Putnam Mortgage Opportunities Fund

Before you invest, you may wish to review the fund’s prospectus, which contains more information about the fund and its risks. You may obtain the prospectus and other information about the fund, including the statement of additional information (SAI) and most recent reports to shareholders, at no cost by visiting putnam.com/funddocuments, calling 1-800-225-1581, or e-mailing Putnam at funddocuments@putnam.com.

The fund’s prospectus and SAI, both dated 5/30/20, are incorporated by reference into this summary prospectus.

Goal

Putnam Mortgage Opportunities Fund seeks to maximize total return consistent with what Putnam Investment Management, LLC believes to be prudent risk. Total return is composed of capital appreciation and income.

Fees and expenses

The following tables describe the fees and expenses 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 Putnam funds. More information about these and other discounts is available from your financial advisor and in How do I buy fund shares? beginning on page 16 of the fund’s prospectus, in the Appendix to the fund’s prospectus, and in How to buy shares beginning on page II-1 of the fund’s Statement of Additional Information (SAI).

Shareholder fees (fees paid directly from your investment)

Share class	Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, whichever is lower)
Class A	4.00%	1.00%*
Class C	NONE	1.00%**
Class R6	NONE	NONE
Class Y	NONE	NONE

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

Share class	Management fees	Distribution and service (12b-1) fees	Other expenses<	Total annual fund operating expenses	Expense reimbursement#	Total annual fund operating expenses after expense reimbursement
Class A	0.55%	0.25%	0.28%	1.08%	(0.21)%	0.87%
Class C	0.55%	1.00%	0.28%	1.83%	(0.21)%	1.62%
Class R6	0.55%	N/A	0.18%	0.73%	(0.21)%	0.52%
Class Y	0.55%	N/A	0.28%	0.83%	(0.21)%	0.62%

*   Applies only to certain redemptions of shares bought with no initial sales charge.

**   This charge is eliminated after one year.

<   Other expenses are based on expenses of class I shares (which are not offered in this prospectus) for the fund’s last fiscal year, restated to reflect the higher investor servicing fees applicable to class A, C, R6, and Y shares.

#   Reflects Putnam Investment Management, LLC’s (“Putnam Management”) contractual obligation to limit certain fund expenses through May 31, 2021. This obligation may be modified or discontinued only with approval of the Board of Trustees.

Example

The following hypothetical example is intended to help you compare the cost of investing in the fund with the cost of investing in other funds. It assumes that you invest $10,000 in the fund for the time periods indicated and then, except as indicated, redeem all your shares at the end of those periods. It assumes a 5% return on your investment each year and that the fund’s operating expenses remain the same. Only the first year of each period in the example takes into account the expense reimbursement described above. Your actual costs may be higher or lower.

Share class	1 year	3 years	5 years	10 years
Class A	$485	$710	$952	$1,646
Class C	$265	$555	$971	$2,131
Class C (no redemption)	$165	$555	$971	$2,131
Class R6	$53	$212	$385	$887
Class Y	$63	$244	$440	$1,006

Portfolio turnover

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs and may result in higher taxes when the fund’s shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 1,012%.

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Investments, risks, and performance

Investments

We invest mainly in mortgage-related fixed income securities and related derivatives that are either investment-grade or below-investment-grade in quality (sometimes referred to as “junk bonds”). Under normal circumstances, we invest at least 80% of the fund’s net assets in mortgages, mortgage-related fixed income securities and related derivatives (i.e., derivatives used to acquire exposure to, or whose underlying securities are, mortgages or mortgage-related securities). The fund generally uses the net unrealized gain or loss, or market value, of mortgage-related derivatives for purposes of this policy, but may use the notional value of a derivative if that is determined to be a more appropriate measure of the fund’s investment exposure. This policy may be changed only after 60 days’ notice to shareholders.

We expect to invest in lower-rated, higher-yielding mortgage-backed securities, including non-agency residential mortgage-backed securities (which may be backed by non-qualified or “sub-prime” mortgages), commercial mortgage-backed securities, collateralized mortgage obligations (including interest only, principal only, and other prepayment derivatives), and agency mortgage-backed securities. Non-agency (i.e., privately issued) securities typically are lower-rated and higher yielding than securities issued or backed by agencies such as Ginnie Mae, Fannie Mae or Freddie Mac. While our emphasis will be on mortgage-backed securities, we may also invest to a lesser extent in other types of asset-backed securities. We may consider, among other factors, credit, interest rate, prepayment and liquidity risks, as well as general market conditions, when deciding whether to buy or sell investments. We typically use to a significant extent derivatives, including interest rate swaps, forward delivery contracts and total return swaps, options and swaptions on mortgage-backed securities and indices, for both hedging and non-hedging purposes, including to obtain or adjust exposure to mortgage-backed investments.

Risks

It is important to understand that you can lose money by investing in the fund.

The value of investments in the fund’s portfolio may fall or fail to rise over extended periods of time for a variety of reasons, including general economic, political or financial market conditions, investor sentiment and market perceptions, government actions, geopolitical events or changes, and factors related to a specific issuer, geography, industry or sector, such as the housing or real estate markets. These and other factors may lead to increased volatility and reduced liquidity in the fund’s portfolio holdings or in relevant markets.

The risks associated with bond investments include interest rate risk, which means the value of the fund’s investments is likely to fall if interest rates rise. Bond investments are also subject to credit risk, which is the risk that the issuers of the fund’s investments may default on payment of interest or principal. Default risk is generally higher for non-qualified mortgages. Interest rate risk is generally greater for longer-term bonds, and credit risk is generally greater for below-investment-grade bonds, which may be considered speculative. Mortgage- and asset-backed investments, unlike traditional debt investments, are also subject to prepayment risk, which means that they may increase in value less than other bonds when interest rates decline and decline in value more than other bonds when interest rates rise. We may have to invest the proceeds from prepaid investments, including mortgage- and

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asset-backed investments, in other investments with less attractive terms and yields. The fund’s investments in mortgage-backed securities and asset-backed securities, and in certain other securities and derivatives, may be or become illiquid. The fund’s concentration in an industry group composed of privately issued mortgage-backed securities and mortgage-backed securities issued or guaranteed by the U.S. government or its agencies or instrumentalities may make the fund’s net asset value more susceptible to economic, market, political and other developments affecting the residential and commercial real estate markets.

Our use of derivatives may increase the risks of investing in the fund by increasing investment exposure (which may be considered leverage) or, in the case of many over-the-counter instruments, because of the potential inability to terminate or sell derivatives positions and the potential failure of the other party to the instrument to meet its obligations.

The fund expects to engage in frequent trading. Funds with high turnover may be more likely to realize capital gains that must be distributed to shareholders as taxable income and may incur higher transaction costs than funds with relatively lower turnover, which may detract from performance.

There is no guarantee that the investment techniques, analyses, or judgments that we apply in making investment decisions for the fund will produce the intended outcome or that the investments we select for the fund will perform as well as other securities that were not selected for the fund. We, or the fund’s other service providers, may experience disruptions or operating errors that could negatively impact the fund.

The fund may not achieve its goal, and it is not intended to be a complete investment program. An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Performance

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The performance shown is that of class I shares of the fund, which are not offered in this prospectus, and this performance has been adjusted to reflect the higher fees associated with class A, C, R6 and Y shares of the fund. The bar chart does not reflect the impact of sales charges. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results. Monthly performance figures for the fund are available at putnam.com.

Annual total returns for class A shares before sales charges

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Average annual total returns after sales charges (for periods ended 12/31/19)

Share class	1 year	Since Inception (4/7/15)
Class A before taxes*	5.58%	3.64%
Class A after taxes on distributions*	3.37%	2.03%
Class A after taxes on distributions and sale of fund shares*	3.29%	2.06%
Class C before taxes*	8.16%	3.76%
Class R6 before taxes**	10.40%	4.96%
Class Y before taxes*	10.22%	4.81%
ICE BofA U.S. Treasury Bill Index*** (no deduction for fees, expenses or taxes)	2.35%	1.15 %
Bloomberg Barclays U.S. MBS Index (no deduction for fees, expenses or taxes)	6.35%	2.47%

*   Performance for class A, C, and Y shares prior to their inception (7/1/19) is derived from the historical performance of class I shares and has been adjusted for the higher fees applicable to class A, C, and Y shares.

**   Performance for class R6 shares prior to their inception (6/1/20) is derived from the historical performance of class I shares and has been adjusted for the higher investor servicing fees applicable to class R6 shares.

***   ICE Data Indices, LLC (“ICE BofA”), used with permission. ICE BofA permits use of the ICE BofA indices and related data on an “as is” basis; makes no warranties regarding same; does not guarantee the suitability, quality, accuracy, timeliness, and/or completeness of the ICE BofA indices or any data included in, related to, or derived therefrom; assumes no liability in connection with the use of the foregoing; and does not sponsor, endorse, or recommend Putnam Investments, or any of its products or services.

The fund’s performance is compared to the ICE BofA U.S. Treasury Bill Index, an unmanaged index that tracks the performance of U.S. dollar denominated U.S. Treasury bills, which represent obligations of the U.S. Government having a maturity of one year or less. The fund’s performance is also compared to the Bloomberg Barclays U.S. Mortgage Backed Securities (MBS) Index, an unmanaged index that tracks agency mortgage pass-through securities (both fixed-rate and hybrid adjustable-rate mortgages) guaranteed by Ginnie Mae (GNMA), Fannie Mae (FNMA), and Freddie Mac (FHLMC). Securities in the fund do not match those in the indexes and the performance of the fund will differ.

After-tax returns reflect the historical highest individual federal marginal income tax rates and do not reflect state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are shown for class A shares only and will vary for other classes. These after-tax returns do not apply if you hold your fund shares through a 401(k) plan, an IRA, or another tax-advantaged arrangement.

Your fund’s management

Investment advisor

Putnam Investment Management, LLC

Portfolio managers

Michael Salm
Co-Head of Fixed Income, portfolio
manager of the fund since 2015

Brett Kozlowski
Portfolio Manager, portfolio manager
of the fund since 2015

Jatin Misra
Portfolio Manager, portfolio manager
of the fund since 2015

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Sub-advisor

Putnam Investments Limited*

*   Though the investment advisor has retained the services of Putnam Investments Limited (PIL), PIL does not currently manage any assets of the fund.

Purchase and sale of fund shares

You can open an account, purchase and/or sell fund shares, or exchange them for shares of another Putnam fund by contacting your financial advisor or by calling Putnam Investor Services at 1-800-225-1581.

When opening an account, you must complete and mail a Putnam account application, along with a check made payable to the fund, to: Putnam Investments, P.O. Box 219697, Kansas City, MO 64121-9697. The minimum initial investment of $500 is currently waived, although Putnam reserves the right to reject initial investments under $500 at its discretion. There is no minimum for subsequent investments.

You can sell your shares back to the fund or exchange them for shares of another Putnam fund any day the New York Stock Exchange (NYSE) is open. Shares may be sold or exchanged by mail, by phone, or online at putnam.com. Some restrictions may apply.

Tax information

The fund's distributions will be taxed as ordinary income or capital gains unless you hold the shares through a tax-advantaged arrangement, in which case you will generally be taxed only upon withdrawal of monies from the arrangement.

Financial intermediary compensation

If you purchase the fund through a broker/dealer or other financial intermediary (such as a bank or financial advisor), the fund and its related companies may pay that intermediary for the sale of fund shares and related services. Please bear in mind that these payments may create a conflict of interest by influencing the broker/dealer or other intermediary to recommend the fund over another investment. Ask your advisor or visit your advisor's website for more information.

Information about the Summary Prospectus, Prospectus, and SAI

The summary prospectus, prospectus, and SAI for a fund provide information concerning the fund. The summary prospectus, prospectus, and SAI are updated at least annually and any information provided in a summary prospectus, prospectus, or SAI can be changed without a shareholder vote unless specifically stated otherwise. The summary prospectus, prospectus, and the SAI are not contracts between the fund and its shareholders and do not give rise to any contractual rights or obligations or any shareholder rights other than any rights conferred explicitly by federal or state securities laws that may not be waived.

Additional information, including current performance, is available at putnam.com/funddocuments, by calling 1-800-225-1581, or by e-mailing Putnam at funddocuments@putnam.com.