485BPOS

Filed with the Securities and Exchange Commission on September 13, 2017

1933 Act Registration File No.   033-20827

1940 Act File No. 811- 05518

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933		[	X	]
Pre-Effective Amendment No.		[		]
Post-Effective Amendment No.	227	[	X	]

and/or

REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940		[	X	]
Amendment No.	229	[	X	]

(Check Appropriate Box or Boxes)

THE RBB FUND, INC.

(Exact Name of Registrant as Specified in Charter)

615 East Michigan Street,

Milwaukee, Wisconsin  53202

(Address of Principal Executive Offices, including Zip Code)

Registrant’s Telephone Number, including Area Code:  (302) 791-1851

Copies to:

SALVATORE FAIA	MICHAEL P. MALLOY, ESQUIRE
The RBB Fund, Inc.	Drinker Biddle & Reath LLP
615 East Michigan Street,	One Logan Square, Suite 2000
Milwaukee, Wisconsin  53202	Philadelphia, Pennsylvania 19103-6996

Approximate Date of Proposed Public Offering:  As soon as practicable after the Registration Statement becomes effective.

[	X	]	immediately upon filing pursuant to paragraph (b)
[		]	on (date) pursuant to paragraph (b)
[		]	60 days after filing pursuant to paragraph (a)(1)
[		]	on (date) pursuant to paragraph (a)(1)
[		]	75 days after filing pursuant to paragraph (a)(2)
[		]	on (date) pursuant to paragraph (a)(2) of Rule 485.

If appropriate, check the following box:

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

This Post-Effective Amendment (“PEA”) No. 227 to the Registration Statement for The RBB Fund, Inc. (the “Company”) on Form N-1A hereby incorporates Parts A, B and C from the Company’s PEA No. 226 on Form N-1A filed August 23, 2017.  This PEA No. 227 is filed for the sole purpose of submitting the XBRL exhibit for the risk/return summary first provided in PEA No. 226 to the Company’s Registration Statement.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended (the “1933 Act”), and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness of this Amendment to the Registration Statement under Rule 485(b) under the 1933 Act and that it has duly caused this  Amendment to the Registration Statement to be signed on its behalf by the undersigned, thereto duly authorized, in the City of Chadds Ford, and Commonwealth of Pennsylvania on September 13, 2017.

THE RBB FUND, INC.
By:	/s/ Salvatore Faia
	Salvatore Faia
	President

Pursuant to the requirements of the 1933 Act, this Amendment to Registrant’s Registration Statement has been signed below by the following persons in the capacities and on the date indicated.

SIGNATURE		TITLE	DATE
/s/ Salvatore Faia		President (Principal Executive Officer) and Chief Compliance Officer	September 13, 2017
Salvatore Faia
/s/ James G. Shaw		Treasurer (Chief Financial Officer) and Secretary	September 13, 2017
James G. Shaw
*J. Richard Carnall		Director	September 13, 2017
J. Richard Carnall
*Julian A. Brodsky		Director	September 13, 2017
Julian A. Brodsky
*Arnold M. Reichman		Director	September 13, 2017
Arnold M. Reichman
*Robert Sablowsky		Director	September 13, 2017
Robert Sablowsky
*Robert Straniere		Director	September 13, 2017
Robert Straniere
*Nicholas A. Giordano		Director	September 13, 2017
Nicholas A. Giordano
*Gregory P. Chandler		Director	September 13, 2017
Gregory P. Chandler
*Sam Lambroza		Director	September 13, 2017
Sam Lambroza
*By:	/s/ Salvatore Faia		September 13, 2017
Salvatore Faia Attorney-in-Fact

 

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Julian A. Brodsky, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw, Edward Paz, and Robert Amweg, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	February 16, 2017
	/s/ Julian A. Brodsky
	Julian A. Brodsky

2

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, J. Richard Carnall, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw, Edward Paz, and Robert Amweg, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	February 16, 2017
	/s/ J. Richard Carnall
	J. Richard Carnall

3

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Nicholas A. Giordano, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw, Edward Paz, and Robert Amweg, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	February 16, 2017
	/s/ Nicholas A. Giordano
	Nicholas A. Giordano

4

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Arnold M. Reichman, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw, Edward Paz, and Robert Amweg, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	February 16, 2017
	/s/ Arnold M. Reichman
	Arnold M. Reichman

5

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Robert Sablowsky, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw, Edward Paz, and Robert Amweg, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	February 16, 2017
	/s/ Robert Sablowsky
	Robert Sablowsky

6

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Robert A. Straniere, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw, Edward Paz, and Robert Amweg, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	February 16, 2017
	/s/ Robert Straniere
	Robert Straniere

7

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Gregory P. Chandler, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw, Edward Paz, and Robert Amweg, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	February 17, 2017
	/s/ Gregory P. Chandler
	Gregory P. Chandler

8

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Sam Lambroza, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw, Edward Paz, and Robert Amweg, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	February 16, 2017
	/s/ Sam Lambroza
	Sam Lambroza

9

INDEX TO EXHIBITS

Exhibit	Exhibit No.
Instance Document	EX-101.INS
Schema Document	EX-101.SCH
Calculation Linkbase Document	EX-101.CAL
Definition Linkbase Document	EX-101.DEF
Label Linkbase Document	EX-101.LAB
Presentation Linkbase Document	EX-101.PRE

10

XML

Boston Partners Emerging Markets Fund

SUMMARY SECTION — BOSTON PARTNERS EMERGING MARKETS FUND

Investment Objective

The Fund seeks long-term growth of capital.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy and hold Institutional Class shares of the Fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Boston Partners Emerging Markets Fund Institutional Class
Management fees	0.85%
Distribution and servicing (12b-1) fees	none
Other operating expenses	0.49%
Total annual Fund operating expenses	1.34%
Fee waiver and/or expense reimbursement	0.24%	[1]
Total annual Fund operating expenses after fee waiver and/or expense reimbursement	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 $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs of investing $100,000 in the Fund would be:

Expense Example	One Year	Three Years
Boston Partners Emerging Markets Fund | Institutional Class | USD ($)	1,121	4,009

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 Total annual Fund operating expenses or in the Example, affect the Fund's performance.

Summary of Principal Investment Strategies

The Fund will pursue its objective through a value oriented, research-driven strategy of investing in equity securities and financial instruments with equity like characteristics designed to provide exposure to emerging markets. Securities are selected by the Adviser using its "three circles" approach which combines a quantitative screening with a fundamental bottom up selection process. This investment strategy is grounded in the following principles: (1) low valuation stocks outperform high valuation stocks; (2) companies with strong fundamentals, e.g. high and sustainable returns on invested capital, outperform companies with weak fundamentals; and (3) stocks with positive business momentum, e.g. rising earnings estimates, outperform stocks with negative business momentum. The Adviser examines various factors in determining the value characteristics of issuers, including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals, such as return-on-equity and earnings growth and cash flow.

The Fund intends, under normal circumstances, to invest at least 80% of its net assets (including borrowings for investment purposes) in the securities of emerging market issuers, related derivative instruments and other investments that are tied economically to emerging market countries. The Adviser considers an emerging market country to include any country that is: 1) generally recognized to be an emerging market country by the international financial community, including the World Bank; 2) classified by the United Nations as a developing country; or 3) included in the MSCI Emerging Markets Index. Due to the unique relationship between China and its separately administered regions, the Adviser includes Hong Kong and Macau as emerging markets, independent of above definitions 1 through 3. The Adviser determines that an investment is tied economically to an emerging market if such investment satisfies one or more of the following conditions: 1) the issuer's primary trading market is in an emerging market; 2) the issuer is organized under the laws of, derives at least 50% of its revenue from, or has at least 50% of its assets in emerging markets; 3) the investment is included in an index representative of emerging markets; and 4) the investment is exposed to the economic risks and returns of emerging markets.

In managing the Fund's portfolio, the Adviser will seek to identify mispriced publicly traded equity securities of emerging market companies and purchase securities that the Adviser believes will outperform, emphasizing low valuation, positive business momentum and high quality.

The Fund's portfolio is rebalanced regularly to maintain the optimal risk/return trade-off. The Adviser assesses each stock's changing characteristics relative to its contribution to portfolio risk. The Adviser will sell a stock that the Adviser believes no longer offers an appropriate return-to-risk tradeoff. The Fund's investment adviser may engage in active trading, and will not consider portfolio turnover a limiting factor in making decisions for the Fund.

The equity securities in which the Fund will invest, which may include equity securities of non-U.S. issuers that are traded in the markets of the United States, include equity securities issued by large-, mid- and small- or micro-cap companies, as well as exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers").

The Fund may invest up to 20% of its net assets in high yield debt obligations (commonly known as "junk bonds"), such as bonds and debentures, used by corporations and other business organizations (e.g. trusts or limited liability companies). Such high yield debt obligations are not considered to be investment grade. Junk bonds are rated BB or lower by Standard & Poor's Rating Group, or have a comparable rating by another nationally recognized statistical rating organization (or, if unrated are determined by the Adviser to be of comparable quality at the time of investment). The Fund may invest in securities of the lowest rating category, including securities in default. The Adviser may, but is not required to, sell a bond or note held by the Fund in the event that its credit rating is downgraded. The Fund will primarily invest in fixed income instruments, including high yield debt obligations, when the Fund believes that such instruments offer a better risk/reward profile than comparable equity opportunites.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

In general, the Fund's investments will be spread over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry, except that the Fund may invest up to 30% in exchange-traded funds to the extent permitted by the Investment Company Act of 1940, as amended ("1940 Act"), and applicable SEC orders.

The Fund may participate as a purchaser in initial public offerings of securities ("IPOs"). An IPO is a company's first offering of stock to the public.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may also seek to increase its income by lending portfolio securities.

The Fund will invest in derivatives, including put and call options, futures, contracts for differences, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes. Contracts for differences offer exposure to price changes in an underlying security without ownership of such security, typically by providing investors the ability to trade on margin. The Fund's investments in derivative instruments may be leveraged and result in losses exceeding the amounts invested.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

• Limited Operating History Risk. The Fund has a limited operating history upon which prospective investors can evaluate its performance. Although the investment strategies described herein may have been utilized by investment accounts managed by the Adviser's investment team, past performance is not indicative of future results.

• New Fund Risk. As a new Fund, there can be no assurance that the Fund will grow to or maintain economically viable size.

• Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund makes may not perform as well as expected, and/or the Fund's portfolio management practices may not work to achieve their desired result.

• Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

• Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

• Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

• Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

• Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

• Micro-Cap Companies Risk. Micro-cap stocks may be very sensitive to changing economic conditions and market downturns because the issuers often have narrow markets for their products or services, fewer product lines, and more limited managerial and financial resources than larger issuers.  The stocks of micro-cap companies may therefore be more volatile and the ability to sell them at a desirable time or price may be more limited.

• Small-Cap Companies Risk. The stocks of smaller companies may be subject to more abrupt, erratic market movements than stocks of larger, more established companies.  Small companies may have limited product lines or financial resources, or may be dependent on a small or inexperienced management group, and their securities may trade less frequently and in lower volume than securities of larger companies, which could lead to higher transaction costs. Generally, the smaller the company size, the greater the risk.

• Mid-Cap Companies Risk. The stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies.

• Large-Cap Companies Risk. The stocks of large capitalization companies as a group could fall out of favor with the market, causing the Fund to underperform investments that focus solely on small- or medium-capitalization stocks.

• REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index. The Fund will indirectly bear its proportionate share of any expenses, including management fees, paid by an externally managed REIT in which it invests.

• Portfolio Turnover Risk. The Fund may frequently trade its portfolio securities, resulting in higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

• Segregated Account Risk. The Fund's transactions in derivative instruments may require the Fund to establish a segregated account consisting of cash or liquid securities in an amount sufficient to cover the transactions. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund's assets could impede portfolio management or the Fund's ability to meet redemption requests or other current obligations.

• Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

• Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

• Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations. Losses incurred by the Fund in writing options can be potentially unlimited.

• Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, contracts for differences, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

• IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

• Exchange Traded Fund Risk. Exchange traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in the duplication of expenses, including advisory fees, in addition to the Fund's own expenses.

• Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

• High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

• Equity Securities Risk. The Fund may invest in, or have exposure to, equity securities.  Equity securities tend to be more volatile than other investment choices, such as debt and money market instruments.  The value of your investment may decrease in response to overall stock market movements or the value of individual securities.

Performance Information

Performance for the Fund is not included because the Fund had not commenced operation prior to the date of this Prospectus. Updated performance information will be available online at www.bostonpartners.com or 1-888-261-4073.

[1] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Institutional Class shares exceeds 1.10% of the average daily net assets attributable to the Fund's Institutional Class shares. Because acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and/or expense reimbursements) are expected to exceed 1.10%. This contractual limitation is in effect until September 1, 2018 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.10% or the expense cap then in effect, whatever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

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485BPOS

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Aug. 23, 2017

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RBB FUND, INC.

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Aug. 23, 2017

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Aug. 23, 2017

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Sep. 01, 2017

Boston Partners Emerging Markets Fund

Risk Return Abstract

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Risk/Return [Heading]

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SUMMARY SECTION — BOSTON PARTNERS EMERGING MARKETS FUND

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Investment Objective

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The Fund seeks long-term growth of capital.

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Expenses and Fees

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This table describes the fees and expenses that you may pay if you buy and hold Institutional Class shares of the Fund.

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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

September 1, 2018

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 Total annual Fund operating expenses or in the Example, affect the Fund's performance.

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 $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs of investing $100,000 in the Fund would be:

Strategy [Heading]

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Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund will pursue its objective through a value oriented, research-driven strategy of investing in equity securities and financial instruments with equity like characteristics designed to provide exposure to emerging markets. Securities are selected by the Adviser using its "three circles" approach which combines a quantitative screening with a fundamental bottom up selection process. This investment strategy is grounded in the following principles: (1) low valuation stocks outperform high valuation stocks; (2) companies with strong fundamentals, e.g. high and sustainable returns on invested capital, outperform companies with weak fundamentals; and (3) stocks with positive business momentum, e.g. rising earnings estimates, outperform stocks with negative business momentum. The Adviser examines various factors in determining the value characteristics of issuers, including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals, such as return-on-equity and earnings growth and cash flow.

The Fund intends, under normal circumstances, to invest at least 80% of its net assets (including borrowings for investment purposes) in the securities of emerging market issuers, related derivative instruments and other investments that are tied economically to emerging market countries. The Adviser considers an emerging market country to include any country that is: 1) generally recognized to be an emerging market country by the international financial community, including the World Bank; 2) classified by the United Nations as a developing country; or 3) included in the MSCI Emerging Markets Index. Due to the unique relationship between China and its separately administered regions, the Adviser includes Hong Kong and Macau as emerging markets, independent of above definitions 1 through 3. The Adviser determines that an investment is tied economically to an emerging market if such investment satisfies one or more of the following conditions: 1) the issuer's primary trading market is in an emerging market; 2) the issuer is organized under the laws of, derives at least 50% of its revenue from, or has at least 50% of its assets in emerging markets; 3) the investment is included in an index representative of emerging markets; and 4) the investment is exposed to the economic risks and returns of emerging markets.

In managing the Fund's portfolio, the Adviser will seek to identify mispriced publicly traded equity securities of emerging market companies and purchase securities that the Adviser believes will outperform, emphasizing low valuation, positive business momentum and high quality.

The Fund's portfolio is rebalanced regularly to maintain the optimal risk/return trade-off. The Adviser assesses each stock's changing characteristics relative to its contribution to portfolio risk. The Adviser will sell a stock that the Adviser believes no longer offers an appropriate return-to-risk tradeoff. The Fund's investment adviser may engage in active trading, and will not consider portfolio turnover a limiting factor in making decisions for the Fund.

The equity securities in which the Fund will invest, which may include equity securities of non-U.S. issuers that are traded in the markets of the United States, include equity securities issued by large-, mid- and small- or micro-cap companies, as well as exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers").

The Fund may invest up to 20% of its net assets in high yield debt obligations (commonly known as "junk bonds"), such as bonds and debentures, used by corporations and other business organizations (e.g. trusts or limited liability companies). Such high yield debt obligations are not considered to be investment grade. Junk bonds are rated BB or lower by Standard & Poor's Rating Group, or have a comparable rating by another nationally recognized statistical rating organization (or, if unrated are determined by the Adviser to be of comparable quality at the time of investment). The Fund may invest in securities of the lowest rating category, including securities in default. The Adviser may, but is not required to, sell a bond or note held by the Fund in the event that its credit rating is downgraded. The Fund will primarily invest in fixed income instruments, including high yield debt obligations, when the Fund believes that such instruments offer a better risk/reward profile than comparable equity opportunites.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

In general, the Fund's investments will be spread over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry, except that the Fund may invest up to 30% in exchange-traded funds to the extent permitted by the Investment Company Act of 1940, as amended ("1940 Act"), and applicable SEC orders.

The Fund may participate as a purchaser in initial public offerings of securities ("IPOs"). An IPO is a company's first offering of stock to the public.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may also seek to increase its income by lending portfolio securities.

The Fund will invest in derivatives, including put and call options, futures, contracts for differences, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes. Contracts for differences offer exposure to price changes in an underlying security without ownership of such security, typically by providing investors the ability to trade on margin. The Fund's investments in derivative instruments may be leveraged and result in losses exceeding the amounts invested.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

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• Limited Operating History Risk. The Fund has a limited operating history upon which prospective investors can evaluate its performance. Although the investment strategies described herein may have been utilized by investment accounts managed by the Adviser's investment team, past performance is not indicative of future results.

• New Fund Risk. As a new Fund, there can be no assurance that the Fund will grow to or maintain economically viable size.

• Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund makes may not perform as well as expected, and/or the Fund's portfolio management practices may not work to achieve their desired result.

• Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

• Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

• Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

• Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

• Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

• Micro-Cap Companies Risk. Micro-cap stocks may be very sensitive to changing economic conditions and market downturns because the issuers often have narrow markets for their products or services, fewer product lines, and more limited managerial and financial resources than larger issuers.  The stocks of micro-cap companies may therefore be more volatile and the ability to sell them at a desirable time or price may be more limited.

• Small-Cap Companies Risk. The stocks of smaller companies may be subject to more abrupt, erratic market movements than stocks of larger, more established companies.  Small companies may have limited product lines or financial resources, or may be dependent on a small or inexperienced management group, and their securities may trade less frequently and in lower volume than securities of larger companies, which could lead to higher transaction costs. Generally, the smaller the company size, the greater the risk.

• Mid-Cap Companies Risk. The stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies.

• Large-Cap Companies Risk. The stocks of large capitalization companies as a group could fall out of favor with the market, causing the Fund to underperform investments that focus solely on small- or medium-capitalization stocks.

• REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index. The Fund will indirectly bear its proportionate share of any expenses, including management fees, paid by an externally managed REIT in which it invests.

• Portfolio Turnover Risk. The Fund may frequently trade its portfolio securities, resulting in higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

• Segregated Account Risk. The Fund's transactions in derivative instruments may require the Fund to establish a segregated account consisting of cash or liquid securities in an amount sufficient to cover the transactions. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund's assets could impede portfolio management or the Fund's ability to meet redemption requests or other current obligations.

• Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

• Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

• Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations. Losses incurred by the Fund in writing options can be potentially unlimited.

• Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, contracts for differences, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

• IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

• Exchange Traded Fund Risk. Exchange traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in the duplication of expenses, including advisory fees, in addition to the Fund's own expenses.

• Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

• High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

• Equity Securities Risk. The Fund may invest in, or have exposure to, equity securities.  Equity securities tend to be more volatile than other investment choices, such as debt and money market instruments.  The value of your investment may decrease in response to overall stock market movements or the value of individual securities.

Risk Lose Money [Text]

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Investors may lose money.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance One Year or Less [Text]

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Performance for the Fund is not included because the Fund had not commenced operation prior to the date of this Prospectus.

Performance Availability Phone [Text]

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1-888-261-4073

Performance Availability Website Address [Text]

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www.bostonpartners.com

Performance Table Closing [Text Block]

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Performance for the Fund is not included because the Fund had not commenced operation prior to the date of this Prospectus. Updated performance information will be available online at www.bostonpartners.com or 1-888-261-4073.

Boston Partners Emerging Markets Fund | Institutional Class

Risk Return Abstract

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Management fees

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0.85%

Distribution and servicing (12b-1) fees

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none

Other operating expenses

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0.49%

Total annual Fund operating expenses

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1.34%

Fee waiver and/or expense reimbursement

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(0.24%)

^[1]

Total annual Fund operating expenses after fee waiver and/or expense reimbursement

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1.10%

One Year

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$ 1,121

Three Years

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$ 4,009

[1] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Institutional Class shares exceeds 1.10% of the average daily net assets attributable to the Fund's Institutional Class shares. Because acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and/or expense reimbursements) are expected to exceed 1.10%. This contractual limitation is in effect until September 1, 2018 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.10% or the expense cap then in effect, whatever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.