Loomis Sayles Intermediate Municipal Bond Fund


	Summary Prospectus May 1, 2021, as revised September 30, 2021

Ticker Symbol: Class A (MIMAX), Class C (MIMCX), Class T* (MIMTX) and Class Y (MIMYX)

*	Class T shares of the Fund are not currently available for purchase.

Before you invest, you may want to review the Fund’s Prospectus, which contains more information about the Fund and its risks. You can find the Fund’s Prospectus, reports to shareholders, and other information about the Fund online at im.natixis.com/fund-documents. You can also get this information at no cost by calling 800-225-5478 or by sending an e-mail request to NatixisFunds@natixis.com. The Fund’s Prospectus and Statement of Additional Information, each dated May 1, 2021, as may be revised or supplemented from time to time, are incorporated by reference into this Summary Prospectus.

Investment Goal

The Fund seeks a high level of federal tax-exempt current income, consistent with the preservation of capital.

Fund Fees & Expenses

The following table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in the Natixis Funds Complex. More information about these and other discounts is available from your financial professional and in the section “How Sales Charges Are Calculated” on page 75 of the Prospectus, in Appendix A to the Prospectus and on page 136 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).

Shareholder Fees


(fees paid directly from your investment)	Class A	Class C	Class T	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	3.00%	None	2.50%	None
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	None*	1.00%	None	None
Redemption fees	None	None	None	None

*	A 0.75% contingent deferred sales charge (“CDSC”) may apply to certain purchases of Class A shares of $500,000 or more that are redeemed within eighteen months of the date of purchase.

Annual Fund Operating Expenses


(expenses that you pay each year as a percentage of the value of your investment)	Class A	Class C	Class T	Class Y
Management fees	0.40%	0.40%	0.40%	0.40%
Distribution and/or service (12b-1) fees	0.25%	1.00%	0.25%	0.00%
Other expenses¹	0.78%	0.78%	0.78%²	0.77%
Total annual fund operating expenses	1.43%	2.18%	1.43%	1.17%
Fee waiver and/or expense reimbursement³	0.72%	0.72%	0.72%	0.71%
Total annual fund operating expenses after fee waiver and/or expense reimbursement	0.71%	1.46%	0.71%	0.46%

The expense information shown in the table above includes acquired fund fees and expenses of less than 0.01%; the ratios differ from the expense information disclosed in the Fund’s financial highlights table because the financial highlights table reflects the operating expenses of the Fund and does not include acquired fund fees and expenses.

2	Other expenses for Class T shares are estimated for the current fiscal year.

The Fund’s investment adviser has given a binding contractual undertaking to the Fund to limit the amount of the Fund’s total annual fund operating expenses to 0.70%, 1.45%, 0.70% and 0.45% of the Fund’s average daily net assets for Class A, Class C, Class T and Class Y shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through April 30, 2022 and may be terminated before then only with the consent of the Fund’s Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below the applicable expense limitations for Class A, Class C, Class T and Class Y shares. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

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 redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same, except that the example is

Fund Summary

based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement assuming that such waiver and/or reimbursement will only be in place through the date noted above and on the Total Annual Fund Operating Expenses for the remaining periods. The example for Class C shares for the ten-year period reflects the conversion to Class A shares after eight years. The example does not take into account brokerage commissions and other fees to financial intermediaries that you may pay on your purchases and sales of shares of the Fund. Although your actual costs may be higher or lower, based on these assumptions your costs would be:


If shares are redeemed:	1 year		3 years		5 years		10 years
Class A	$	370	$	670	$	992	$	1,901
Class C	$	249	$	613	$	1,104	$	2,266
Class T	$	321	$	622	$	945	$	1,860
Class Y	$	47	$	301	$	575	$	1,357


If shares are not redeemed:	1 year		3 years		5 years		10 years
Class C	$	149	$	613	$	1,104	$	2,266

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 for you if your 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 its most recently ended fiscal year, the Fund’s portfolio turnover rate was 41% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

Under normal market conditions, the Fund will invest at least 80% of its net assets (plus borrowings made for investment purposes) in municipal securities that pay interest exempt from federal income taxes. Municipal securities are debt instruments typically issued by or on behalf of state and local governments, territories or possessions of the United States, including the District of Columbia, and their political subdivisions, agencies and instrumentalities and may include general obligation, revenue and private activity bonds and notes. In addition, the Fund may invest up to 20% of its assets in securities that pay interest subject to federal income taxation. The Fund may invest up to 20% of its assets in debt securities subject to the federal alternative minimum tax. The Fund’s investments may include securities issued by the U.S. government, its agencies and instrumentalities and corporate debt securities. The Fund will invest primarily in investment grade fixed-income securities. “Investment grade” securities are those securities that are rated in one of the top four ratings categories at the time of purchase by at least one of the three major ratings agencies (Moody’s Investors Service, Inc., Fitch Investors Services, Inc. or S&P Global Ratings), or, if unrated, are determined by Loomis, Sayles & Company, L.P. (“Loomis Sayles” or the “Subadviser”) to be of comparable quality. The Subadviser considers pre-refunded bonds and municipal securities escrowed to maturity using U.S. Treasury securities or U.S. government agency securities to be investment grade securities, regardless of rating. The Fund may also invest up to 10% of its assets in securities that are not investment grade (commonly known as “junk bonds”). Under normal circumstances, the dollar-weighted average effective maturity of the Fund’s portfolio is expected to be between 3 and 10 years although the Fund may invest in securities of any maturity.

The portfolio management team seeks to build a portfolio based on a number of factors including sector, duration and maturity distribution, yield, expected return, credit momentum outlook (sector and security level), credit quality, security structure, issue size and liquidity. Through the use of quantitative and fundamental analysis, the pool of possible portfolio investments is screened using these factors to arrive at a narrower universe of securities that the Subadviser believes are suitable for the Fund’s portfolio.

Potential investments are also subject to a portfolio risk assessment that may include the following:

•	Determining the ability of creditors to fully repay debt obligations in a timely manner.

•	Use of a wide variety of internal and external quantitative and analytical and informational sources to assess likelihood of repayment.

•	Monitoring rating agency and third party surveillance sources with an emphasis on core holdings.

The Subadviser may sell a security for a variety of reasons, including duration management, yield curve positioning, sector rotation, a change in credit momentum outlook or if more attractive investment opportunities are identified.

The Fund may also:

•	Invest in when-issued securities and securities issued pursuant to Rule 144A under the Securities Act of 1933 (“Rule 144A securities”).

•	Enter into futures transactions for hedging and investment purposes.

•	Invest in other investment companies to the extent permitted by the Investment Company Act of 1940.

Fund Summary

Principal Investment Risks

The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund.

The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund’s portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund.

Market/Issuer Risk: The market value of the Fund’s investments will move up and down, sometimes rapidly and unpredictably, based upon overall market and economic conditions, as well as a number of reasons that directly relate to the issuers of the Fund’s investments, such as management performance, financial condition and demand for the issuers’ goods and services.

Interest Rate Risk: Interest rate risk is the risk that the value of the Fund’s investments will fall if interest rates rise. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. Interest rate risk generally is greater for funds that invest in fixed-income securities with relatively longer durations than for funds that invest in fixed-income securities with shorter durations. In addition, an economic downturn or period of rising interest rates could adversely affect the market for these securities and reduce the Fund’s ability to sell them, negatively impacting the performance of the Fund. Potential future changes in government monetary policy may affect the level of interest rates.

Management Risk: A strategy used by the Fund’s portfolio managers may fail to produce the intended result.

Liquidity Risk: Liquidity risk is the risk that the Fund may be unable to find a buyer for its investments when it seeks to sell them or to receive the price it expects. Decreases in the number of financial institutions willing to make markets in the Fund’s investments or in their capacity or willingness to transact may increase the Fund’s exposure to this risk. Events that may lead to increased redemptions, such as market disruptions or increases in interest rates, may also negatively impact the liquidity of the Fund’s investments when it needs to dispose of them. If the Fund is forced to sell its investments at an unfavorable time and/or under adverse conditions in order to meet redemption requests, such sales could negatively affect the Fund. Securities acquired in a private placement, such as Rule 144A securities, are generally subject to significant liquidity risk because they are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Derivatives, and particularly over-the-counter (“OTC”) derivatives, are generally subject to liquidity risk as well. Liquidity issues may also make it difficult to value the Fund’s investments.

Investments in Other Investment Companies Risk: The Fund will indirectly bear the management, service and other fees of any other investment companies, including exchange-traded funds, in which it invests in addition to its own expenses.

Below Investment Grade Fixed-Income Securities Risk: The Fund’s investments in below investment grade fixed-income securities, also known as “junk bonds,” may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit/counterparty risk (including a greater risk of default) and liquidity risk. The ability of the issuer to make principal and interest payments is predominantly speculative for below investment grade fixed-income securities.

Credit/Counterparty Risk: Credit/counterparty risk is the risk that the issuer or guarantor of a fixed-income security, or the counterparty to a derivatives or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations. As a result, the Fund may sustain losses or be unable or delayed in its ability to realize gains.The Fund will be subject to credit/counterparty risk with respect to the counterparties to its derivatives transactions. This risk will be heightened to the extent the Fund enters into derivative transactions with a single counterparty (or affiliated counterparties that are part of the same organization), causing the Fund to have significant exposure to such counterparty. Many of the protections afforded to participants on organized exchanges and clearing houses, such as the performance guarantee given by a central clearing house, are not available in connection with over-the-counter (“OTC”) derivatives transactions. For centrally cleared derivatives, such as futures, the primary credit/counterparty risk is the creditworthiness of the Fund’s clearing broker and the central clearing house itself.

Cybersecurity and Technology Risk: The Fund, its service providers, and other market participants increasingly depend on complex information technology and communications systems, which are subject to a number of different threats and risks that could adversely affect the Fund and its shareholders. Cybersecurity and other operational and technology issues may result in financial losses to the Fund and its shareholders.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including futures transactions) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those that would have occurred had derivatives not been used. The Fund’s use of derivatives, such as futures transactions, involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than the initial margin (if any) required to initiate derivatives positions. There is also the risk that the Fund may be unable to terminate or sell a derivatives position at an advantageous time or price. The Fund’s derivative counterparties may experience financial difficulties or otherwise be unwilling or unable to honor their obligations, possibly resulting in losses to the Fund.

Fund Summary

Large Investor Risk: Ownership of shares of the Fund may be concentrated in one or a few large investors. Such investors may redeem shares in large quantities or on a frequent basis. Redemptions by a large investor can affect the performance of the Fund, may increase realized capital gains, including short-term capital gains taxable as ordinary income, may accelerate the realization of taxable income to shareholders and may increase transaction costs. These transactions potentially limit the use of any capital loss carryforwards and certain other losses to offset future realized capital gains (if any). Such transactions may also increase the Fund’s expenses.

Municipal Securities Risk: Municipal bonds are investments issued by states, cities, public authorities or political subdivisions to raise money for public purposes, including general obligation bonds and revenue obligations. Municipal securities are subject to information risk, liquidity risk, credit risk and the risks that economic, political, fiscal or regulatory events, legislative changes and the enforceability of rights of municipal bond holders could adversely affect the values of municipal bonds. Municipal obligations may be susceptible to downgrades or defaults during recessions or similar periods of economic stress and insolvent municipalities may file for bankruptcy, which could significantly affect the rights of creditors and the value of the municipal securities. In addition, if the municipal securities held by the Fund fail to meet certain legal requirements allowing interest distributed from such securities to be tax-exempt, the interest received and distributed to shareholders by the Fund may be taxable.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide 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 returns for the one-year, five-year and life-of-fund periods (as applicable) compare to those of a broad measure of market performance. Class C shares will automatically convert to Class A shares after eight years. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at im.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.

Total Returns for Class Y Shares


	Highest Quarterly Return: First Quarter 2019, 2.66% Lowest Quarterly Return: Fourth Quarter 2016, -3.76%


Average Annual Total Returns
(for the periods ended December 31, 2020)	Past 1 Year	Past 5 Years	Life of Fund (12/31/12)
Class Y - Return Before Taxes	3.63%	3.08%	2.74%
Return After Taxes on Distributions	3.63%	3.08%	2.74%
Return After Taxes on Distributions and Sale of Fund Shares	2.99%	2.87%	2.55%
Class A - Return Before Taxes	0.38%	2.21%	2.06%
Class C - Return Before Taxes	1.71%	2.06%	1.70%
Class T - Return Before Taxes	0.85%	2.31%	2.14%
Bloomberg Barclays Municipal Bond Index	5.21%	3.91%	3.61%

The Fund did not have Class T shares outstanding during the periods shown above. The returns of Class T shares would have been substantially similar to the returns of the Fund’s other share classes because they would have been invested in the same portfolio of securities and would only differ to the extent the other share classes did not have the same expenses. Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T shares.

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. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual

Fund Summary

retirement accounts. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.

Management

Investment Adviser

Natixis Advisors, LLC (“Natixis Advisors”)

Investment Subadviser

Loomis, Sayles & Company, L.P. (“Loomis Sayles”)

Portfolio Managers

Pramila Agrawal, CFA^®, Ph.D., Vice President of Loomis Sayles, has served as co-portfolio manager of the Fund since 2021.

James LeBuhn, Vice President of Loomis Sayles, has served as co-portfolio manager of the Fund since 2021.

Dawn Mangerson, Vice President of Loomis Sayles, has served as co-portfolio manager of the Fund since 2012.

Purchase and Sale of Fund Shares

Class A and C Shares

The following chart shows the investment minimums for various types of accounts:


Type of Account	Minimum Initial Purchase		Minimum Subsequent Purchase
Any account other than those listed below	$	2,500	$	50
For shareholders participating in Natixis Funds’ Investment Builder Program	$	1,000	$	50
For Traditional IRA, Roth IRA, Rollover IRA, SEP-IRA and Keogh plans using the Natixis Funds’ prototype document (direct accounts, not held through intermediary)	$	1,000	$	50
Coverdell Education Savings Accounts using the Natixis Funds’ prototype document (direct accounts, not held through intermediary)	$	500	$	50

There is no initial or subsequent investment minimum for:

•	Fee Based Programs (such as wrap accounts) where an advisory fee is paid to the broker-dealer or other financial intermediary. Please consult your financial representative to determine if your fee based program is subject to additional or different conditions or fees.

•	Certain Retirement Plans. Please consult your retirement plan administrator to determine if your retirement plan is subject to additional or different conditions or fees imposed by the plan administrator.

•	Clients of a Registered Investment Adviser where the Registered Investment Adviser receives an advisory, management or consulting fee.

The minimum investment requirements for Class A shares may be waived or lowered for investments effected through certain financial intermediaries that have entered into special arrangements with Natixis Distribution, LLC (the “Distributor”). Consult your financial intermediary for additional information regarding the minimum investment requirement applicable to your investment.

Class T Shares

Class T shares of the Fund are not currently available for purchase.

Class T shares of the Fund may only be purchased by investors who are investing through an authorized third party, such as a broker-dealer or other financial intermediary, that has entered into a selling agreement with the Distributor. Investors may not hold Class T shares directly with the Fund. Class T shares are subject to a minimum initial investment of $2,500 and a minimum subsequent investment of $50. Not all financial intermediaries make Class T shares available to their clients.

Class Y Shares

Class Y shares of the Fund are generally subject to a minimum initial investment of $100,000 and a minimum subsequent investment of $50, except there is no minimum initial or subsequent investment for:

•	Fee Based Programs (such as wrap accounts) where an advisory fee is paid to the broker-dealer or other financial intermediary. Please consult your financial representative to determine if your fee based program is subject to additional or different conditions or fees.

•	Certain Retirement Plans. Please consult your retirement plan administrator to determine if your retirement plan is subject to additional or different conditions or fees imposed by the plan administrator.

•	Certain Individual Retirement Accounts if the amounts invested represent rollover distributions from investments by any of the retirement plans invested in the Fund.

Fund Summary

•	Clients of a Registered Investment Adviser where the Registered Investment Adviser receives an advisory, management or consulting fee.

•

Fund Trustees, former Fund trustees, employees of affiliates of the Natixis Funds and other individuals who are affiliated with any Natixis Fund (this also applies to any spouse, parents, children, siblings, grandparents, grandchildren and in-laws of those mentioned) and Natixis affiliate employee benefit plans.

At the discretion of Natixis Advisors, LLC, clients of Natixis Advisors, LLC and its affiliates may purchase Class Y shares of the Fund below the stated minimums.

Due to operational limitations at your financial intermediary, certain fee based programs, retirement plans, individual retirement accounts and accounts of registered investment advisers may be subject to the investment minimums described above.

The Fund’s shares are available for purchase and are redeemable on any business day through your investment dealer, directly from the Fund by writing to the Fund at Natixis Funds, P.O. Box 219579, Kansas City, MO 64121-9579, by exchange, by wire, by internet at im.natixis.com (certain restrictions may apply), through the Automated Clearing House system, or, in the case of redemptions, by telephone at 800-225-5478 or by the Systematic Withdrawal Plan.

Tax Information

The Fund intends to distribute exempt-interest dividends, which are exempt from federal income tax. A portion of the Fund’s exempt-interest dividends may be subject to the federal alternative minimum tax. Also, a portion of the Fund’s distributions may not qualify as exempt-interest dividends; rather, such portion will generally be taxable to you as ordinary income or capital gains, except for distributions to retirement plans and other investors that qualify for tax-exempt treatment under U.S. federal income tax law generally. Investments in such tax-advantaged plans will generally be taxed only upon withdrawal of monies from the tax-exempt arrangement.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase shares of the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies may pay the intermediary for the sale of the Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary’s website for more information.

UMIMB77-0921