Filing by Investment Company (SEC Filing - 497K)

Summary Prospectus

July 30, 2021

Share Class:	Inst	I-2	Admin
Ticker:	PMBIX	PMTPX	PRADX

As permitted by regulations adopted by the Securities and Exchange Commission, paper copies of the Fund's annual and semi-annual shareholder reports will no longer be sent by mail, unless you specifically request paper copies of the reports from the Fund or from your financial intermediary, such as a broker-dealer or bank. Instead, the reports will be made available on the Fund's website, pimco.com/literature, and you will be notified by mail each time a report is posted and provided with a website link to access the report.

If you already elected to receive shareholder reports electronically, you will not be affected by this change and you need not take any action. You may elect to receive shareholder reports and other communications from the Fund electronically by visiting pimco.com/edelivery or by contacting your financial intermediary, such as a broker-dealer or bank.

You may elect to receive all future reports in paper free of charge. If you own these shares through a financial intermediary, such as a broker-dealer or bank, you may contact your financial intermediary to request that you continue to receive paper copies of your shareholder reports. If you invest directly with the Fund, you can inform the Fund that you wish to continue receiving paper copies of your shareholder reports by calling 888.87.PIMCO (888.877.4626). Your election to receive reports in paper will apply to all funds held with the fund complex if you invest directly with the Fund or to all funds held in your account if you invest through a financial intermediary, such as a broker-dealer or bank.

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, reports to shareholders (once available) 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 [email protected]. The Fund's prospectus and Statement of Additional Information, dated July 30, 2021, respectively, as supplemented, are incorporated by reference into this Summary Prospectus.

Investment Objective

The Fund seeks maximum total return, consistent with preservation of capital and prudent investment management.

Fees and Expenses of the Fund

This 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 commissions and other fees to financial intermediaries, which are not reflected in the table and example below.

Shareholder Fees (fees paid directly from your investment):

None

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

	Inst Class	I-2	Admin Class
Management Fees	0.50%	0.60%	0.50%
Distribution and/or Service (12b-1) Fees	N/A	N/A	0.25%
Total Annual Fund Operating Expenses	0.50%	0.60%	0.75%

Example.The Example is intended to help you compare the cost of investing in Institutional Class, I-2 or Administrative Class 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:

	1 Year	3 Years	5 Years	10 Years
Institutional Class	$51	$160	$280	$628
I-2	$61	$192	$335	$750
Administrative Class	$77	$240	$417	$930

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 483% 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 65% of its total assets in a diversified portfolio of Fixed Income Instruments of varying maturities, which may be represented by forwards or derivatives such as options, futures contracts, or swap agreements. 'Fixed Income Instruments' include bonds, debt securities and other similar instruments issued by various U.S. public- or private-sector entities. The average portfolio duration of this Fund normally varies within two years (plus or minus) of the portfolio duration of the securities comprising the Bloomberg Barclays U.S. Aggregate Index, as calculated by Pacific Investment Management Company LLC ('PIMCO'), which as of May 31, 2021 was 6.19 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 Fund may invest only in investment grade U.S. dollar denominated securities of U.S. issuers that are rated at least Baa 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, without limitation, in derivative instruments, such as options, futures contracts or swap agreements, or in mortgage- or asset-backed securities, subject to applicable law and any other restrictions described in the Fund's prospectus or Statement of Additional Information. 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, 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 'total return' sought by the Fund consists of income earned on the Fund's investments, plus capital appreciation, if any, which generally arises

from decreases in interest rates or improving credit fundamentals for a particular sector or security. The Fund may also invest up to 10% of its total assets in preferred securities.

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 listed below.

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, or is perceived (whether by market participants, rating agencies, pricing services or otherwise) as unable or unwilling, to meet its financial obligations

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 investments 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 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 leverage, liquidity, interest rate, market, credit and management risks, and valuation complexity. Changes in the value of a 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 ('OTC') derivatives are also subject to the risk that a counterparty to the transaction will not fulfill its contractual obligations to the other party, as many of the protections afforded to centrally-cleared derivative transactions might not be available for OTC derivatives. The primary credit risk on derivatives that are exchange-traded or traded through a central clearing counterparty resides with the Fund's clearing broker or the clearinghouse. Changes in regulation relating to a mutual fund's use of derivatives and related instruments could potentially limit or impact the Fund's ability to invest in derivatives, limit the Fund's ability to employ certain strategies that use derivatives and/or adversely affect the value of derivatives and the Fund's performance

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

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 actual or potential conflicts of interest, 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 and may cause PIMCO to restrict or prohibit participation in certain investments. There is no guarantee that the investment objective of the Fund will be achieved

Short Exposure 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 will not fulfill its contractual obligations, causing a loss to the Fund

LIBOR Transition Risk:the risk related to the anticipated discontinuation of the London Interbank Offered Rate ('LIBOR'). Certain instruments held by the Fund rely in some fashion upon LIBOR. Although the transition process away from LIBOR has become increasingly well-defined in advance of the anticipated discontinuation date, there remains uncertainty regarding the nature of any replacement rate, and any potential effects of the transition away from LIBOR on the Fund or on certain instruments in which the Fund invests can be difficult to ascertain. The transition process may involve, among other things,

increased volatility or illiquidity in markets for instruments that currently rely on LIBOR and may result in a reduction in the value of certain instruments held by 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 Fund's past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.

The Bloomberg Barclays U.S. Aggregate Index represents securities that are SEC-registered, taxable, and dollar denominated. The index covers the U.S. investment grade fixed rate bond market, with index components for government and corporate securities, mortgage pass-through securities, and asset-backed securities. These major sectors are subdivided into more specific indices that are calculated and reported on a regular basis. The Lipper Core Plus Bond Funds Average is a total return performance average of Funds tracked by Lipper, Inc. that invest at least 65% in domestic investment-grade debt issues (rated in the top four grades) with any remaining investment in non-benchmark sectors such as high-yield, global and emerging market debt. These funds maintain 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 and quarterly updates on the net asset value and performance page at https://www.pimco.com/en-us/product-finder.

Calendar Year Total Returns - Institutional Class

Best Quarter	June 30, 2020	3.71%
Worst Quarter	June 30, 2013	-3.30%
Year-to-Date	June 30, 2021	-1.45%

Average Annual Total Returns (for periods ended 12/31/20)

	1 Year	5 Years	10 Years
Institutional Class Return Before Taxes	8.34%	5.08%	3.92%
Institutional Class Return After Taxes on Distributions(1)	5.61%	3.37%	2.31%
Institutional Class Return After Taxes on Distributions and Sales of Fund Shares(1)	5.21%	3.18%	2.41%
I-2 Return Before Taxes	8.24%	4.97%	3.82%
Administrative Class Return Before Taxes	8.07%	4.82%	3.66%
Bloomberg Barclays U.S. Aggregate Index (reflects no deductions for fees, expenses or taxes)	7.51%	4.44%	3.84%
Lipper Core Plus Bond Funds Average (reflects no deductions for taxes)	9.18%	5.06%	4.31%

Investment Adviser/Portfolio Managers

PIMCO serves as the investment adviser for the Fund. The Fund's portfolio is jointly and primarily managed by Scott Mather, Mark Kiesel and Mohit Mittal. Mr. Mather is CIO U.S. Core Strategies. Mr. Kiesel is CIO Global Credit. Each of Messrs. Mather, Kiesel and Mittal is a Managing Director of PIMCO. Messrs. Mather and Kiesel have jointly and primarily managed the Fund since September 2014, and Mr. Mittal has jointly and primarily managed the Fund since December 2019.

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 ('NYSE') 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, I-2, and Administrative Class

The minimum initial investment for Institutional Class, I-2, and 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.

You may sell (redeem) all or part of your Institutional Class, I-2, and Administrative Class 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:

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.

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.