviate from that of funds without these considerations.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments, and they may have more limited resources.

IPOs risk: The purchase of shares issued in IPOs may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market securities. In addition, non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

Risk/return bar chart and table

The performance information that follows shows the Fund's performance information in a bar chart and an average annual total returns table. The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance. Indicies reflect no deduction for fees and expenses. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. In October 2013, the Fund's investment strategies changed. The performance below for periods prior to that date is attributable to the Fund's performance before the strategy change. Updated performance for the Fund is available at www.ubs.com/us-mutualfundperformance.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.ubs.com/us-mutualfundperformance

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total return (Class P)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Total return January 1 - September 30, 2019: 11.17%
Best quarter during calendar years shown—2Q 2009: 29.94%
Worst quarter during calendar years shown—3Q 2011: (23.88)%

Year to Date Return, Label

rr_YearToDateReturnLabel

Total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

11.17%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

29.94%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(23.88%)

Performance Table Market Index Changed

rr_PerformanceTableMarketIndexChanged

Effective October 28, 2019, the MSCI ACWI ex-US Index replaced MSCI World ex USA Index (net) as the Fund's primary benchmark because it more closely aligns with the Fund's investment strategy.

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

Indicies reflect no deduction for fees and expenses.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

Average annual total returns (figures reflect sales charges) (for the periods ended December 31, 2018)

UBS International Sustainable Equity Fund | MSCI ACWI ex-US Index

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(14.20%)

^[1]

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.68%

^[1]

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

6.57%

^[1]

UBS International Sustainable Equity Fund | MSCI World ex USA Index (net)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(14.09%)

^[1]

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.34%

^[1]

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

6.24%

^[1]

UBS International Sustainable Equity Fund | CLASS A

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.50%

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[2]

Management fees

rr_ManagementFeesOverAssets

0.80%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.48%

^[3]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.53%

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

0.28%

^[4]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

1.25%

^[4]

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 670

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

925

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,199

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,978

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(21.48%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

1.06%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

6.35%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 30, 1997

UBS International Sustainable Equity Fund | CLASS P

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.80%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.46%

^[3]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.26%

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

0.26%

^[4]

Total annual fund operating expenses after management fee waiver/expense reimbursements

rr_NetExpensesOverAssets

1.00%

^[4]

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 102

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

318

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

552

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,225

Annual Return 2009

rr_AnnualReturn2009

39.65%

Annual Return 2010

rr_AnnualReturn2010

12.39%

Annual Return 2011

rr_AnnualReturn2011

(17.79%)

Annual Return 2012

rr_AnnualReturn2012

18.80%

Annual Return 2013

rr_AnnualReturn2013

15.87%

Annual Return 2014

rr_AnnualReturn2014

5.40%

Annual Return 2015

rr_AnnualReturn2015

(1.12%)

Annual Return 2016

rr_AnnualReturn2016

(0.80%)

Annual Return 2017

rr_AnnualReturn2017

31.21%

Annual Return 2018

rr_AnnualReturn2018

(16.71%)

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(16.71%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

2.47%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

7.21%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Aug. 31, 1993

UBS International Sustainable Equity Fund | CLASS P | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(16.98%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

2.17%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

6.66%

UBS International Sustainable Equity Fund | CLASS P | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(9.49%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

2.01%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

5.87%

[1] Effective October 28, 2019, the MSCI ACWI ex-US Index replaced MSCI World ex USA Index (net) as the Fund's primary benchmark because it more closely aligns with the Fund's investment strategy.

[2] Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

[3] "Other expenses" include "Acquired fund fees and expenses," which were less than 0.01% of the average net assets of the Fund.

[4] UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), has agreed irrevocably to waive its fees and reimburse certain expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) do not exceed 1.25% for Class A shares and 1.00% for Class P shares. This fee waiver and expense arrangement may only be amended or terminated by shareholders.

XML

UBS Municipal Bond Fund

UBS Municipal Bond Fund

Investment objective

The Fund seeks to provide total return consisting of capital appreciation and current income exempt from federal income tax.

Fees and expenses

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $100,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" beginning on page 128 of this prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" beginning on page 101 of the Fund's statement of additional information ("SAI"). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A-1 of this prospectus.

Shareholder fees (fees paid directly from your investment)

Shareholder Fees - UBS Municipal Bond Fund	Class A		Class P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	2.25%		none
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	none	[1]	none

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - UBS Municipal Bond Fund		Class A	Class P
Management fees		0.40%	0.40%
Distribution and/or service (12b-1) fees		0.25%	none
Other expenses	[1]	0.42%	0.42%
Total annual fund operating expenses		1.07%	0.82%
Less management fee waiver/expense reimbursements	[2]	0.42%	0.42%
Total annual fund operating expenses after management fee waiver/expense reimbursements	[2]	0.65%	0.40%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example - UBS Municipal Bond Fund - USD ($)	1 year	3 years	5 years	10 years
Class A	290	517	762	1,464
Class P	41	220	414	974

Portfolio turnover

The Fund pays transaction costs, such as mark-ups, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 31% of the average value of its portfolio.

Principal strategies

Principal investments

Under normal circumstances, the Fund will invest at least 80% of its net assets (plus borrowings for investment purposes, if any) in municipal bonds and other investments with similar economic characteristics, the interest on which is exempt from regular federal income tax. The Fund primarily invests in securities that, at the time of purchase, are rated investment grade by an independent rating agency (or if unrated are deemed to be of comparable quality by the Advisor), but may invest up to 10% in securities rated below investment grade (also known as "junk bonds"). The Fund may also, to a lesser extent, invest in US Treasury securities and other securities of the US government, its agencies and government-sponsored enterprises. The Fund is a non-diversified fund, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company.

The Fund's weighted average portfolio duration will normally range between 3 and 10 years, but the Fund generally targets a duration of between 4.5 and 7 years. The Fund may invest in bonds of any maturity or duration.

The Fund may invest in insured and uninsured municipal securities. The Fund's investments may include, but are not limited to, general obligation and revenue bonds, tax-exempt commercial paper, short-term municipal notes, tender option bonds (including inverse floaters), floating and variable rate demand obligations, and other municipal securities that pay income exempt from federal income tax. The Fund does not intend to invest substantially in securities whose interest is subject to the federal alternative minimum tax.

The Fund may, but is not required to, use exchange traded or over-the-counter ("OTC") derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include interest rate and credit instruments such as options (including, options on futures and swap agreements), futures, swap agreements (including, interest rate, total return, and credit default swaps), credit-linked securities and structured investments. All of these derivatives may be used for risk management purposes, such as hedging against a specific security, or to manage or adjust the risk profile of the Fund. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments; to obtain exposure to certain markets; to establish net short positions for individual sectors, markets or securities; or to adjust the Fund's portfolio duration.

The Fund may invest in exchange-traded funds ("ETFs") to gain exposure to certain asset classes.

Management process

The Advisor adheres to a disciplined top-down and bottom-up investment process that seeks to leverage information advantage by using a proprietary credit research framework while focusing on three key decisions: duration, sector allocation and security selection. The investment process begins with an in-depth analysis of top-down inputs to determine the correct duration positioning of the portfolio. These inputs originate from the Advisor's proprietary research on the structure of the yield curve and its relationship to the US Treasury market. The Advisor's sector allocation analysis determines the attractiveness of various segments of the municipal market with a focus on two main themes—bond security (e.g., state vs. local general obligation bonds) and essential services (e.g., water and sewer systems or electric utilities). Security selection represents the final level of decision-making in the Advisor's investment process. The Advisor uses rigorous credit/structure analysis and relative pricing to select securities that the Advisor believes demonstrate superior risk/return characteristics. The Advisor then seeks to select individual securities that will provide the portfolio the desired sector and duration exposures at the lowest cost.

Main risks

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Municipal securities risk: Municipal securities are subject to interest rate and credit risks. The ability of a municipal issuer to make payments and the value of municipal securities can be affected by uncertainties in the municipal securities market. Such uncertainties could cause increased volatility in the municipal securities market and could negatively impact the fund's net asset value and/or the distributions paid by the fund. Municipal bonds secured by revenues from public housing authorities may be subject to additional uncertainties relating to the possibility that proceeds may exceed supply of available mortgages to be purchased by public housing authorities, resulting in early retirement of bonds, or that homeowner repayments will create an irregular cash flow. Municipalities continue to experience difficulties in the current economic and political environment.

Interest rate risk: An increase in prevailing interest rates typically causes the value of fixed income securities to fall. Changes in interest rates will likely affect the value of longer-duration fixed income securities more than shorter-duration securities and higher quality securities more than lower quality securities. When interest rates are falling, some fixed income securities provide that the issuer may repay them earlier than the maturity date, and if this occurs the Fund may have to reinvest these repayments at lower interest rates. The Fund may face a heightened level of interest rate risk due to certain changes in monetary policy, such as certain types of interest rate changes by the Federal Reserve.

Credit risk: The risk that the Fund could lose money if the issuer or guarantor of a fixed income security, or the counterparty to or guarantor of a derivative contract, is unable or unwilling to meet its financial obligations. This risk is likely greater for lower quality investments than for investments that are higher quality.

Prepayment or call risk: The risk that issuers will prepay fixed rate obligations when interest rates fall, forcing the Fund to reinvest in obligations with lower interest rates than the original obligations. When interest rates are rising, slower prepayments may extend the duration of the securities and may reduce their value.

Political risk: The Fund's investments may be significantly affected by political changes, including legislative proposals that may make municipal bonds less attractive in comparison to taxable bonds or other types of investments.

Tax liability risk: Tax liability risk is the risk of noncompliant conduct by a municipal bond issuer, resulting in distributions by the Fund being taxable to shareholders as ordinary income.

Related securities concentration risk: Because the Fund may invest more than 25% of its net assets in municipal bonds that are issued to finance similar projects, economic, business, or political developments or changes that affect one municipal bond also may affect other municipal bonds in the same sector.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Variable rate demand obligations risk: Variable rate demand obligations are floating rate securities that combine an interest in a long-term municipal bond with a right to demand payment before maturity from a bank or other financial institution. If the bank or financial institution is unable to pay, the Fund may lose money. The absence of an active secondary market for certain variable and floating rate obligations could make it difficult to dispose of these instruments, which could result in a loss.

US Government securities risk: There are different types of US government securities with different levels of credit risk, including risk of default, depending on the nature of the particular government support for that security. For example, a US government-sponsored entity, although chartered or sponsored by an Act of Congress, may issue securities that are neither insured nor guaranteed by the US Treasury and are therefore riskier than those that are.

High yield bond risk: The risk that the issuer of municipal bonds with ratings of Ba1 or lower by Moody's Investors Service, Inc. ("Moody's") or BB+ or lower by Standard & Poor's Financial Services LLC ("S&P") or Fitch Ratings, Inc. ("Fitch"), comparably rated by another nationally recognized statistical rating organization, or, if unrated, are determined to be of comparable quality by the Advisor, will default or otherwise be unable to honor a financial obligation (also known as lower-rated or "junk bonds"). These securities are considered to be predominately speculative with respect to an issuer's capacity to pay interest and repay principal in accordance with the terms of the obligations. Lower-rated municipal bonds are more likely to be subject to an issuer's default or downgrade than investment grade (higher quality) municipal bonds.

Non-diversification risk: The Fund is a non-diversified investment company, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company. As a non-diversified fund, the Fund's share price may be more volatile and the Fund has a greater potential to realize losses upon the occurrence of adverse events affecting a particular issuer.

Market risk: The risk that the market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market securities.

Derivatives relating to fixed income markets are especially susceptible to interest rate risk and credit risk. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Performance

Risk/return bar chart and table

The performance information that follows shows the Fund's performance information in a bar chart and an average annual total returns table. The information provides some indication of the risks of investing in the Fund by showing the Fund's performance from year to year and by showing how the Fund's average annual total returns compare with those of a broad measure of market performance. The Bloomberg Barclays Municipal Bond Index shows how the Fund's performance compares to an index that is designed to measure the fixed income market performance of the tax-exempt bond market. The Bloomberg Barclays Municipal Managed Money Intermediate (1-17) Index compares the Fund's performance to an index that measures the performance of municipal securities issued by state and local municipalities whose interest is exempt from both federal income tax and the federal alternative minimum tax. Indices reflect no deduction for fees, expenses or taxes. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Updated performance for the Fund is available at www.ubs.com/us-mutualfundperformance.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for other classes will vary from the Class P shares' after-tax returns shown.

Total return (Class P)*

* 2015 is the Fund's first full year of operations.

Total return January 1 - September 30, 2019: 7.27%
Best quarter during calendar year shown—2Q 2016: 2.38%
Worst quarter during calendar year shown—4Q 2016: (3.44)%

Average annual total returns (figures reflect sales charges) (for the periods ended December 31, 2018)

Average Annual Returns - UBS Municipal Bond Fund	Average Annual Returns, 1 Year	Average Annual Returns, Since Inception	Average Annual Returns, Inception Date
Class A	(1.58%)	1.47%	Nov. 10, 2014
Class P	0.98%	2.26%	Nov. 10, 2014
After Taxes on Distributions | Class P	0.98%	2.24%
After Taxes on Distributions and Sale of Fund Shares | Class P	1.37%	2.16%
Bloomberg Barclays Municipal Bond Index	1.28%	2.70%
Bloomberg Barclays Municipal Managed Money Intermediate (1-17) Index	1.22%	2.40%

[1] Purchases of $500,000 or more that were not subject to a front-end sales charge are subject to a 0.75% CDSC if sold within one year of the purchase date.

[1] "Other expenses" include "Acquired fund fees and expenses," which were less than 0.01% of the average net assets of the Fund.

[2] The Trust, with respect to the Fund, and UBS Asset Management (Americas) Inc., the Fund's investment advisor ("UBS AM (Americas)" or the "Advisor"), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses), through the period ending October 28, 2020, do not exceed 0.65% for Class A shares and 0.40% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement, or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)'s three year recoupment rights will survive.

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Class P2 Prospectus | UBS Sustainable Development Bank Bond Fund

UBS Sustainable Development Bank Bond Fund

Investment objective

The Fund seeks current income.

Fees and expenses

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. Shares of Class P2 are available for purchase on behalf of clients of a fee-based program or certain other advisory programs in which UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), exercises investment discretion. Clients pay a wrap fee or a similar advisory fee to participate in such programs. Shares of Class P2 are also available for purchase on behalf of institutional clients with which the Advisor or its affiliates has signed a separate investment management agreement, pursuant to which such clients pay an advisory fee.

Shareholder fees (fees paid directly from your investment)

Shareholder Fees	Class P2 Prospectus UBS Sustainable Development Bank Bond Fund Class P2
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	none
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	none

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Class P2 Prospectus UBS Sustainable Development Bank Bond Fund Class P2
Management fees	0.15%
Distribution and/or service (12b-1) fees	none
Other expenses	2.04%	[1]
Total annual fund operating expenses	2.19%
Less management fee waiver/expense reimbursements	2.04%	[2]
Total annual fund operating expenses after management fee waiver/expense reimbursement	0.15%	[2]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example	1 year	3 years	5 years	10 years
Class P2 Prospectus | UBS Sustainable Development Bank Bond Fund | Class P2 | USD ($)	15	488	987	2,363

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. For the period October 24, 2018 (commencement of operations) through June 30, 2019, the Fund's portfolio turnover rate was 20%.

Principal strategies

Principal investments

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in bonds and/or instruments that provide exposure to bonds issued by development banks. Development banks are financial organizations formed by government entities to promote economic and social development. The Fund invests in multilateral development bank bonds but may also invest in regional or national development bank obligations. The Fund's investment in obligations issued by the International Bank for Reconstruction and Development and the Inter-American Development Bank may be significant, but the Fund normally will not invest more than 25% of its net assets in either issuer.

Under normal circumstances, the Fund will invest in securities that, at the time of purchase, possess a minimum rating of A3 by Moody's Investors Service, Inc. ("Moody's") or A- by Standard & Poor's Financial Services LLC ("S&P") or Fitch Ratings, Inc. ("Fitch"), comparably rated by another nationally recognized statistical rating organization, or, if unrated, are determined by the Advisor to be of comparable quality.

The Fund's investments in fixed income securities may have all types of interest rate payment and reset terms. The Fund generally invests only in US dollar-denominated securities.

The Fund may, but is not required to, engage in derivatives transactions. Derivatives instruments such as futures may be used for risk management purposes to hedge against a specific security or for investment (non-hedging) purposes to earn income or adjust portfolio duration. The Fund does not seek to use derivatives extensively.

The Fund may invest in exchange-traded funds ("ETFs") to gain exposure to certain asset classes.

The Fund is a non-diversified fund, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company.

Management process

The Advisor seeks to invest in bonds issued by development banks. The Advisor constructs the portfolio consisting of multilateral and regional development banks. The Advisor focuses primarily on bonds issued by multilateral development banks which may include, but are not limited to, the International Bank for Reconstruction and Development and other member institutions of the World Bank Group, the Inter-American Development Bank, the Asian Development Bank, the African Development Bank, and the European Bank for Reconstruction and Development. Development banks are formed by their member states with the objective to provide financial and technical assistance to improve overall living standards through sustainable economic development and growth. While each development bank has a distinct focus, development banks generally use their capital for projects that seek to improve the state of the developing world, promote sustainable growth and raise living standards.

The Advisor selects investments for the Fund based on available supply and liquidity parameters (including, for example, such factors as evaluating amounts outstanding, available dealer inventory, and volumes traded in the secondary market) utilizing a stratified sampling approach (investing in a representative cross-section of the investment universe) to optimize tracking error and minimize transaction cost. The Fund will be managed relative to a composite index, which is a blend of two market indexes designed to measure the performance of the US dollar denominated multilateral development bank bond market. The Fund does not seek to directly replicate the index. The Fund's composite index is the Solactive UBS Global Multilateral Development Bank Bond USD 40% 1-5 Year 60% 5-10 Year Total Return Index. (The Fund reserves the right in its discretion to change the index). The Fund's development bank bond investments may include issuers that are not part of the composite index. The Fund will seek to maintain a concentrated portfolio of development bank bonds emphasizing multilateral development banks. The portfolio management team will select the bonds in the market that meet their selection criteria with intention to provide similar risk/return characteristics as the broader development bank bond market.

The Fund may engage in active trading to adjust the portfolio in response to investor activity and to rebalance the portfolio as new development bank issuers come to the market and existing issuers enter the index or mature.

Main risks

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Risks of development bank bonds: The value of the Fund's investments in bonds issued by development banks may fall due to adverse financial market developments in the United States and abroad. Borrowers from development banks include foreign countries, which may include emerging market countries, and borrowers of specific development banks also include the private sector with or without government guarantee. Therefore, negative economic, social and political developments could affect the ability of a borrower to repay its loan to the development bank and thus affect its financial condition. In addition, investments in such development bank bonds may involve special risks because the Fund may have limited legal recourse in the event of default. Also, development bank bonds may sometimes be less liquid and more difficult to sell and to value than high-quality securities of US issuers. Bonds issued by a development bank are backed by the shareholders of the development bank. The development bank may be supported via various mechanisms including, preferred creditor status, equity injections by its shareholders and callable capital, even though the latter may have never been tested with respect to an issuer. Changes in the shareholder structure of a development bank or changes in the strength of the support by its shareholders could affect the credit rating and thus the value of the bonds issued by the development bank.

Concentration risk: The Fund concentrates in the bonds of development banks. The risk that if the Fund has most of its investments in a single industry, its portfolio will be more susceptible to factors adversely affecting that industry than would a more diverse portfolio of securities.

Interest rate risk: An increase in prevailing interest rates typically causes the value of fixed income securities to fall. Changes in interest rates will likely affect the value of longer-duration fixed income securities more than shorter-duration securities and higher quality securities more than lower quality securities. When interest rates are falling, some fixed income securities provide that the issuer may repay them earlier than the maturity date, and if this occurs the Fund may have to reinvest these repayments at lower interest rates. The Fund may face a heightened level of interest rate risk due to certain changes in monetary policy, such as certain types of interest rate changes by the Federal Reserve.

Credit risk: The risk that the Fund could lose money if the issuer or guarantor of a fixed income security, or the counterparty to or guarantor of a derivative contract, is unable or unwilling to meet its financial obligations. This risk is likely greater for lower quality investments than for investments that are higher quality.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Non-diversification risk: The Fund is a non-diversified investment company, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company. As a non-diversified fund, the Fund's share price may be more volatile, and the Fund has a greater potential to realize losses upon the occurrence of adverse events affecting a particular issuer.

Portfolio turnover risk: High portfolio turnover from frequent trading will increase the Fund's transaction costs and may increase the portion of the Fund's capital gains that are realized for tax purposes in any given year. The Fund does not restrict the frequency of trading in order to limit expenses or the tax effect that its distributions may have on shareholders.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market security. Derivatives relating to fixed income markets are especially susceptible to interest rate risk and credit risk. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Performance

There is no performance information quoted for the Fund as the Fund had not yet completed a full calendar year of operations as of the date of this prospectus.

[1] "Other expenses" are based on estimates for the current fiscal year. "Other expenses" include "Acquired fund fees and expenses," which were less than 0.01% of the average net assets of the Fund.

[2] The Trust, with respect to the Fund, and the Advisor, have entered into a written agreement pursuant to which the Advisor has agreed to waive its management fees and retained administration fees, and to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) through the period ending October 28, 2020 do not exceed 0.15%. Pursuant to the expense limitation agreement, the Advisor is entitled to be reimbursed for any expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the reimbursement or (ii) at the time of the recoupment. The expense limitation agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the expense limitation agreement, however, the Advisor's three year recoupment rights will survive.

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Class P2 Prospectus | UBS All China Equity Fund

UBS All China Equity Fund

Investment objective

The Fund seeks to maximize capital appreciation.

Fees and expenses

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. Shares of Class P2 are available for purchase on behalf of clients of a fee-based program or certain other advisory programs in which UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor") exercises investment discretion. Clients pay a wrap fee or a similar advisory fee to participate in such programs. Shares of Class P2 are also available for purchase on behalf of institutional clients with which the Advisor or its affiliates has signed a separate investment management agreement, pursuant to which such clients pay an advisory fee.

Shareholder fees (fees paid directly from your investment)

Shareholder Fees	Class P2 Prospectus UBS All China Equity Fund Class P2
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	none
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	none

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Class P2 Prospectus UBS All China Equity Fund Class P2
Management fees	0.85%
Distribution and/or service (12b-1) fees	none
Other expenses	0.60%	[1]
Total annual fund operating expenses	1.45%
Less management fee waiver/expense reimbursements	1.15%	[2]
Total annual fund operating expenses after management fee waiver/expense reimbursement	0.30%	[2]

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the reduction in the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example	1 year	3 years
Class P2 Prospectus | UBS All China Equity Fund | Class P2 | USD ($)	31	345

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. Because the Fund had not yet commenced operations as of the date of this prospectus, it does not have a portfolio turnover rate to provide.

Principal strategies

Principal investments

The Advisor seeks to achieve the Fund's investment objective by investing, under normal circumstances, at least 80% of the Fund's net assets (plus borrowings for investment purposes, if any) in a portfolio of equity securities of companies economically tied to China, and in other instruments that have economic characteristics similar to such securities. For this purpose, China includes the People's Republic of China ("PRC") and Hong Kong. A security will be considered to be economically tied to China if it: (i) is issued or guaranteed by a government of China or any of its agencies, political subdivisions or instrumentalities; (ii) has its primary trading market in China; (iii) is issued by an entity organized under the laws of, derives at least 50% of its revenues from, or has at least 50% of its assets in China; (iv) is included in an index representative of China; or (v) is exposed to the economic fortunes and risks of China.

Equity securities may include common stocks; preferred stocks; equity securities of real estate investment trusts ("REITs"); shares of other investment companies, including exchange-traded funds ("ETFs"); depositary receipts; and derivative instruments related to equity securities, including equity participation notes, options and futures on individual securities and indexes. The Fund's investments may include investments in securities of companies listed on exchanges located in and outside of the PRC, including but not limited to the Hong Kong Stock Exchange, Taiwan Stock Exchange, Singapore Exchange, the New York Stock Exchange, and London Stock Exchange. The Fund's investments also include China A-shares. China A-shares are equity securities issued by companies incorporated in mainland China and are denominated and traded in renminbi ("RMB") on the Shenzhen and Shanghai Stock Exchanges through the Shanghai-Hong Kong Stock Connect program and the Shenzhen-Hong Kong Stock Connect program (collectively, "Stock Connect").

The Fund may invest in companies of any size. The Fund is a non-diversified fund, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company.

The Advisor believes that discrepancies between market price and fair value arise from market behavior and market structure, and these discrepancies provide opportunities to outperform the market. To take advantage of these opportunities, the Advisor seeks to identify upcoming industry leaders in key secular growth sectors early in the company's lifecycle and when the company's share price trades far below our estimate of the firm's fair value.

The Advisor adopts a benchmark agnostic approach (meaning that the Advisor selects companies without the benchmark by which the Fund measures performance (the MSCI All China Index) being determinative), and the Fund may have a wider deviation from the benchmark than other funds. This is expected to enable the Advisor to identify non-benchmark companies with stronger long-term growth potential than might otherwise be the case.

The Fund may, but is not required to, use exchange-traded or over-the-counter derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include options (including options on securities, indices, futures, forwards, and swap agreements), futures, forward currency agreements, swap agreements (including interest rate, total return and currency) and equity participation notes and equity linked notes. All of these derivatives may be used for risk management purposes to manage or adjust the risk profile of the Fund. Futures on currencies and forward currency agreements may also be used to hedge against a specific currency. Further, the Fund may acquire and sell forward foreign currency exchange contracts in order to attempt to protect against uncertainty in the level of future foreign currency exchange rates in connection with the settlement of securities. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments (except for forward currency agreements); to obtain exposure to certain markets; or to establish net short positions for individual currencies (except for equity participation notes).

Under certain market conditions, the Fund may invest in companies at the time of their initial public offering ("IPO").

Management process

The investment process for the All China strategy is driven by bottom-up proprietary research. As a starting point, the investment universe includes all investable quoted equities domiciled in China and/or of issuers generating the majority of their income in China. The investment team is expected to exclude companies exhibiting what we view as unsustainable business models, poor corporate governance practices, and negative industry dynamics. In order to form a qualitative assessment of a company, the Advisor scores companies based on a set of questions covering three areas:

1. Industry Structure and Company's Competitiveness

2. Trends & Profitability: Trends and Sustainability

3. Governance, disclosure, environmental and social practices

The Advisor further conducts extensive valuation analysis incorporating company/industry fundamentals, future operations, and cash generation. Peer comparisons and valuation bands are also studied based on historical and forward looking financials.

The Advisor seeks to construct a "best ideas," concentrated, high-conviction portfolio. The companies would be selected based on the attractiveness of their valuations, top down macro factors, and a conviction that the investment thesis is likely to be realized. Positions would be assigned weights based on the investment parameters for the strategy and the portfolio manager's conviction in the investment thesis. The Advisor aims to construct a portfolio diversified across many sectors with no single stock position being greater than 10% of the portfolio.

Main risks

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

China risk: There are special risks associated with investments in China, Hong Kong and Taiwan, including exposure to currency fluctuations, less liquidity, expropriation, confiscatory taxation, nationalization and exchange control regulations (including currency blockage). Inflation and rapid fluctuations in inflation and interest rates have had, and may continue to have, negative effects on the economy and securities markets of China, Hong Kong and Taiwan. In addition, investments in Taiwan could be adversely affected by its political and economic relationship with China. Certain securities issued by companies located or operating in China, such as China A-shares, are subject to trading restrictions, quota limitations and less market liquidity. Reduction in spending on Chinese products and services, institution of additional tariffs or other trade barriers, including as a result of heightened trade tensions between China and the United States, or a downturn in any of the economies of China's key trading partners may have an adverse impact on the Chinese economy.

Additionally, developing countries, such as China, may subject the Fund's investments to a number of tax rules, and the application of many of those rules may be uncertain. Changes in applicable Chinese tax law could reduce the after-tax profits of the Fund, directly or indirectly, including by reducing the after-tax profits of companies in China in which the Fund invests. Uncertainties in Chinese tax rules could result in unexpected tax liabilities for the Fund.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Investments in foreign government bonds involve special risks because the Fund may have limited legal recourse in the event of default. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

China A-shares risk: China A-shares are subject to a number of restrictions imposed by Chinese securities regulations and listing rules. Investments by foreign investors in A-shares are subject to various restrictions, regulations and limits. The A-share market is volatile with a risk of suspension of trading in a particular security or multiple securities or government intervention. The A-shares market can have a higher propensity for trading suspensions than many other global equity markets. Trading suspensions could lead to greater market execution risk, valuation risks, liquidity risks, and costs for the Fund.

Furthermore, any changes in laws, regulations and policies of the China A-shares market or rules in relation to Stock Connect may affect China A-share prices. These risks are heightened by the developing state of the PRC's investment and banking systems in general.

Per a circular (Caishui [2014] 79), the Fund is expected to be temporarily exempt from the Chinese withholding tax ("WHT") on capital gains on trading in A-shares. There is no indication as to how long the temporary exemption will remain in effect. Accordingly, the Fund may be subject to such taxes in the future. If the Fund expects such WHT on trading in A-shares to be imposed, it reserves the right to establish a reserve for such tax, although it currently does not do so. If the Fund establishes such a reserve but is not ultimately subject to the tax, shareholders who redeemed or sold their shares while the reserve was in place will effectively bear the tax and may not benefit from the later release, if any, of the reserve. Conversely, if the Fund does not establish such a reserve but ultimately is subject to the tax, shareholders who redeemed or sold their shares prior to the tax being withheld, reserved or paid will have effectively avoided the tax, even if they benefited from the trading that precipitated the Fund's payment of it. Investors should note that such provision may be excessive or inadequate to meet actual WHT liabilities (which could include interest and penalties) on the Fund's investments. As a result, investors may be advantaged or disadvantaged depending on the final rules of the relevant PRC tax authorities.

Stock Connect investing risk: Investing in A-shares through Stock Connect is subject to trading, clearance, settlement, and other procedures, which could pose risks to the Fund. Trading through the Stock Connect program is subject to daily quotas that limit the maximum daily net purchases on any particular day, each of which may restrict or preclude the Fund's ability to invest in A-shares through the Stock Connect program. A primary feature of the Stock Connect program is the application of the home market's laws and rules applicable to investors in A-shares. Therefore, the Fund's investments in Stock Connect A-shares are generally subject to PRC securities regulations and listing rules, among other restrictions. The Shanghai and Shenzhen markets may be open at a time when the Stock Connect Program is not trading, with the result that prices of China A-shares may fluctuate at times when the Fund is unable to add to or exit its position.

Offshore RMB risk: There is no assurance that there will always be sufficient amounts of RMB (i.e., Chinese currency) available for the Fund to remain fully invested in Chinese equities. The Chinese government heavily regulates the domestic exchange of foreign currencies and RMB exchange rates in China, which may adversely affect the operations and financial results of the Fund's investments in China.

Geographic concentration risk: The risk that if the Fund has most of its investments in a single country or region, its portfolio will be more susceptible to factors adversely affecting issuers located in that country or region than would a more geographically diverse portfolio of securities.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments, and they may have more limited resources.

Non-diversification risk: The Fund is a non-diversified investment company, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company. As a non-diversified fund, the Fund's share price may be more volatile, and the Fund has a greater potential to realize losses upon the occurrence of adverse events affecting a particular issuer.

IPOs risk: The purchase of shares issued in IPOs may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market security. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in other funds risk: The Fund's investment performance is affected by the investment performance of the underlying funds in which the Fund may invest. Through its investment in the underlying funds, the Fund is subject to the risks of the underlying funds' investments and their expenses.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Performance

There is no performance information quoted for the Fund as the Fund had not commenced investment operations as of the date of this prospectus.

[1] "Other expenses" are based on estimates for the current fiscal year.

[2] The Trust, with respect to the Fund, and the Advisor, have entered into a written agreement pursuant to which the Advisor has agreed to waive its management fees and retained administration fees, and to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, extraordinary expenses and dividend expense and security loan fees for securities sold short) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, extraordinary expenses and dividend expense and security loan fees for securities sold short) through the period ending October 28, 2020 do not exceed 0.30%. Pursuant to the expense limitation agreement, the Advisor is entitled to be reimbursed for any expenses it reimburses to the extent such reimbursement can be made during the three years following the period during which such expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the reimbursement or (ii) at the time of the recoupment. The expense limitation agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the expense limitation agreement, however, the Advisor's three year recoupment rights will survive.

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Class P2 Prospectus | UBS All China Equity Fund

Risk/Return:

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Risk/Return [Heading]

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UBS All China Equity Fund

Objective [Heading]

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Investment objective

Objective, Primary [Text Block]

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The Fund seeks to maximize capital appreciation.

Expense [Heading]

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Fees and expenses

Expense Narrative [Text Block]

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These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. Shares of Class P2 are available for purchase on behalf of clients of a fee-based program or certain other advisory programs in which UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor") exercises investment discretion. Clients pay a wrap fee or a similar advisory fee to participate in such programs. Shares of Class P2 are also available for purchase on behalf of institutional clients with which the Advisor or its affiliates has signed a separate investment management agreement, pursuant to which such clients pay an advisory fee.

Shareholder Fees Caption [Text]

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Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

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Oct. 28, 2020

Portfolio Turnover [Heading]

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Portfolio turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. Because the Fund had not yet commenced operations as of the date of this prospectus, it does not have a portfolio turnover rate to provide.

Other Expenses, New Fund, Based on Estimates [Text]

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"Other expenses" are based on estimates for the current fiscal year.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the reduction in the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Strategy [Heading]

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Principal strategies

Strategy Narrative [Text Block]

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Principal investments

The Advisor seeks to achieve the Fund's investment objective by investing, under normal circumstances, at least 80% of the Fund's net assets (plus borrowings for investment purposes, if any) in a portfolio of equity securities of companies economically tied to China, and in other instruments that have economic characteristics similar to such securities. For this purpose, China includes the People's Republic of China ("PRC") and Hong Kong. A security will be considered to be economically tied to China if it: (i) is issued or guaranteed by a government of China or any of its agencies, political subdivisions or instrumentalities; (ii) has its primary trading market in China; (iii) is issued by an entity organized under the laws of, derives at least 50% of its revenues from, or has at least 50% of its assets in China; (iv) is included in an index representative of China; or (v) is exposed to the economic fortunes and risks of China.

Equity securities may include common stocks; preferred stocks; equity securities of real estate investment trusts ("REITs"); shares of other investment companies, including exchange-traded funds ("ETFs"); depositary receipts; and derivative instruments related to equity securities, including equity participation notes, options and futures on individual securities and indexes. The Fund's investments may include investments in securities of companies listed on exchanges located in and outside of the PRC, including but not limited to the Hong Kong Stock Exchange, Taiwan Stock Exchange, Singapore Exchange, the New York Stock Exchange, and London Stock Exchange. The Fund's investments also include China A-shares. China A-shares are equity securities issued by companies incorporated in mainland China and are denominated and traded in renminbi ("RMB") on the Shenzhen and Shanghai Stock Exchanges through the Shanghai-Hong Kong Stock Connect program and the Shenzhen-Hong Kong Stock Connect program (collectively, "Stock Connect").

The Fund may invest in companies of any size. The Fund is a non-diversified fund, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company.

The Advisor believes that discrepancies between market price and fair value arise from market behavior and market structure, and these discrepancies provide opportunities to outperform the market. To take advantage of these opportunities, the Advisor seeks to identify upcoming industry leaders in key secular growth sectors early in the company's lifecycle and when the company's share price trades far below our estimate of the firm's fair value.

The Advisor adopts a benchmark agnostic approach (meaning that the Advisor selects companies without the benchmark by which the Fund measures performance (the MSCI All China Index) being determinative), and the Fund may have a wider deviation from the benchmark than other funds. This is expected to enable the Advisor to identify non-benchmark companies with stronger long-term growth potential than might otherwise be the case.

The Fund may, but is not required to, use exchange-traded or over-the-counter derivative instruments for risk management purposes or as part of the Fund's investment strategies. Generally, derivatives are financial contracts whose value depends upon, or is derived from, the value of an underlying asset, reference rate, index or other market factor and may relate to stocks, bonds, interest rates, credit, currencies or currency exchange rates, commodities and related indexes. The derivatives in which the Fund may invest include options (including options on securities, indices, futures, forwards, and swap agreements), futures, forward currency agreements, swap agreements (including interest rate, total return and currency) and equity participation notes and equity linked notes. All of these derivatives may be used for risk management purposes to manage or adjust the risk profile of the Fund. Futures on currencies and forward currency agreements may also be used to hedge against a specific currency. Further, the Fund may acquire and sell forward foreign currency exchange contracts in order to attempt to protect against uncertainty in the level of future foreign currency exchange rates in connection with the settlement of securities. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments (except for forward currency agreements); to obtain exposure to certain markets; or to establish net short positions for individual currencies (except for equity participation notes).

Under certain market conditions, the Fund may invest in companies at the time of their initial public offering ("IPO").

Management process

The investment process for the All China strategy is driven by bottom-up proprietary research. As a starting point, the investment universe includes all investable quoted equities domiciled in China and/or of issuers generating the majority of their income in China. The investment team is expected to exclude companies exhibiting what we view as unsustainable business models, poor corporate governance practices, and negative industry dynamics. In order to form a qualitative assessment of a company, the Advisor scores companies based on a set of questions covering three areas:

1. Industry Structure and Company's Competitiveness

2. Trends & Profitability: Trends and Sustainability

3. Governance, disclosure, environmental and social practices

The Advisor further conducts extensive valuation analysis incorporating company/industry fundamentals, future operations, and cash generation. Peer comparisons and valuation bands are also studied based on historical and forward looking financials.

The Advisor seeks to construct a "best ideas," concentrated, high-conviction portfolio. The companies would be selected based on the attractiveness of their valuations, top down macro factors, and a conviction that the investment thesis is likely to be realized. Positions would be assigned weights based on the investment parameters for the strategy and the portfolio manager's conviction in the investment thesis. The Advisor aims to construct a portfolio diversified across many sectors with no single stock position being greater than 10% of the portfolio.

Risk [Heading]

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Main risks

Risk Narrative [Text Block]

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All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

China risk: There are special risks associated with investments in China, Hong Kong and Taiwan, including exposure to currency fluctuations, less liquidity, expropriation, confiscatory taxation, nationalization and exchange control regulations (including currency blockage). Inflation and rapid fluctuations in inflation and interest rates have had, and may continue to have, negative effects on the economy and securities markets of China, Hong Kong and Taiwan. In addition, investments in Taiwan could be adversely affected by its political and economic relationship with China. Certain securities issued by companies located or operating in China, such as China A-shares, are subject to trading restrictions, quota limitations and less market liquidity. Reduction in spending on Chinese products and services, institution of additional tariffs or other trade barriers, including as a result of heightened trade tensions between China and the United States, or a downturn in any of the economies of China's key trading partners may have an adverse impact on the Chinese economy.

Additionally, developing countries, such as China, may subject the Fund's investments to a number of tax rules, and the application of many of those rules may be uncertain. Changes in applicable Chinese tax law could reduce the after-tax profits of the Fund, directly or indirectly, including by reducing the after-tax profits of companies in China in which the Fund invests. Uncertainties in Chinese tax rules could result in unexpected tax liabilities for the Fund.

Foreign investing risk: The value of the Fund's investments in foreign securities may fall due to adverse political, social and economic developments abroad and due to decreases in foreign currency values relative to the US dollar. Investments in foreign government bonds involve special risks because the Fund may have limited legal recourse in the event of default. Also, foreign securities are sometimes less liquid and more difficult to sell and to value than securities of US issuers. These risks are greater for investments in emerging market issuers.

Emerging market risk: There are additional risks inherent in investing in less developed countries that are applicable to the Fund. Compared to the United States and other developed countries, investments in emerging market issuers may decline in value because of unfavorable foreign government actions, greater risks of political instability or the absence of accurate information about emerging market issuers. Further, emerging countries may have economies based on only a few industries and securities markets that trade only a small number of securities and employ settlement procedures different from those used in the United States. Prices on these exchanges tend to be volatile and, in the past, securities in these countries have offered greater potential for gain (as well as loss) than securities of companies located in developed countries. Further, investments by foreign investors are subject to a variety of restrictions in many emerging countries. Countries such as those in which the Fund may invest may experience high rates of inflation, high interest rates, exchange rate fluctuations or currency depreciation, large amounts of external debt, balance of payments and trade difficulties and extreme poverty and unemployment.

China A-shares risk: China A-shares are subject to a number of restrictions imposed by Chinese securities regulations and listing rules. Investments by foreign investors in A-shares are subject to various restrictions, regulations and limits. The A-share market is volatile with a risk of suspension of trading in a particular security or multiple securities or government intervention. The A-shares market can have a higher propensity for trading suspensions than many other global equity markets. Trading suspensions could lead to greater market execution risk, valuation risks, liquidity risks, and costs for the Fund.

Furthermore, any changes in laws, regulations and policies of the China A-shares market or rules in relation to Stock Connect may affect China A-share prices. These risks are heightened by the developing state of the PRC's investment and banking systems in general.

Per a circular (Caishui [2014] 79), the Fund is expected to be temporarily exempt from the Chinese withholding tax ("WHT") on capital gains on trading in A-shares. There is no indication as to how long the temporary exemption will remain in effect. Accordingly, the Fund may be subject to such taxes in the future. If the Fund expects such WHT on trading in A-shares to be imposed, it reserves the right to establish a reserve for such tax, although it currently does not do so. If the Fund establishes such a reserve but is not ultimately subject to the tax, shareholders who redeemed or sold their shares while the reserve was in place will effectively bear the tax and may not benefit from the later release, if any, of the reserve. Conversely, if the Fund does not establish such a reserve but ultimately is subject to the tax, shareholders who redeemed or sold their shares prior to the tax being withheld, reserved or paid will have effectively avoided the tax, even if they benefited from the trading that precipitated the Fund's payment of it. Investors should note that such provision may be excessive or inadequate to meet actual WHT liabilities (which could include interest and penalties) on the Fund's investments. As a result, investors may be advantaged or disadvantaged depending on the final rules of the relevant PRC tax authorities.

Stock Connect investing risk: Investing in A-shares through Stock Connect is subject to trading, clearance, settlement, and other procedures, which could pose risks to the Fund. Trading through the Stock Connect program is subject to daily quotas that limit the maximum daily net purchases on any particular day, each of which may restrict or preclude the Fund's ability to invest in A-shares through the Stock Connect program. A primary feature of the Stock Connect program is the application of the home market's laws and rules applicable to investors in A-shares. Therefore, the Fund's investments in Stock Connect A-shares are generally subject to PRC securities regulations and listing rules, among other restrictions. The Shanghai and Shenzhen markets may be open at a time when the Stock Connect Program is not trading, with the result that prices of China A-shares may fluctuate at times when the Fund is unable to add to or exit its position.

Offshore RMB risk: There is no assurance that there will always be sufficient amounts of RMB (i.e., Chinese currency) available for the Fund to remain fully invested in Chinese equities. The Chinese government heavily regulates the domestic exchange of foreign currencies and RMB exchange rates in China, which may adversely affect the operations and financial results of the Fund's investments in China.

Geographic concentration risk: The risk that if the Fund has most of its investments in a single country or region, its portfolio will be more susceptible to factors adversely affecting issuers located in that country or region than would a more geographically diverse portfolio of securities.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Small- and mid-capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the Fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments, and they may have more limited resources.

Non-diversification risk: The Fund is a non-diversified investment company, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company. As a non-diversified fund, the Fund's share price may be more volatile, and the Fund has a greater potential to realize losses upon the occurrence of adverse events affecting a particular issuer.

IPOs risk: The purchase of shares issued in IPOs may expose the Fund to the risks associated with issuers that have no operating history as public companies, as well as to the risks associated with the sectors of the market in which the issuer operates. The market for IPO shares may be volatile, and share prices of newly-public companies may fluctuate significantly over a short period of time.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market security. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in other funds risk: The Fund's investment performance is affected by the investment performance of the underlying funds in which the Fund may invest. Through its investment in the underlying funds, the Fund is subject to the risks of the underlying funds' investments and their expenses.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Real estate securities and REITs risk: The risk that the Fund's performance will be affected by adverse developments in the real estate industry. Real estate values may be affected by a variety of factors, including: local, national or global economic conditions; changes in zoning or other property-related laws; environmental regulations; interest rates; tax and insurance considerations; overbuilding; property taxes and operating expenses; or declining values in a neighborhood. Similarly, a REIT's performance depends on the types, values, locations and management of the properties it owns. In addition, a REIT may be more susceptible to adverse developments affecting a single project or market segment than a more diversified investment. Loss of status as a qualified REIT under the US federal tax laws could adversely affect the value of a particular REIT or the market for REITs as a whole.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose money by investing in the Fund.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The Fund is a non-diversified investment company, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company. As a non-diversified fund, the Fund's share price may be more volatile, and the Fund has a greater potential to realize losses upon the occurrence of adverse events affecting a particular issuer.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

There is no performance information quoted for the Fund as the Fund had not commenced investment operations as of the date of this prospectus.

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

There is no performance information quoted for the Fund as the Fund had not commenced investment operations as of the date of this prospectus.

Class P2 Prospectus | UBS All China Equity Fund | Class P2

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.85%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.60%

^[1]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.45%

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

1.15%

^[2]

Total annual fund operating expenses after management fee waiver/expense reimbursement

rr_NetExpensesOverAssets

0.30%

^[2]

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 31

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

$ 345

[1] "Other expenses" are based on estimates for the current fiscal year.

[2] The Trust, with respect to the Fund, and the Advisor, have entered into a written agreement pursuant to which the Advisor has agreed to waive its management fees and retained administration fees, and to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, extraordinary expenses and dividend expense and security loan fees for securities sold short) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, extraordinary expenses and dividend expense and security loan fees for securities sold short) through the period ending October 28, 2020 do not exceed 0.30%. Pursuant to the expense limitation agreement, the Advisor is entitled to be reimbursed for any expenses it reimburses to the extent such reimbursement can be made during the three years following the period during which such expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the reimbursement or (ii) at the time of the recoupment. The expense limitation agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the expense limitation agreement, however, the Advisor's three year recoupment rights will survive.

XML

Label

Element

Value

Class P2 Prospectus | UBS Sustainable Development Bank Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

UBS Sustainable Development Bank Bond Fund

Objective [Heading]

rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks current income.

Expense [Heading]

rr_ExpenseHeading

Fees and expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

These tables describe the fees and expenses that you may pay if you buy and hold shares of the Fund. Shares of Class P2 are available for purchase on behalf of clients of a fee-based program or certain other advisory programs in which UBS Asset Management (Americas) Inc., the Fund's investment advisor and administrator ("UBS AM (Americas)" or the "Advisor"), exercises investment discretion. Clients pay a wrap fee or a similar advisory fee to participate in such programs. Shares of Class P2 are also available for purchase on behalf of institutional clients with which the Advisor or its affiliates has signed a separate investment management agreement, pursuant to which such clients pay an advisory fee.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

Oct. 28, 2020

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. For the period October 24, 2018 (commencement of operations) through June 30, 2019, the Fund's portfolio turnover rate was 20%.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

20.00%

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

"Other expenses" are based on estimates for the current fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Principal investments

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in bonds and/or instruments that provide exposure to bonds issued by development banks. Development banks are financial organizations formed by government entities to promote economic and social development. The Fund invests in multilateral development bank bonds but may also invest in regional or national development bank obligations. The Fund's investment in obligations issued by the International Bank for Reconstruction and Development and the Inter-American Development Bank may be significant, but the Fund normally will not invest more than 25% of its net assets in either issuer.

Under normal circumstances, the Fund will invest in securities that, at the time of purchase, possess a minimum rating of A3 by Moody's Investors Service, Inc. ("Moody's") or A- by Standard & Poor's Financial Services LLC ("S&P") or Fitch Ratings, Inc. ("Fitch"), comparably rated by another nationally recognized statistical rating organization, or, if unrated, are determined by the Advisor to be of comparable quality.

The Fund's investments in fixed income securities may have all types of interest rate payment and reset terms. The Fund generally invests only in US dollar-denominated securities.

The Fund may, but is not required to, engage in derivatives transactions. Derivatives instruments such as futures may be used for risk management purposes to hedge against a specific security or for investment (non-hedging) purposes to earn income or adjust portfolio duration. The Fund does not seek to use derivatives extensively.

The Fund may invest in exchange-traded funds ("ETFs") to gain exposure to certain asset classes.

The Fund is a non-diversified fund, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company.

Management process

The Advisor seeks to invest in bonds issued by development banks. The Advisor constructs the portfolio consisting of multilateral and regional development banks. The Advisor focuses primarily on bonds issued by multilateral development banks which may include, but are not limited to, the International Bank for Reconstruction and Development and other member institutions of the World Bank Group, the Inter-American Development Bank, the Asian Development Bank, the African Development Bank, and the European Bank for Reconstruction and Development. Development banks are formed by their member states with the objective to provide financial and technical assistance to improve overall living standards through sustainable economic development and growth. While each development bank has a distinct focus, development banks generally use their capital for projects that seek to improve the state of the developing world, promote sustainable growth and raise living standards.

The Advisor selects investments for the Fund based on available supply and liquidity parameters (including, for example, such factors as evaluating amounts outstanding, available dealer inventory, and volumes traded in the secondary market) utilizing a stratified sampling approach (investing in a representative cross-section of the investment universe) to optimize tracking error and minimize transaction cost. The Fund will be managed relative to a composite index, which is a blend of two market indexes designed to measure the performance of the US dollar denominated multilateral development bank bond market. The Fund does not seek to directly replicate the index. The Fund's composite index is the Solactive UBS Global Multilateral Development Bank Bond USD 40% 1-5 Year 60% 5-10 Year Total Return Index. (The Fund reserves the right in its discretion to change the index). The Fund's development bank bond investments may include issuers that are not part of the composite index. The Fund will seek to maintain a concentrated portfolio of development bank bonds emphasizing multilateral development banks. The portfolio management team will select the bonds in the market that meet their selection criteria with intention to provide similar risk/return characteristics as the broader development bank bond market.

The Fund may engage in active trading to adjust the portfolio in response to investor activity and to rebalance the portfolio as new development bank issuers come to the market and existing issuers enter the index or mature.

Risk [Heading]

rr_RiskHeading

Main risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Below are some of the specific risks of investing in the Fund.

Risks of development bank bonds: The value of the Fund's investments in bonds issued by development banks may fall due to adverse financial market developments in the United States and abroad. Borrowers from development banks include foreign countries, which may include emerging market countries, and borrowers of specific development banks also include the private sector with or without government guarantee. Therefore, negative economic, social and political developments could affect the ability of a borrower to repay its loan to the development bank and thus affect its financial condition. In addition, investments in such development bank bonds may involve special risks because the Fund may have limited legal recourse in the event of default. Also, development bank bonds may sometimes be less liquid and more difficult to sell and to value than high-quality securities of US issuers. Bonds issued by a development bank are backed by the shareholders of the development bank. The development bank may be supported via various mechanisms including, preferred creditor status, equity injections by its shareholders and callable capital, even though the latter may have never been tested with respect to an issuer. Changes in the shareholder structure of a development bank or changes in the strength of the support by its shareholders could affect the credit rating and thus the value of the bonds issued by the development bank.

Concentration risk: The Fund concentrates in the bonds of development banks. The risk that if the Fund has most of its investments in a single industry, its portfolio will be more susceptible to factors adversely affecting that industry than would a more diverse portfolio of securities.

Interest rate risk: An increase in prevailing interest rates typically causes the value of fixed income securities to fall. Changes in interest rates will likely affect the value of longer-duration fixed income securities more than shorter-duration securities and higher quality securities more than lower quality securities. When interest rates are falling, some fixed income securities provide that the issuer may repay them earlier than the maturity date, and if this occurs the Fund may have to reinvest these repayments at lower interest rates. The Fund may face a heightened level of interest rate risk due to certain changes in monetary policy, such as certain types of interest rate changes by the Federal Reserve.

Credit risk: The risk that the Fund could lose money if the issuer or guarantor of a fixed income security, or the counterparty to or guarantor of a derivative contract, is unable or unwilling to meet its financial obligations. This risk is likely greater for lower quality investments than for investments that are higher quality.

Liquidity risk: The risk that investments cannot be readily sold at the desired time or price, and the Fund may have to accept a lower price or may not be able to sell the security at all. An inability to sell securities can adversely affect the Fund's value or prevent the Fund from taking advantage of other investment opportunities. Liquid portfolio investments may become illiquid or less liquid after purchase by the Fund due to low trading volume, adverse investor perceptions and/or other market developments. In recent years, the number and capacity of dealers that make markets in fixed income securities has decreased. Consequently, the decline in dealers engaging in market making trading activities may increase liquidity risk, which can be more pronounced in periods of market turmoil. Liquidity risk may be magnified in a rising interest rate environment or when investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. Liquidity risk includes the risk that the Fund will experience significant net redemptions at a time when it cannot find willing buyers for its portfolio securities or can only sell its portfolio securities at a material loss.

Non-diversification risk: The Fund is a non-diversified investment company, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company. As a non-diversified fund, the Fund's share price may be more volatile, and the Fund has a greater potential to realize losses upon the occurrence of adverse events affecting a particular issuer.

Portfolio turnover risk: High portfolio turnover from frequent trading will increase the Fund's transaction costs and may increase the portion of the Fund's capital gains that are realized for tax purposes in any given year. The Fund does not restrict the frequency of trading in order to limit expenses or the tax effect that its distributions may have on shareholders.

Market risk: The market value of the Fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole.

Leverage risk associated with financial instruments: The use of financial instruments to increase potential returns, including derivatives used for investment (non-hedging) purposes, may cause the Fund to be more volatile than if it had not been leveraged. The use of leverage may also accelerate the velocity of losses and can result in losses to the Fund that exceed the amount originally invested.

Derivatives risk: The value of "derivatives"—so called because their value "derives" from the value of an underlying asset, reference rate or index—may rise or fall more rapidly than other investments. It is possible for the Fund to lose more than the amount it invested in the derivative. The risks of investing in derivative instruments also include market risk, management risk, counterparty risk (which is the risk that a counterparty to a derivative contract is unable or unwilling to meet its financial obligations) and the risk that changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, index or overall market security. Derivatives relating to fixed income markets are especially susceptible to interest rate risk and credit risk. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments.

Investing in ETFs risk: The Fund's investment in ETFs may subject the Fund to additional risks than if the Fund would have invested directly in the ETF's underlying securities. These risks include the possibility that an ETF may experience a lack of liquidity that can result in greater volatility than its underlying securities; an ETF may trade at a premium or discount to its net asset value; an ETF may not replicate exactly the performance of the benchmark index it seeks to track; trading an ETF's shares may be halted if the listing exchange's officials deem such action appropriate; and a passively managed ETF would not necessarily sell a security because the issuer of the security was in financial trouble unless the security is removed from the index that the ETF seeks to track. In addition, investing in an ETF may also be more costly than if a Fund had owned the underlying securities directly. The Fund, and indirectly, shareholders of the Fund, bear a proportionate share of the ETF's expenses, which include management and advisory fees and other expenses. In addition, the Fund will pay brokerage commissions in connection with the purchase and sale of shares of the ETF.

Management risk: The risk that the investment strategies, techniques and risk analyses employed by the Advisor may not produce the desired results.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose money by investing in the Fund.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The Fund is a non-diversified investment company, which means that the Fund may invest more of its assets in a smaller number of issuers than a diversified investment company. As a non-diversified fund, the Fund's share price may be more volatile, and the Fund has a greater potential to realize losses upon the occurrence of adverse events affecting a particular issuer.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

There is no performance information quoted for the Fund as the Fund had not yet completed a full calendar year of operations as of the date of this prospectus.

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

There is no performance information quoted for the Fund as the Fund had not yet completed a full calendar year of operations as of the date of this prospectus.

Class P2 Prospectus | UBS Sustainable Development Bank Bond Fund | Class P2

Risk/Return:

rr_RiskReturnAbstract

Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.15%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

2.04%

^[1]

Total annual fund operating expenses

rr_ExpensesOverAssets

2.19%

Less management fee waiver/expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

2.04%

^[2]

Total annual fund operating expenses after management fee waiver/expense reimbursement

rr_NetExpensesOverAssets

0.15%

^[2]

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 15

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

488

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

987

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,363

[1] "Other expenses" are based on estimates for the current fiscal year. "Other expenses" include "Acquired fund fees and expenses," which were less than 0.01% of the average net assets of the Fund.

[2] The Trust, with respect to the Fund, and the Advisor, have entered into a written agreement pursuant to which the Advisor has agreed to waive its management fees and retained administration fees, and to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) to the extent necessary so that the Fund's ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) through the period ending October 28, 2020 do not exceed 0.15%. Pursuant to the expense limitation agreement, the Advisor is entitled to be reimbursed for any expenses it reimburses to the extent such reimbursement can be made during the three fiscal years following the period during which such expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the reimbursement or (ii) at the time of the recoupment. The expense limitation agreement may be terminated by the Fund's Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund's advisory contract with the Advisor. Upon termination of the expense limitation agreement, however, the Advisor's three year recoupment rights will survive.