Pioneer Equity Income Fund

Class A Shares (PEQIX)	Class C Shares (PCEQX)	Class K Shares (PEQKX)
Class R Shares (PQIRX)	Class Y Shares (PYEQX)

Summary Prospectus

March 1, 2016

Before you invest, you may want to review the fund’s prospectus, which contains more information about the fund and its risks. You can find the fund’s prospectus, statement of additional information and other information about the fund online at http://us.pioneerinvestments.com/misc/prospectus.jsp. You also can obtain this information at no cost by calling 1-800-225-6292 or by sending an email request to ask.pioneer@pioneerinvestments.com. The fund’s current prospectus and statement of additional information, dated March 1, 2016, and the independent registered public accounting firm’s report and financial statements in the fund’s annual report to shareholders dated October 31, 2015, are incorporated by reference into this summary prospectus.

Investment objectives

Current income and long-term growth of capital from a portfolio consisting primarily of income producing equity securities of U.S. corporations.

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 or your family invest, or agree to invest in the future, at least $50,000 in Class A shares of the Pioneer funds. More information about these and other discounts is available from your investment professional and in the “Sales charges” section of the prospectus beginning on page 36 and the “Sales charges” section of the statement of additional information beginning on page 52.

Summary Prospectus

Shareowner fees
(fees paid directly from your investment)	Class A	Class C	Class K	Class R	Class Y
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	5.75%	None	None	None	None
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	None¹	1%	None	None	None

Annual fund operating expenses
(expenses that you pay each year as a percentage of the value of your investment)	Class A	Class C	Class K	Class R	Class Y
Management Fees	0.60%	0.60%	0.60%	0.60%	0.60%
Distribution and Service (12b-1) Fees	0.25%	1.00%	0.00%	0.50%	0.00%
Other Expenses	0.21%	0.20%	0.07%	0.31%	0.18%
Total Annual Fund Operating Expenses	1.06%	1.80%	0.67%	1.41%	0.78%

1	Class A purchases of $500,000 or more that are not subject to an initial sales charge may be subject to a contingent deferred sales charge of 1%. See “Sales charges.”

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 $10,000 in the fund for the time periods shown and then, except as indicated, redeem all of your shares at the end of those periods. It also assumes that (a) your investment has a 5% return each year and (b) the fund's total annual 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				If you do not redeem your shares
	Number of years you own your shares
	1	3	5	10	1	3	5	10
Class A	$677	$893	$1,126	$1,795	$677	$893	$1,126	$1,795
Class C	283	566	975	2,116	183	566	975	2,116
Class K	68	214	373	835	68	214	373	835
Class R	144	446	771	1,691	144	446	771	1,691
Class Y	80	249	433	966	80	249	433	966

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 annual fund operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 40% of the average value of its portfolio.

Principal investment strategies

Normally, the fund invests at least 80% of its total assets in income producing equity securities of U.S. issuers. The income producing equity securities in which the fund may invest include common stocks, preferred stocks, exchange-traded funds (ETFs) that invest primarily in equity securities and equity interests in real estate investment trusts (REITs). The remainder of the fund may be invested in debt securities, most of which are expected to be convertible into common stocks. The fund may invest in initial public offerings of equity securities.

The fund may invest up to 20% of its total assets in securities of non-U.S. issuers, including depositary receipts. The fund will not invest more than 5% of its total assets in the securities of emerging markets issuers.

The fund may invest up to 20% of its net assets in REITs.

The fund also may invest in investment grade and below investment grade debt securities (known as “junk bonds”). The fund may invest up to 10% of its net assets in junk bonds, including below investment grade convertible debt securities.

The fund may, but is not required to, use derivatives, such as stock index futures and options. The fund may use derivatives for a variety of purposes, including; in an attempt to hedge against adverse changes in the market price of securities, interest rates or currency exchange rates; as a substitute for purchasing or selling securities; to attempt to increase the fund's return as a non-hedging strategy that may be considered speculative; to manage portfolio characteristics; and as a cash flow management technique. The fund may choose not to make use of derivatives for a variety of reasons, and any use may be limited by applicable law and regulations. The fund may also hold cash or other short-term investments.

Summary Prospectus

The fund's investment adviser uses a value approach to select the fund's investments to buy and sell. The adviser seeks securities that are selling at substantial discounts to their underlying values and then holds these securities until the market values reflect their intrinsic values. The adviser evaluates a security’s potential value, including the attractiveness of its market valuation, based on the company’s assets and prospects for earnings growth. The adviser also considers a security’s potential to provide a reasonable amount of income. In making these assessments, the adviser employs fundamental research and an evaluation of the issuer based on its financial statements and operations, employing a bottom-up analytic style, which focuses on specific securities rather than on industries. The adviser generally sells a portfolio security when it believes that the security’s market value reflects its underlying value.

Principal risks of investing in the fund

You could lose money on your investment in the fund. As with any mutual fund, there is no guarantee that the fund will achieve its objectives.

Market risk. The values of securities held by the fund may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political, or regulatory conditions, inflation, changes in interest or currency rates, lack of liquidity in the bond markets or adverse investor sentiment. In the past several years, financial markets, such as those in the United States, Europe, Asia and elsewhere, have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. Governmental and non-governmental issuers have defaulted on, or been forced to restructure, their debts. These conditions may continue, recur, worsen or spread. The U.S. government and the Federal Reserve, as well as certain foreign governments and their central banks, have taken steps to support financial markets, including by keeping interest rates at historically low levels. This and other government intervention may not work as intended, particularly if the efforts are perceived by investors as being unlikely to achieve the desired results. The Federal Reserve recently has reduced its market support activities. Further reduction or withdrawal of Federal Reserve or other U.S. or non-U.S. governmental or central bank support, including interest rate increases, could negatively affect financial markets generally, increase market volatility and reduce the value and liquidity of securities in which the fund invests. Policy and legislative changes in the U.S. and in other countries are affecting many aspects of financial regulation, and may in some

instances contribute to decreased liquidity and increased volatility in the financial markets. The impact of these changes on the markets, and the practical implications for market participants, may not be fully known for some time. Economies and financial markets throughout the world are becoming increasingly interconnected. As a result, whether or not the fund invests in securities of issuers located in or with significant exposure to countries experiencing economic and financial difficulties, the value and liquidity of the fund’s investments may be negatively affected. The fund may experience a substantial or complete loss on any individual security or derivative position.

Value style risk. The prices of securities the adviser believes are undervalued may not appreciate as expected or may go down. Value stocks may fall out of favor with investors and underperform the overall equity market.

Income producing securities risk. Income producing securities may fall out of favor with investors and underperform the overall equity market.

Large capitalization companies risk. Large capitalization companies may fall out of favor with investors and underperform the overall equity market.

Portfolio selection risk. The adviser's judgment about a particular security or issuer, or about the economy or a particular sector, region or market segment, or about an investment strategy, may prove to be incorrect.

Risks of non-U.S. investments. Investing in non-U.S. issuers, or in U.S. issuers that have significant exposure to foreign markets, may involve unique risks compared to investing in securities of U.S. issuers. These risks are more pronounced for issuers in emerging markets or to the extent that the fund invests significantly in one region or country. These risks may include different financial reporting practices and regulatory standards, less liquid trading markets, extreme price volatility, currency risks, changes in economic, political, regulatory and social conditions, sustained economic downturns, financial instability, tax burdens, and investment and repatriation restrictions. Lack of information and less market regulation also may affect the value of these securities. Withholding and other non-U.S. taxes may decrease the fund’s return. Non-U.S. issuers may be located in parts of the world that have historically been prone to natural disasters. Investing in depositary receipts is subject to many of the same

Summary Prospectus

risks as investing directly in non-U.S. issuers. Depositary receipts may involve higher expenses and may trade at a discount (or premium) to the underlying security. A number of countries in the European Union (EU) have experienced, and may continue to experience, severe economic and financial difficulties.

Risks of initial public offerings. Companies involved in initial public offerings (IPOs) generally have limited operating histories, and prospects for future profitability are uncertain. The market for IPO issuers has been volatile, and share prices of newly public companies have fluctuated significantly over short periods of time. The purchase of IPO shares may involve high transaction costs.

Risks of investment in other funds. Investing in other investment companies, including exchange-traded funds (ETFs), subjects the fund to the risks of investing in the underlying securities or assets held by those funds. When investing in another fund, the fund will bear a pro rata portion of the underlying fund’s expenses, in addition to its own expenses.

Risks of investments in real estate related securities. Investments in real estate securities are affected by economic conditions, interest rates, governmental actions and other factors. In addition, investing in REITs involves unique risks. They are significantly affected by the market for real estate and are dependent upon management skills and cash flow. REITs may have lower trading volumes and may be subject to more abrupt or erratic price movements than the overall securities markets. Mortgage REITs are particularly subject to interest rate and credit risks. In addition to its own expenses, the fund will indirectly bear its proportionate share of any management and other expenses paid by REITs in which it invests. Many real estate companies, including REITs, utilize leverage.

Risks of convertible securities. The market values of convertible securities tend to decline as interest rates increase and, conversely, to increase as interest rates decline. A downturn in equity markets may cause the price of convertible securities to decrease relative to other fixed income securities.

Preferred stocks risk. Preferred stocks may pay fixed or adjustable rates of return. Preferred stocks are subject to issuer-specific and market risks applicable generally to equity securities. In addition, a company’s preferred stocks generally pay dividends only after the company makes required payments to holders of its bonds and other debt. Thus, the value of

preferred stocks will usually react more strongly than bonds and other debt to actual or perceived changes in the company’s financial condition or prospects. The market value of preferred stocks generally decreases when interest rates rise. Preferred stocks of smaller companies may be more vulnerable to adverse developments than preferred stocks of larger companies.

Debt securities risk. Factors that could contribute to a decline in the market value of debt securities in the fund include rising interest rates, if the issuer or other obligor of a security held by the fund fails to pay principal and/or interest, otherwise defaults or has its credit rating downgraded or is perceived to be less creditworthy or the credit quality or value of any underlying assets declines. Junk bonds have a higher risk of default or are already in default and are considered speculative.

High yield or “junk” bond risk. Debt securities that are below investment grade, called “junk bonds,” are speculative, have a higher risk of default or are already in default, tend to be less liquid and are more difficult to value than higher grade securities. Junk bonds tend to be volatile and more susceptible to adverse events and negative sentiments. These risks are more pronounced for securities that are already in default.

Market segment risk. To the extent the fund emphasizes, from time to time, investments in a market segment, the fund will be subject to a greater degree to the risks particular to that segment, and may experience greater market fluctuation than a fund without the same focus.

Derivatives risk. Using stock index futures and options and other derivatives can increase fund losses and reduce opportunities for gains when market prices, interest rates or the derivative instruments themselves behave in a way not anticipated by the fund. Using derivatives may increase the volatility of the fund's net asset value and may not provide the result intended. Derivatives may have a leveraging effect on the fund. Some derivatives have the potential for unlimited loss, regardless of the size of the fund’s initial investment. Changes in a derivative’s value may not correlate well with the referenced asset or metric. The fund also may have to sell assets at inopportune times to satisfy its obligations. Derivatives may be difficult to sell, unwind or value, and the counterparty may default on its obligations to the fund. The U.S. government is in the process of adopting and implementing regulations governing derivatives markets, including mandatory clearing of certain derivatives, margin and reporting requirements. The ultimate impact of the regulations remains

Summary Prospectus

unclear. Additional regulation of derivatives may make them more costly, may limit their availability, may disrupt markets or may otherwise adversely affect their value or performance.

Leveraging risk. The value of your investment may be more volatile and other risks tend to be compounded if the fund borrows or uses derivatives or other investments, such as ETFs, that have embedded leverage. Leverage generally magnifies the effect of any increase or decrease in the value of the fund's underlying assets and creates a risk of loss of value on a larger pool of assets than the fund would otherwise have, potentially resulting in the loss of all assets. Engaging in such transactions may cause the fund to liquidate positions when it may not be advantageous to do so to satisfy its obligations or meet segregation requirements.

Valuation risk. The sales price the fund could receive for any particular portfolio investment may differ from the fund’s last valuation of the investment, particularly for illiquid securities and securities that trade in thin or volatile markets or that are valued using a fair value methodology. Investors who purchase or redeem fund shares on days when the fund is holding fair-valued securities may receive fewer or more shares or lower or higher redemption proceeds than they would have received if the fund had not fair-valued the security or had used a different valuation methodology.

Expense risk. Your actual costs of investing in the fund may be higher than the expenses shown in “Annual fund operating expenses” for a variety of reasons. For example, expense ratios may be higher than those shown if overall net assets decrease. Net assets are more likely to decrease and fund expense ratios are more likely to increase when markets are volatile.

Please note that there are many other factors that could adversely affect your investment and that could prevent the fund from achieving its goals.

An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

The fund's past performance

The bar chart and table indicate the risks and volatility of an investment in the fund by showing how the fund has performed in the past. The bar chart shows changes in the performance of the fund's Class A shares from calendar year to calendar year. The table shows the average annual total returns for each class of the fund over time and compares these returns to

the returns of the Russell 1000 Value Index, a broad-based measure of market performance that has characteristics relevant to the fund’s investment strategies. You can obtain updated performance information by visiting https://us.pioneerinvestments.com/performance or by calling 1-800-225-6292.

The fund's past performance (before and after taxes) does not necessarily indicate how it will perform in the future.

The bar chart does not reflect any sales charge you may pay when you buy fund shares. If this amount was reflected, returns would be less than those shown.

Annual return Class A shares (%)

(Year ended December 31)

For the period covered by the bar chart:

The highest calendar quarterly return was 13.18% (07/01/2009 to 09/30/2009).
The lowest calendar quarterly return was –21.20% (10/01/2008 to 12/31/2008).

Summary Prospectus

Average annual total return (%)

(for periods ended December 31, 2015)

	1 Year	5 Years	10 Years	Since Inception	Inception Date
Class A					7/25/90
Return before taxes	-5.51	9.93	6.26	9.19
Return after taxes on distributions	-7.90	8.24	5.01	7.77
Return after taxes on distributions and sale of shares	-1.71	7.70	4.95	7.46
Class C†	-0.48	10.43	6.09	7.14	1/31/96
Class K	0.64	N/A	N/A	13.29	12/20/12
Class R	-0.11	10.88	6.61	9.00	4/1/03
Class Y	0.51	11.61	7.30	6.42	7/2/98
Russell 1000 Value Index (reflects no deduction for fees, expenses or taxes)	-3.83	11.27	6.16	9.86	7/31/90

†	The performance of Class C shares does not reflect the 1% front-end sales charge in effect prior to February 1, 2004. If you paid a 1% sales charge, your returns would be lower than those shown above.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.

After-tax returns are shown only for Class A shares. After-tax returns for Class C, Class K, Class R and Class Y shares will vary.

Management

Investment adviser	Pioneer Investment Management, Inc.
Portfolio management	John A. Carey, Executive Vice President of Pioneer (portfolio manager of the fund since 1990), and Walter Hunnewell, Jr., Vice President of Pioneer (portfolio manager of the fund since 2001)

Purchase and sale of fund shares

You may purchase, exchange or sell (redeem) shares each day the New York Stock Exchange is open through your financial intermediary or, for accounts held directly with the fund, by contacting the fund in writing or by telephone: Pioneer Funds, P.O. Box 55014, Boston, MA 02205-5014, tel. 1-800-225-6292.

Your initial investment for Class A or Class C shares must be at least $1,000. Additional investments must be at least $100 for Class A shares and $500 for Class C shares. The initial investment for Class K shares and Class Y shares must be at least $5 million. This amount may be invested in one or more of the Pioneer mutual funds that currently offer Class K shares or Class Y shares, as applicable. There is no minimum additional investment amount for Class K or Class Y shares. There is no minimum investment amount for Class R shares.

Tax information

The fund intends to make distributions that may be taxed as ordinary income, qualified dividend income, or capital gains.

Payments to broker-dealers and other financial intermediaries

If you purchase the fund through a broker-dealer or other financial intermediary (such as a bank), the fund and its related companies may pay the intermediary for the sale of fund shares and related services. These payments create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson or investment professional to recommend the fund over another investment. Ask your salesperson or investment professional or visit your financial intermediary’s website for more information.

23437-08-0316