PIMCO National Intermediate Municipal
Bond Fund

SUMMARY PROSPECTUS

JULY 31, 2015 (as supplemented June 1, 2016)

Share Class:	Inst	P	Admin	D	A	C	R
Ticker:	PMNIX	PMNPX	PMNQX	PMNDX	PMNTX	PMNNX	PMNRX

Before you invest, you may want to review the Fund's prospectus, which, as supplemented, contains more information about the Fund and its risks. You can find the Fund's prospectus and other information about the Fund online at http://investments.pimco.com/prospectuses. You can also get this information at no cost by calling 888.87.PIMCO or by sending an email request to pimcoteam@bfdsmidwest.com. The Fund's prospectus and Statement of Additional Information, both dated July 31, 2015, as supplemented, along with the financial statements included in the Fund's most recent annual report to shareholders dated March 31, 2015, are incorporated by reference into this Summary Prospectus.

Investment Objective

The Fund seeks maximum tax exempt income.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. 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 Class A shares of eligible funds offered by PIMCO Equity Series and PIMCO Funds. More information about these and other discounts is available in the "Classes of Shares" section on page 52 of the Fund's prospectus or from your financial advisor.

Shareholder Fees (fees paid directly from your investment):

	Inst Class	Class P	Admin Class	Class D	Class A	Class C	Class R
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	None	None	None	None	2.25%	None	None
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original purchase price or redemption price)	None	None	None	None	1.00%	1.00%	None

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

	Inst Class	Class P	Admin Class	Class D	Class A	Class C	Class R
Management Fees	0.45%	0.55%	0.45%	0.55%	0.55%	0.55%	0.55%
Distribution and/or Service (12b-1) Fees	N/A	N/A	0.25%	0.25%	0.25%	0.75%	0.50%
Total Annual Fund Operating Expenses	0.45%	0.55%	0.70%	0.80%	0.80%	1.30%	1.05%

Example . The Example is intended to help you compare the cost of investing in Institutional Class, Class P, Administrative Class, Class D, Class A, Class C or Class R shares of the Fund with the costs of investing in other mutual funds. The Example assumes that you invest $10,000 in the noted class of shares for the time periods indicated and then redeem all your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If you redeem your shares at the end of each period:

	1 Year	3 Years	5 Years	10 Years
Institutional Class	$46	$144	$252	$567
Class P	$56	$176	$307	$689
Administrative Class	$72	$224	$390	$871
Class D	$82	$255	$444	$990
Class A	$305	$475	$659	$1,193
Class C	$232	$412	$713	$1,568
Class R	$107	$334	$579	$1,283

If you do not redeem your shares:

	1 Year	3 Years	5 Years	10 Years
Institutional Class	$46	$144	$252	$567
Class P	$56	$176	$307	$689
Administrative Class	$72	$224	$390	$871
Class D	$82	$255	$444	$990
Class A	$305	$475	$659	$1,193
Class C	$132	$412	$713	$1,568
Class R	$107	$334	$579	$1,283

Portfolio Turnover

The Fund pays transaction costs 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 the Annual Fund Operating Expenses or in the Example tables, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 25% of the average value of its portfolio.

Principal Investment Strategies

The Fund seeks to achieve its investment objective by investing under normal circumstances at least 80% of its assets in debt securities whose interest is, in the opinion of bond counsel for the issuer at the time of issuance, exempt from federal income tax ("Municipal Bonds"). Municipal Bonds generally are issued by or on behalf of states and local governments and their agencies, authorities and other instrumentalities.

The Fund may invest in Fixed Income Instruments which include bonds, debt securities and other similar instruments issued by various U.S. and non-U.S. public- or private-sector entities. The Fund may invest without limitation in "private activity" bonds whose interest is a tax-preference item for purposes of the federal alternative minimum tax ("AMT"). For shareholders subject to the AMT, distributions derived from "private activity" bonds must be included in their AMT calculations, and as such a portion of the Fund's distribution may be subject to federal income tax. The Fund is non- diversified, which means that it may invest its assets in a smaller number of issuers than a diversified fund. The Fund may invest more than 25% of its

PIMCO FUNDS | SUMMARY PROSPECTUS

PIMCO National Intermediate Municipal
Bond Fund

total assets in bonds of issuers in California and New York. To the extent that the Fund concentrates its investments in California or New York, it will be subject to California or New York State-Specific Risk. The Fund may also invest 25% or more of its total assets in Municipal Bonds that finance education, health care, housing, transportation, utilities and other similar projects, and 25% or more of its total assets in industrial development bonds. The Fund may invest the remainder of its net assets in other types of Fixed Income Instruments. "Fixed Income Instruments" include bonds, debt securities and other similar instruments issued by various U.S. and non-U.S. public- or private-sector entities. The average portfolio duration of this Fund normally varies within (negative) 2 years to positive 4 years of the portfolio duration of the securities comprising the Barclays 1-15 Year Municipal Bond Index, as calculated by Pacific Investment Management Company LLC ("PIMCO"), which as of June 30, 2015 was 5.11 years. Duration is a measure used to determine the sensitivity of a security's price to changes in interest rates. The longer a security's duration, the more sensitive it will be to changes in interest rates. The portfolio manager focuses on bonds with the potential to offer attractive current income, typically looking for bonds that can provide consistently attractive current yields or that are trading at competitive market prices. Capital appreciation, if any, generally arises from decreases in interest rates or improving credit fundamentals for a particular state, municipality or issuer.

The Fund invests primarily in investment grade debt securities, but may invest up to 10% of its total assets in Municipal Bonds or "private activity" bonds which are high yield securities ("junk bonds") rated at least Ba by Moody's Investors Service, Inc. ("Moody's"), or equivalently rated by Standard & Poor's Ratings Services ("S&P") or Fitch, Inc. ("Fitch"), or, if unrated, determined by PIMCO to be of comparable quality.

The Fund may invest in derivative instruments, such as options, futures contracts or swap agreements, and invest in mortgage- or asset-backed securities. The Fund may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis and may engage in short sales. The Fund may also invest in securities issued by entities, such as trusts, whose underlying assets are Municipal Bonds, including, without limitation, residual interest bonds. The Fund may, without limitation, seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as buy backs or dollar rolls). The Fund may also invest up to 10% of its total assets in preferred stocks.

Principal Risks

It is possible to lose money on an investment in the Fund. The principal risks of investing in the Fund, which could adversely affect its net asset value, yield and total return are:

New/Small Fund Risk: the risk that a new or smaller Fund's performance may not represent how the Fund is expected to or may perform in the long-term. In addition, new Funds have limited operating histories for investors to evaluate and new and smaller Funds may not attract sufficient assets to achieve investment and trading efficiencies

Interest Rate Risk: the risk that fixed income securities will decline in value because of an increase in interest rates; a fund with a longer average portfolio duration will be more sensitive to changes in interest rates than a fund with a shorter average portfolio duration

Call Risk: the risk that an issuer may exercise its right to redeem a fixed income security earlier than expected (a call). Issuers may call outstanding securities prior to their maturity for a number of reasons (e.g., declining interest rates, changes in credit spreads and improvements in the issuer's credit quality). If an issuer calls a security that the Fund has invested in, the Fund may not recoup the full amount of its initial investment and may be forced to reinvest in lower-yielding securities, securities with greater credit risks or securities with other, less favorable features

Credit Risk: the risk that the Fund could lose money if the issuer or guarantor of a fixed income security, or the counterparty to a derivative contract, is unable or unwilling to meet its financial obligations

High Yield Risk: the risk that high yield securities and unrated securities of similar credit quality (commonly known as "junk bonds") are subject to greater levels of credit, call and liquidity risks. High yield securities are considered primarily speculative with respect to the issuer's continuing ability to make principal and interest payments, and may be more volatile than higher-rated securities of similar maturity

Market Risk: the risk that the value of securities owned by the Fund may go up or down, sometimes rapidly or unpredictably, due to factors affecting securities markets generally or particular industries

Issuer Risk: the risk that the value of a security may decline for a reason directly related to the issuer, such as management performance, financial leverage and reduced demand for the issuer's goods or services

Liquidity Risk: the risk that a particular investment may be difficult to purchase or sell and that the Fund may be unable to sell illiquid securities at an advantageous time or price or achieve its desired level of exposure to a certain sector. Liquidity risk may result from the lack of an active market, reduced number and capacity of traditional market participants to make a market in fixed income securities, and may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed income mutual funds may be higher than normal, causing increased supply in the market due to selling activity

Derivatives Risk: the risk of investing in derivative instruments (such as futures, swaps and structured securities), including liquidity, interest rate, market, credit and management risks, mispricing or valuation complexity. Changes in the value of the derivative may not correlate perfectly with, and may be more sensitive to market events than, the underlying asset, rate or index, and the Fund could lose more than the initial amount invested. The Fund's use of derivatives may result in losses to the Fund, a reduction in the Fund's returns and/or increased volatility. Over-the-counter derivatives are also subject to the risk that the other party in the transaction will not fulfill its contractual obligations. For derivatives traded on exchanges, the primary credit risk is the creditworthiness of the Fund's clearing broker or the exchange itself

Equity Risk: the risk that the value of equity securities, such as common stocks and preferred stocks, may decline due to general market conditions which are not specifically related to a particular company or to factors

2      SUMMARY PROSPECTUS | PIMCO FUNDS     

Summary Prospectus

affecting a particular industry or industries. Equity securities generally have greater price volatility than fixed income securities

Mortgage-Related and Other Asset-Backed Securities Risk: the risks of investing in mortgage-related and other asset-backed securities, including interest rate risk, extension risk, prepayment risk, and credit risk

Issuer Non-Diversification Risk: the risk of focusing investments in a small number of issuers, including being more susceptible to risks associated with a single economic, political or regulatory occurrence than a more diversified portfolio might be. Funds that are "non-diversified" may invest a greater percentage of their assets in the securities of a single issuer (such as bonds issued by a particular state) than funds that are "diversified"

Leveraging Risk: the risk that certain transactions of the Fund, such as reverse repurchase agreements, loans of portfolio securities, and the use of when-issued, delayed delivery or forward commitment transactions, or derivative instruments, may give rise to leverage, magnifying gains and losses and causing the Fund to be more volatile than if it had not been leveraged. This means that leverage entails a heightened risk of loss

Management Risk: the risk that the investment techniques and risk analyses applied by PIMCO will not produce the desired results and that legislative, regulatory, or tax restrictions, policies or developments may affect the investment techniques available to PIMCO and the individual portfolio manager in connection with managing the Fund. There is no guarantee that the investment objective of the Fund will be achieved

California State-Specific Risk: the risk that by concentrating its investments in California Municipal Bonds, the Fund may be affected significantly by economic, regulatory or political developments affecting the ability of California issuers to pay interest or repay principal

New York State-Specific Risk: the risk that by concentrating its investments in New York Municipal Bonds, the Fund may be affected significantly by economic, regulatory or political developments affecting the ability of New York issuers to pay interest or repay principal

Municipal Project-Specific Risk: the risk that the Fund may be more sensitive to adverse economic, business or political developments if it invests a substantial portion of its assets in the bonds of similar projects (such as those relating to education, health care, housing, transportation, and utilities), industrial development bonds, or in bonds from issuers in a single state

Short Sale Risk: the risk of entering into short sales, including the potential loss of more money than the actual cost of the investment, and the risk that the third party to the short sale may fail to honor its contract terms, causing a loss to the Fund

Please see "Description of Principal Risks" in the Fund's prospectus for a more detailed description of the risks of 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.

Performance Information

The performance information shows summary performance information for the Fund 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 its performance from year to year and by showing how the Fund's average annual returns compare with the returns of a broad- based securities market index and an index of similar funds. Absent any applicable fee waivers and/or expense limitations performance would have been lower. The bar chart shows performance of the Fund's Institutional Class shares. The Class R and the Administrative Class of the Fund are not operational as of the date of this prospectus. Performance for Class A and Class C shares in the Average Annual Total Returns table reflects the impact of sales charges. The Fund's past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future .

Effective September 1, 2015, the Fund's broad-based securities market index is the Barclays 1-15 Year Municipal Bond Index. The Barclays 1-15 Year Municipal Bond Index is the 1-15 Year (1-17) component of the Barclays Municipal Bond Index. The Barclays Municipal Bond Index is a rules-based, market-value-weighted index engineered for the long term tax-exempt bond market. To be included in the Index, bonds must be rated investment-grade (Baa3/BBB- or higher) by at least two of the following ratings agencies: Moody's, S&P and Fitch. If only two of the three agencies rate the security, the lower rating is used to determine index eligibility. If only one of the three agencies rates a security, the rating must be investment-grade. They must have an outstanding par value of at least $7 million and be issued as part of a transaction of at least $75 million. The bonds must be fixed rate, have a dated-date after December 31, 1990, and must be at least one year from their maturity date. Remarketed issues, taxable municipal bonds, bonds with floating rates, and derivatives, are excluded from the benchmark. The Fund's new broad-based securities market index was selected as its use is more closely aligned with the Fund's principal investment strategies. Prior to September 1, 2015, the Fund's broad-based securities market index was the Barclays Municipal Bond 1-20 Year Blend (1-22) Index. The Barclays Municipal Bond 1-20 Year Blend (1-22) Index is the 1-20 Year Blend (1-22) component of the Barclays Municipal Bond Index. The Lipper Intermediate Municipal Debt Funds Average is a total return performance average of Funds tracked by Lipper, Inc. that invest in municipal debt issues with dollar-weighted average maturities of five to ten years.

Performance for the Fund is updated daily and quarterly and may be obtained as follows: daily updates on the net asset value and performance page at http://investments.pimco.com/DailyPerformance and quarterly updates at http://investments.pimco.com/QuarterlyPerformance.

Calendar Year Total Returns — Institutional Class*

JULY 31, 2015 (as supplemented June 1, 2016) | SUMMARY PROSPECTUS 3

PIMCO National Intermediate Municipal
Bond Fund

*The year-to-date return as of June 30, 2015 is -0.31%. For the periods shown in the bar chart, the highest quarterly return was 2.47% in the Q1 2014, and the lowest quarterly return was -2.91% in the Q2 2013.

Average Annual Total Returns (for periods ended 12/31/14)

	1 Year		Since Inception (05/31/2012)
Institutional Class Return Before Taxes	6.97	%	3.44	%
Institutional Class Return After Taxes on Distributions‌(1)	6.97	%	3.42	%
Institutional Class Return After Taxes on Distributions and Sales of Fund Shares‌(1)	4.87	%	3.03	%
Class P Return Before Taxes	6.87	%	3.34	%
Class D Return Before Taxes	6.60	%	3.09	%
Class A Return Before Taxes	4.19	%	1.58	%
Class C Return Before Taxes	5.07	%	2.59	%
Barclays 1-15 Year Municipal Bond Index (reflects no deductions for fees, expenses or taxes)	6.36	%	2.84	%
Barclays Municipal Bond 1-20 Year Blend (1-22) Index (reflects no deductions for fees, expenses or taxes)	7.46	%	3.16	%

Lipper Intermediate Municipal Debt Funds Average (reflects no deductions for taxes) 5.91 % 2.19 %

(1) After-tax returns are calculated using the highest historical 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, and the after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. In some cases the return after taxes may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period. After-tax returns are for Institutional Class shares only. After-tax returns for other classes will vary.

Investment Adviser/Portfolio Manager

PIMCO serves as the investment adviser for the Fund. The Fund's portfolio is jointly managed by Julie Callahan and David Hammer. Ms. Callahan is a Senior Vice President of PIMCO, and she has managed the Fund since August 2015. Mr. Hammer is an Executive Vice President of PIMCO, and he has managed the Fund since June 2016.

Purchase and Sale of Fund Shares

Fund shares may be purchased or sold (redeemed) on any business day (normally any day when the New York Stock Exchange is open). Generally, purchase and redemption orders for Fund shares are processed at the net asset value next calculated after an order is received by the Fund.

Institutional Class, Class P, Administrative Class and Class D

The minimum initial investment for Institutional Class, Class P or Administrative Class shares of the Fund is $1 million, except that the minimum initial investment may be modified for certain financial firms that submit orders on behalf of their customers.

The minimum initial investment for Class D shares of the Fund is $1,000, except that the minimum initial investment may be modified for certain financial firms that submit orders on behalf of their customers. The minimum subsequent investment for Class D shares is $50.

You may sell (redeem) all or part of your Institutional Class, Class P, Administrative Class and Class D shares of the Fund on any business day. If you are the registered owner of the shares on the books of the Fund, depending on the elections made on the Account Application, you may sell by:

■

Sending a written request by mail to:
PIMCO Funds c/o BFDS Midwest
330 W. 9th Street, Kansas City, MO 64105

■

Calling us at 888.87.PIMCO and a Shareholder Services associate will assist you

■

Sending a fax to our Shareholder Services department at 816.421.2861

■

Sending an e-mail to pimcoteam@bfdsmidwest.com

Class A, Class C and Class R

The minimum initial investment for Class A and Class C shares of the Fund is $1,000. The minimum subsequent investment for Class A and Class C shares is $50. The minimum initial investment may be modified for certain financial firms that submit orders on behalf of their customers. You may purchase or sell (redeem) all or part of your Class A and Class C shares through a broker-dealer, or other financial firm, or, if you are the registered owner of the shares on the books of the Fund, by regular mail to PIMCO Funds, P.O. Box 55060, Boston, MA 02205-5060 or overnight mail to PIMCO Funds, c/o Boston Financial Data Services, Inc., 30 Dan Road, Canton, MA 02021-2809. The Fund reserves the right to require payment by wire or U.S. Bank check in connection with accounts opened directly with the Fund by Account Application.

There is no minimum initial or minimum subsequent investment in Class R shares because Class R shares may only be purchased through omnibus accounts for specified benefit plans. Specified benefit plans that wish to invest directly by mail should send a check payable to the PIMCO Family of Funds, along with a completed Account Application, by regular mail to PIMCO Funds, P.O. Box 55060, Boston, MA 02205-5060 or overnight mail to PIMCO Funds, c/o Boston Financial Data Services, Inc., 30 Dan Road, Canton, MA 02021-2809.

Tax Information

The Fund's distributions are generally taxable to you as ordinary income, capital gains, or a combination of the two, unless you are investing through a tax-deferred arrangement, such as a 401(k) plan or an individual retirement account, in which case distributions may be taxable upon withdrawal. Distributions paid by the Fund that are properly designated as
"exempt interest dividends" normally will be exempt from federal income taxes, but may not be exempt from the federal alternative minimum tax.

4      SUMMARY PROSPECTUS | PIMCO FUNDS     

Summary Prospectus

Payments to Broker-Dealers and Other Financial Firms

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

JULY 31, 2015 (as supplemented June 1, 2016) | SUMMARY PROSPECTUS 5

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