Pioneer Fundamental Growth FundHigh quality focus mitigates downside risk

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Class A: PIGFX Class C: FUNCX Class K: PFGKX Class R: PFGRX Class Y: FUNYX us.pioneerinvestments.com

Overall Morningstar RatingTM

HHHHH Class Y ShareHHHHH Class A Share (LW)HHHHH Class A Share (LA)

LW: Load-Waived LA: Load-Adjusted

(out of 1,524 funds in the Large Growth Category as of 3/31/16)

Benchmark Russell 1000® Growth Index

Portfolio Management

Andrew Acheson, SVPPortfolio Manager• Joined Pioneer in 1999 • Investment experience since 1994

Paul Cloonan, SVP, CFAPortfolio Manager• Joined Pioneer in 1997 • Investment experience since 1994

Symbols/Expense RatioGross Net

A: PIGFX 1.13% 1.09%*

C: FUNCX 1.79% 1.79%

K: PFGKX 0.69% 0.69%

R: PFGRX 1.52% 1.40%*

Y: FUNYX 0.80% 0.80%

* Contractual expense limits currently in effect through 8/1/2016 for Class A and R shares.

Philosophy/ApproachWe believe a portfolio of companies that have sustainable competitive advantages, earn high returns on growth capital, demonstrate consistent growth and sell at a discount to their intrinsic value can outperform the broader market over time with less risk.

• Sustainable competitive advantage – We look for companies with an economic moat, which creates a barrier to the competition and the potential for above average returns.

• High returns on growth capital – Growth capital is capital a company uses to grow its business versus simply maintaining it. A high return on growth capital is an indication that a company is growing profitably and not simply for the sake of growth.

• Consistent growth – A company must not only have a track record of growth, but also must be able to sustain it. We look for an identifiable tailwind, such as increased spending on pharmaceuticals due to an aging population.

Low Volatility with Attractive Risk-Adjusted ReturnsFor growth investors who fear the effects of volatile markets, Pioneer Fundamental Growth Fund offers an attractive track record of risk and reward.

Pioneer Fundamental Growth Fund Risk/Return Profile (as of 3/31/16)

Downside Capture Standard Deviation Sharpe Ratio

3-Year 5-Year 10-Year 3-Year 5-Year 10-Year 3-Year 5-Year 10-Year

Fund Rank 12% 3% 2% 13% 3% 1% 3% 1% 1%

✦ Pioneer Fundamental Growth Fund – Y Shares ✦ Morningstar Large Growth Category Average

Source: Morningstar as of 3/31/16. Past performance is no guarantee of future results. See full performance data on page 2.

Downside Capture is a measure of relative performance versus an index during those quarters when the index had only negative returns. A down market ratio of 90% suggests outperformance of the index by 10% during quarters with negative returns. Standard deviation is a statistical measure of the historical volatility of a portfolio; a lower standard deviation indicates historically less volatility. Sharpe Ratio is a risk-adjusted measure calculated to determine reward per unit of risk. It uses a standard deviation and excess return. The higher the Sharpe Ratio, the better the portfolio’s historical risk-adjusted performance.

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High Exposure to Wide Moat CompaniesThe idea of an economic moat refers to how likely companies are to keep competitors at bay for an extended period.* We believe one of the keys to finding attractive long-term investments is buying companies that seek to stay one step ahead of their competitors. We attempt to capture this characteristic, the strength and sustainability of a firm’s competitive advantage, with the economic moat rating.

The Wide Moat Effect

Our Attributes of Economic Moats

Efficient ScaleWhen a firm enjoys economies of scale in areas like manufacturing, sales and marketing, it can be pretty tough for a competitor to catch up.

Low-Cost ProducerThe ability to produce products or services at a lower cost than competitors is an advantage that is especially potent in commodity industries.

Intangible Assets such as Brand, Patents

Companies can generate above average profits when a brand or the government protects their products or services from competition.

High Customer Switching Costs

If you can make it tough for your customers to use a competitor, it is usually easy to increase prices year after year, which may lead to higher profits.

The Network Effect

This is a relatively rare, but potentially quite potent, source of competitive advantage, and often accrues by the first mover in an emerging technology. Because a network’s value increases as more people use it, the company that created the network can create a massive economic moat.

Source: Morningstar. Data as of 3/31/16. Indices are unmanaged and their returns assume reinvestment of dividends and, unlike mutual fund returns, do not reflect any fees or expenses associated with a mutual fund. It is not possible to invest directly in an index.

* Moat is a perceived competitive advantage that one company has over other companies in the same industry. The wider the moat, the larger and more sustainable the competitive advantage. By having a well-known brand name, pricing power and a large portion of market demand, a company with a wide moat may possess characteris-tics that act as barriers against other companies wanting to enter into the industry.

A Competitive Large Growth Performer

Average Annual Total Returns as of 3/31/16

YTD 1-Year 3-Year 5-Year 10-Year

Y Shares 0.37% 4.29% 14.33% 13.64% 8.95%

A Shares (NAV) 0.26% 4.00% 14.01% 13.28% 8.68%

A Shares (POP) -5.52% -1.97% 11.79% 11.96% 8.04%

Benchmark: Russell 1000® Growth Index 0.74% 2.52% 13.61% 12.38% 8.28%

Morningstar Large Growth Category Average -2.45% -2.37% 11.07% 9.88% 6.63%

Gross expense ratio (A): 1.13%. Net expense ratio (A): 1.09%. Gross expense ratio (Y): 0.80%. Contractual expense waiver for A shares expires 8/1/16.

Call 1-800-225-6292 or visit us.pioneerinvestments.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost.

Class Y shares are not subject to sales charges and are available for limited groups of investors, including institutional investors.

NAV results represent the percent change in net asset value per share. Public Offering Price reflects deduction of maximum 5.75% sales charge.

All results are historical and assume the reinvestment of dividends and capital gains. Performance for periods prior to the inception of Class Y shares (on 4/8/09) reflects the NAV performance of the Fund’s Class A Shares. The performance does not reflect differences in expenses, including the 12b-1 fees applicable to Class A Shares. Since fees for Class A shares are generally higher than those of Class Y, the performance shown for the Class Y shares prior to their inception would have been higher. Other share classes are available for which performance and expenses will differ.

Performance results reflects any applicable expense waivers in effect during the periods shown. Without such waivers, fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information.

Fund Overview | Pioneer Fundamental Growth Fund

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Analysis of Return on Growth Capital Drives Stock SelectionCompanies invest capital to maintain and grow their businesses. While return on capital is useful in assessing current profitability, we believe return on growth capital provides the best insight into future potential growth and profitability.

To illustrate this concept, below is a hypothetical example: ABC Food Trucks

2014 2015• ABC opened in 2014 with four trucks

• Total investment cost of $1.2M, or $300k per truck

• Full year profit was $600k

• Return on capital was 50%, which is the total profit ($600k) divided by the total investment ($1.2M)

• ABC had cash flow to invest in the business because of a high return on capital in 2014

• ABC added one additional truck at a cost of $300k

• Profit from the initial four trucks remained at $600k

• Profit from the fifth truck was $180k, due to prime location

• Full year profit of $780k

• Return on capital was 52%

• Return on growth capital was 60%, which is profit from the fifth truck ($180k) divided by the cost of an additional truck ($300k)

2014 2015Number of Trucks Four Five

Investment per Truck $300,000 $300,000

Total Investment $1,200,000 $1,500,000

Profit (from initial four trucks) $600,000 $600,000

Profit (from the fifth truck) N/A $180,000

Total Profit $600,000 $780,000

Return on Capital 50% 52%

Return on Growth Capital N/A 60%

By generating a high return on growth capital in 2015, we believe ABC Food Trucks can expand at a faster rate in 2016 than it could have if returns were lower. The portfolio management team of Pioneer Fundamental Growth Fund focuses on identifying companies that generate high returns on growth capital, which is a differentiator from other growth funds.

For illustrative purposes only. Not meant to represent an investment of the Fund.

High Conviction ApproachThe Fund currently invests in 39 stocks (as of 3/31/16) that we believe best meet our investment criteria of having a sustainable competitive advantage, high returns on growth capital and consistent growth. We believe this high conviction approach to investing reduces overall risk by avoiding lower quality companies that have a greater likelihood of succumbing to competitive threats or allocating capital unwisely.

The Fund’s lower risk profile is evidenced by a lower standard deviation and downside capture than the Russell 1000® Growth Index and its peer group over 5- and 10-year periods. As part of its risk management strategy, the Fund limits industry weightings to 25% and limits position sizes at purchase.

Fund Overview | Pioneer Fundamental Growth Fund

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Securities offered through Pioneer Funds Distributor, Inc. 60 State Street, Boston, Massachusetts 02109 Underwriter of Pioneer mutual funds, Member SIPC ©2016 Pioneer Investments us.pioneerinvestments.com 28210-09-0416

Fund Overview | Pioneer Fundamental Growth Fund

Highly Rated by Morningstar

Morningstar Ratings 3-Year 5-Year 10-Year

As of 3/31/16 Load-Waived Load-Adjusted Load-Waived Load-Adjusted Load-Waived Load-Adjusted

Pioneer Fundamental Growth Fund – A HHHHH HHH HHHHH HHHHH HHHHH HHHHH

Pioneer Fundamental Growth Fund – Y HHHHH HHHHH HHHHH

Morningstar Rankings Large Cap Growth Funds

1-Year Rank/Fund Universe

3-Year Rank/Fund Universe

5-Year Rank/Fund Universe

10-Year Rank/Fund Universe

Pioneer Fundamental Growth Fund – A 3%(45/1663)

10%(148/1524)

3%(30/1315)

7%(59/937)

Pioneer Fundamental Growth Fund – Y 3%(38/1663)

6%(93/1524)

2%(21/1315)

7%(60/937)

Source: Morningstar

Past performance does not guarantee future results. The Overall Morningstar Rating™ is based on a weighted average of the star ratings assigned to a fund’s three-, five-, and ten-year (as applicable) time periods. Ratings and rankings are based on past performance, which is no guarantee of future results. Please see a prospectus for complete information pertaining to load-waived eligibility (such as large purchases or certain types of group plan participants). Morningstar load-waived ratings are based on the standard Morningstar rating methodology with the exception that they are recalculated without the effects of the front load sales charge. Morningstar proprietary ratings reflect risk-adjusted performance as of 3/31/16. For each fund with at least a three-year history, Morningstar calculates a Morningstar Rating™ based on a Morningstar Risk-Adjusted Return measure that accounts for variation in a fund’s monthly performance (including the effects of sales charges, loads and redemption fees), placing more emphasis on downward variations and rewarding consistent performance. The top 10% of funds in each category receive 5 stars, the next 22.5% receive 4 stars, the next 35% receive 3 stars, the next 22.5% receive 2 stars and the bottom 10% receive 1 star. (Each share class is counted as a fraction of one fund within this scale and rated separately, which may cause slight variations in the distribution percentages.) Ratings are Class A and Y shares only; ratings for other classes will vary.

A Word About Risk

Investing in foreign and/or emerging markets securities involves risks relating to interest rates, currency exchange rates, economic and political conditions. The Fund invests in a limited number of securities and, as a result, the Fund’s performance may be more volatile than the performance of other funds holding more securities. At times, the Fund’s investments may represent industries or industry sectors that are interrelated or have common risks, making it more susceptible to any economic, political, or regulatory developments or other risks affecting those industries and sectors. These risks may increase share price volatility.

The Russell 1000® Growth Index measures the performance of large-cap US growth stocks. Indices are unmanaged and their returns assume reinvestment of dividends and, unlike mutual fund returns, do not reflect any fees or expenses associated with a mutual fund. It is not possible to invest directly in an index. The Morningstar (MSTAR) Large Growth Category Average measures the performance of funds in the large-cap universe. Indices are unmanaged and their returns assume reinvestment of dividends and, unlike mutual fund returns, do not reflect any fees or expenses associated with a mutual fund. It is not possible to invest directly in an index. The following copyright pertains only to the Morningstar information. The Morningstar information contained herein: (1) is proprietary to Morningstar; (2) may not be copied; and (3) is not warranted to be accurate, complete or timely. Neither Morningstar nor its content providers are responsible for any damages or losses arising from any use of this information. © 2016 Morningstar, Inc. All Rights Reserved.

Before investing, consider the product’s investment objectives, risks, charges and expenses. Contact your advisor or Pioneer Investments for a prospectus containing this information. Read it carefully. To obtain a prospectus or summary prospectus and for other information on any Pioneer fund, call 1-800-225-6292 or visit our web site at us.pioneerinvestments.com.

Neither Pioneer, nor its representatives are legal or tax advisors. In addition, Pioneer does not provide advice or recommendations. The investments you choose should correspond to your financial needs, goals and risk tolerance. For assistance in determining your financial situation, please consult an investment professional.