Putnam Convertible Securities 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 2/28/18, are incorporated by reference into this summary prospectus.

Goal

Putnam Convertible Securities Fund seeks, with equal emphasis, current income and capital appreciation. Its secondary objective is conservation of capital.

Fees and expenses

The following table describes 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 $50,000 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 13 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	5.75%	1.00%*
Class B	NONE	5.00%**
Class C	NONE	1.00%***
Class M	3.50%	NONE
Class R	NONE	NONE
Class T	2.50%	NONE
Class Y	NONE	NONE

2          

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
Class A	0.63%	0.25%	0.19%	1.07%
Class B	0.63%	1.00%	0.19%	1.82%
Class C	0.63%	1.00%	0.19%	1.82%
Class M	0.63%	0.75%	0.19%	1.57%
Class R	0.63%	0.50%	0.19%	1.32%
Class T	0.63%	0.25%	0.19%<	1.07%
Class Y	0.63%	N/A	0.19%	0.82%

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

**   This charge is phased out over six years.

***   This charge is eliminated after one year.

<   Other expenses are based on expenses of class A shares for the fund’s last fiscal year.

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. Your actual costs may be higher or lower.

Share class	1 year	3 years	5 years	10 years
Class A	$678	$896	$1,131	$1,806
Class B	$685	$873	$1,185	$1,940
Class B (no redemption)	$185	$573	$985	$1,940
Class C	$285	$573	$985	$2,137
Class C (no redemption)	$185	$573	$985	$2,137
Class M	$504	$828	$1,175	$2,152
Class R	$134	$418	$723	$1,590
Class T	$356	$582	$825	$1,523
Class Y	$84	$262	$455	$1,014

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 56%.

3

Investments, risks, and performance

Investments

We invest mainly in convertible securities of U.S. companies. Under normal circumstances, we invest at least 80% of the fund’s net assets in convertible securities. This policy may be changed only after 60 days’ notice to shareholders. Convertible securities combine the investment characteristics of bonds and common stocks. Convertible securities include bonds, preferred stocks and other instruments that can be converted into or exchanged for common stock or equivalent value. A significant portion of the convertible securities we buy are below-investment-grade (sometimes referred to as “junk bonds”). The convertible bonds we buy usually have intermediate-to long-term stated maturities (i.e., three years or longer), but often contain “put” features, which allow bondholders to sell the bond back to the company under specified circumstances, that result in shorter effective maturities. When deciding whether to buy or sell investments, we may consider, among other factors: (i) a security’s structural features, such as its position in a company’s capital structure and “put” and “call” features (a company’s right to repurchase the security under specified circumstances is a “call” feature); (ii) credit and prepayment risks; and (iii) with respect to a company’s common stock underlying a convertible security, the stock’s valuation and the company’s financial strength, growth potential, competitive position in its industry, projected future earnings, cash flows and dividends.

Risks

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

The value of convertible securities in the fund’s portfolio may fall or fail to rise over extended periods of time for a variety of reasons, including general financial market conditions, changing market perceptions (including perceptions about the risk of default and expectations about monetary policy or interest rates), changes in government intervention in the financial markets, and factors related to a specific issuer or industry. These and other factors may lead to increased volatility and reduced liquidity in the fund’s portfolio holdings. These risks are generally greater for convertible securities issued by small and midsize companies (which may constitute a significant portion of the fund’s investments from time to time). The value of convertible securities may be adversely affected by changes in the prices of underlying common stocks. Convertible securities tend to provide higher yields than common stocks. However, a higher yield may not protect investors against the risk of loss or adequately mitigate any loss associated with a decline in the price of a convertible security. Convertible securities are subject to credit risk, which is the risk that an issuer of the fund’s investments may default on payment of interest or principal. Credit risk is generally greater for below-investment-grade convertible securities (a significant part of the fund’s investments). Generally, convertible securities may be less sensitive to interest rate changes than non-convertible bonds as a result of convertible securities’ convertibility and “put” features. Interest rate risk is generally greater for longer-term bonds and convertible securities whose underlying stock price has fallen significantly below the conversion price.

4          

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 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

Average annual total returns after sales charges
(for periods ending 12/31/17)

Share class	1 year	5 years	10 years
Class A before taxes	8.32%	7.65%	5.64%
Class A after taxes on distributions	7.07%	6.27%	4.51%
Class A after taxes on distributions and sale of fund shares	5.26%	5.56%	4.09%
Class B before taxes	9.10%	7.83%	5.63%
Class C before taxes	13.09%	8.12%	5.48%
Class M before taxes	10.32%	7.62%	5.36%
Class R before taxes	14.61%	8.66%	6.00%
Class T before taxes*	12.06%	8.38%	6.00%
Class Y before taxes	15.24%	9.21%	6.54%
ICE BofAML U.S. Convertible Index (no deduction for fees, expenses or taxes)	13.70%	10.74%	7.35%

*   Class T shares were not outstanding during the periods shown. Performance shown for class T shares is derived from the historical performance of class A shares, adjusted for the lower initial sales charge currently applicable to class T shares.

ICE BofAML Indexes: ICE Data Indices, LLC (“ICE BofAML”), used with permission. ICE BofAML permits use of the ICE BofAML 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 BofAML indices or any data included in, related to, or derived therefrom; assumes no liability in

5

connection with the use of the foregoing; and does not sponsor, endorse, or recommend Putnam Investments, or any of its products or services.

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.

Class B share performance reflects conversion to class A shares after eight years.

Your fund’s management

Investment advisor

Putnam Investment Management, LLC

Portfolio managers

Robert Salvin
Portfolio Manager, portfolio manager
of the fund since 2006

Anthony Daigle
Portfolio Manager, Analyst, portfolio
manager of the fund since 2017

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. Purchases for class B shares are closed to new and existing investors except by exchange from class B shares of another Putnam fund or through dividend and/or capital gains reinvestment.

When opening an account, you must complete and mail a Putnam account application, along with a check made payable to the fund, to: Putnam Investor Services, P.O. Box 8383, Boston, MA 02266-8383. 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.

6          

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.

7