UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM N-CSR CERTIFIED SHAREHOLDER REPORT OF REGISTERED MANAGEMENT INVESTMENT COMPANIES 		Investment Company Act file number 811-01835 Pioneer Series Trust XI (Exact name of registrant as specified in charter) 60 State Street, Boston, MA 02109 (Address of principal executive offices) (ZIP code) Terrence J. Cullen, Amundi Pioneer Asset Management, Inc., 60 State Street, Boston, MA 02109 (Name and address of agent for service) Registrant's telephone number, including area code: (617) 742-7825 Date of fiscal year end: December 31 Date of reporting period: January 1, 2019 through June 30, 2019 Form N-CSR is to be used by management investment companies to file reports with the Commission not later than 10 days after the transmission to stockholders of any report that is required to be transmitted to stockholders under Rule 30e-1 under the Investment Company Act of 1940 (17 CFR 270.30e-1). The Commission may use the information provided on Form N-CSR in its regulatory, disclosure review, inspection, and policymaking roles. A registrant is required to disclose the information specified by Form N-CSR, and the Commission will make this information public. A registrant is not required to respond to the collection of information contained in Form N-CSR unless the Form displays a currently valid Office of Management and Budget ("OMB") control number. Please direct comments concerning the accuracy of the information collection burden estimate and any suggestions for reducing the burden to Secretary, Securities and Exchange Commission, 450 Fifth Street, NW, Washington, DC 20549-0609. The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. ss. 3507. ITEM 1. REPORTS TO STOCKHOLDERS. Pioneer Core Equity Fund -------------------------------------------------------------------------------- Semiannual Report | June 30, 2019 -------------------------------------------------------------------------------- Ticker Symbols: Class A PIOTX Class C PCOTX Class K PCEKX Class R CERPX Class Y PVFYX Beginning in February 2021, as permitted by regulations adopted by the Securities and Exchange Commission, paper copies of the Fund's shareholder reports like this one 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, bank or insurance company. Instead, the reports will be made available on the Fund's website, 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 electronically by contacting your financial intermediary or, if you invest directly with the Fund, by calling 1-800-225-6292. You may elect to receive all future reports in paper free of charge. 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 1-800-225-6292. If you invest through a financial intermediary, you can contact your financial intermediary to request that you continue to receive paper copies of your shareholder reports. Your election to receive reports in paper will apply to all funds held in your account if you invest through your financial intermediary or all funds held within the Pioneer Fund complex if you invest directly. [LOGO] Amundi Pioneer ============== ASSET MANAGEMENT visit us: www.amundipioneer.com/us Table of Contents President's Letter 2 Portfolio Management Discussion 4 Portfolio Summary 10 Prices and Distributions 11 Performance Update 12 Comparing Ongoing Fund Expenses 17 Schedule of Investments 19 Financial Statements 24 Notes to Financial Statements 33 Trustees, Officers and Service Providers 42 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 1 President's Letter Since 1928, active portfolio management based on in-depth, fundamental research, has been the foundation of Amundi Pioneer's investment approach. We believe an active management investment strategy is a prudent approach to investing, especially during periods of market volatility, which can result from any number of risk factors, including slow U.S. economic growth, rising interest rates, and geopolitical factors. Of course, in today's global economy, risk factors extend well beyond U.S. borders. In fact, it's not unusual for political and economic issues on the international front to cause or contribute to volatility in U.S. markets. At Amundi Pioneer, each security under consideration is researched by our team of experienced investment professionals, who communicate directly with the management teams of those companies. At the end of this research process, if we have conviction in a company's business model and management team, and regard the security as a potentially solid investment opportunity, an Amundi Pioneer portfolio manager makes an active decision to invest in that security. The portfolio resulting from these decisions represents an expression of his or her convictions, and strives to balance overall risk and return opportunity. As an example, the Standard & Poor's 500 Index -- the predominant benchmark for many U.S. Large-Cap Core Equity funds -- has 500 stocks. An Amundi Pioneer portfolio manager chooses to invest in only those companies that he or she believes can offer the most attractive opportunities to pursue the fund's investment objective, thus potentially benefiting the fund's shareowners. This process results in a portfolio that does not own all 500 stocks, but a much narrower universe. The same active decision to invest in a company is also applied when we decide to sell a security, either due to changing fundamentals, valuation concerns, or market risks. We apply this active decision-making across all of our equity, fixed-income, and global portfolios. Today, as investors, we have many options. It is our view that active management can serve shareholders well not only when markets are thriving, but also during periods of market volatility and uncertainty, thus making it a compelling investment choice. As you consider the many choices today, we encourage you to work with your financial advisor to develop an overall investment plan that addresses both your short- and long-term goals, and to implement such a plan in a disciplined manner. 2 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 We greatly appreciate the trust you have placed in us and look forward to continuing to serve you in the future. Sincerely, /s/ Lisa M. Jones Lisa M. Jones Head of the Americas, President and CEO of U.S. Amundi Pioneer Asset Management USA, Inc. June 30, 2019 Any information in this shareowner report regarding market or economic trends or the factors influencing the Fund's historical or future performance are statements of opinion as of the date of this report. Past performance is no guarantee of future results. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 3 Portfolio Management Discussion | 6/30/19 In the following interview, Craig D. Sterling discusses the market environment and the factors that influenced the performance of Pioneer Core Equity Fund during the six-month period ended June 30, 2019. Mr. Sterling, Managing Director, Director of Core Equity and Head of Equity Research, U.S., and a portfolio manager at Amundi Pioneer Asset Management, Inc. (Amundi Pioneer), is responsible for the day-to-day management of the Fund's investment portfolio, along with Ashesh "Ace" Savla, Team Leader of U.S. Equity Quantitative Research, a vice president, and a portfolio manager at Amundi Pioneer. Q How did the Fund perform during the six-month period ended June 30, 2019? A Pioneer Core Equity Fund's Class A shares returned 18.77% at net asset value during the six-month period ended June 30, 2019, while the Fund's benchmark, the Standard & Poor's 500 Index (the S&P 500), returned 18.54%. During the same period, the average return of the 1,447 mutual funds in Morningstar's Large Blend Funds category was 17.21%. Q How would you describe the environment for the U.S. stock market in the first six months of 2019? A U.S. equities staged a strong rally during the six-month period. In fact, the Fund's benchmark, the S&P 500, registered its best performance for the first half of a calendar year since 1997, returning more than 18.5% from January 1st through June 30th. Heading into the six-month period, equity markets faced a potentially challenging combination of slowing global economic growth, rising tariffs on both U.S. and Chinese goods due to ongoing trade disputes between the two countries, and uncertainty about the outlook for corporate profits. However, a shift in U.S. Federal Reserve (Fed) interest-rate policy, from tightening throughout 2018 to potentially easing in 2019, far outweighed the other concerns and spurred a market rally. After raising interest rates four times in 2018, the Fed adopted an increasingly dovish tone on monetary policy as the six-month period progressed, fueling expectations that it may reverse course from interest- rate hikes and actually cut rates several times by mid-2020. The expectations represented a stark contrast to the market consensus of late 2018, when investors were anticipating continued Fed interest-rate 4 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 increases through 2019. The 180-degree turn in Fed monetary policy provided a firm underpinning for the equity market, and more than overcame the potential headwinds from the other factors mentioned earlier. Over the first half of 2019, equity markets were positive in every month except for May, when concerns about trade disputes and tariffs reached their apex. Growth stocks outperformed value stocks during the period, as investors were attracted to companies with the ability to generate organic earnings growth independent of broader economic trends. The Russell 1000 Growth Index gained 21.49% in the first half of the year, outpacing the 16.24% return of the Russell 1000 Value Index. Within the S&P 500, all sectors posted positive returns for the six-month period, with information technology leading the way. Health care and energy were the S&P 500's weakest-performing sectors over the period, though the returns of those sectors were also solidly positive. Q What were the most important factors driving the Fund's benchmark-relative performance during the six-month period ended June 30, 2019? A Stock selection was the primary driver of the Fund's positive benchmark- relative returns during the period, led by outperformance in the health care, information technology, and financials sectors. Conversely, the Fund's holdings in communications services, energy, and industrials lagged the performance of the corresponding benchmark sectors. Sector allocations were also a positive for the Fund versus the S&P 500, highlighted by the portfolio's average underweight to the weaker-performing health care sector, and an overweight in consumer discretionary, which was a strong performer over the six months. With regard to individual stocks, strong security selection results in health care stemmed in part from a portfolio position in Laboratory Corporation of America, which bounced back from a weak 2018 and contributed positively to the Fund's benchmark-relative performance for the six-month period. Laboratory Corporation, which we believe is a stable and well- managed company, overcame some short-term difficulties, which led to renewed investor interest during the period. Another positive contributor to the Fund's benchmark-relative returns were shares of Zoetis, a producer of medicine and vaccinations for animals, including house pets and livestock. The stock gained ground during the period after the company posted robust earnings results and increased its market share. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 5 In information technology, the Fund's outperformance of the S&P 500 derived primarily from positions in semiconductor stocks, many of which surged off their late-2018 lows, including Advanced Micro Devices, Micron Technology, and Lam Research. In financials, the Fund's relative returns benefited from the outperformance of Progressive, which continued to evolve as a best-in-breed company in the insurance industry. A position in Discover Financial Services, one of the largest credit card issuers in the world, was another leading contributor to the Fund's benchmark-relative results over the six-month period. We initially invested in the stock when the share price was discounting a deterioration in credit quality that we thought unlikely to materialize at a time of low unemployment and rising wages. We chose to sell the Fund's shares in Discover during the second calendar quarter of 2019, after they reached valuations we no longer saw as compelling. In addition, although the Fund lagged the benchmark's return within industrials, the sector was also home to United Rentals, one of the top contributors to the Fund's overall performance for the six-month period. Q What aspects of the Fund's positioning detracted from benchmark-relative performance during the six-month period ended June 30, 2019? A Lack of portfolio exposure to social-media leader Facebook was the key detractor from the Fund's benchmark-relative performance in both the communication services sector, and overall. During the period, investors seemed willing to look beyond the possibility of regulatory or user backlash against Facebook resulting from privacy issues and anti-competitive behavior. Instead, the market focused on the possible upside from growth in the company's Instagram platform, and potential future revenues from Facebook's recently announced cryptocurrency development. We view other internet media stocks, including Alphabet, as more attractive than Facebook, given that such companies have what we believe to be more viable business models as well as greater potential to create value over the long term. In energy, a key detractor from the Fund's benchmark-relative returns during the period was a position in Halliburton, a large oil-and-gas equipment & services company. We based our investment thesis for Halliburton on the company's strong competitive position in the U.S. market, but some previously low-end competitors proceeded to improve their abilities to offer higher-value solutions. The resulting decline in Halliburton's competitive advantage, combined with weaker-than-expected spending by its target customer base, prompted us to sell the Fund's position. Also in energy, an investment in the high-quality 6 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 exploration-and-production company EOG Resources detracted from the Fund's relative performance, but we chose to maintain the position based on our positive view regarding EOG's longer-term potential. Finally, in industrials, a portfolio position in FedEx was the primary reason for the Fund's performance shortfall versus the S&P 500 within the sector. FedEx has had difficulties integrating its acquisition of the European company DHL, while also disappointing investors with a management turnover as well as rising capital expenditures. Believing our original investment thesis was no longer valid, we exited the Fund's position. Q Did the Fund own any derivative securities during the six-month period ended June 30, 2019? If so, did the investments have a material impact on benchmark-relative results? A No. The Fund did not own any derivatives during the reporting period. Q How would you characterize the Fund's overall positioning during the six-month period ended June 30, 2019, and could you discuss any changes you made to the portfolio? A As the second calendar quarter of 2019 progressed (April through June), we reduced the portfolio's weighting in cyclical (economically sensitive) stocks and rotated into stocks of companies with either more defensive characteristics, or that have featured growth trends largely independent of economic developments and conditions. Given the elevated risks with respect to both economic growth and the equity markets, we believed attractively valued stocks of high-quality companies with secular (versus cyclical) growth potential would experience stronger investor demand. Accordingly, we lowered the Fund's exposure to companies that may be vulnerable to weaker-than-expected capital expenditures, and where we thought stock valuations had gotten ahead of themselves. As part of the shift, we reduced the Fund's weightings in the semiconductor, capital goods, and automotive industries. At the individual company level, we reduced the size of the Fund's positions in Micron Technology and United Rentals, and exited the position in Advanced Micro Devices. We rotated the proceeds of those sales into areas of the market where we saw robust fundamentals, more compelling valuations, and lower economic sensitivity. We increased the Fund's weighting in health care, particularly among large-cap pharmaceuticals and managed-care companies. In making the move, we purposely avoided owning stocks of companies in traditionally defensive sectors such as consumer staples and utilities. We think many stocks in those areas are very expensive, and therefore offer little upside. We also feel that investors may not fully appreciate the higher risks involved with investing in those sectors. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 7 We continued to hold a sizable portfolio weighting in the information technology sector, with a preference for companies leveraged to important growth trends such as cloud computing, software-as-a-service, and digitization. Although tech stocks have done well this year, we believe many remain undervalued relative to the companies' potential growth rates. We also remained bullish on the U.S. consumer sector, especially stocks of companies that we believe may benefit from the home repair and remodeling theme, such as Home Depot. In financials, we believe that scale, brand, and technological capabilities are now driving the banking industry to a larger and larger degree, and that belief forms the basis for the Fund's holdings of Bank of America and JPMorgan Chase. We also like Progressive, the insurer we discussed earlier, as the company appears to have separated itself from its competitors through its durable brand and ability to use technology to help manage risk. Q Do you have any closing thoughts for investors? A While equities registered solid, even spectacular returns in the first half of the calendar year, we think weaker global economic growth trends may feed through into slower corporate earnings growth over the next few quarters. The Fed has communicated its willingness to cut interest rates, which could help stabilize economic activity and give the market greater confidence about the prospects for a "soft landing" of the domestic economy. However, if the Fed fails to act quickly enough -- or if the uncertainty surrounding trade disputes persists for longer than expected -- the resulting risks for the market could be high. In our view, such circumstances may prompt investors to gravitate toward attractively valued stocks of higher quality and more defensive companies with robust underlying business models, high profitability, below-average debt, and secular growth opportunities. We believe our emphasis on holding shares of those types of companies in the Fund's portfolio is well suited to this environment. 8 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 Please refer to the Schedule of Investments on pages 19-23 for a full listing of Fund securities. All investments are subject to risk, including the possible loss of principal. In the past several years, financial markets have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. These conditions may continue, recur, worsen or spread. 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. Investing in foreign and/or emerging markets securities involves risks relating to interest rates, currency exchange rates, economic, and political conditions. These risks may increase share price volatility. Before investing, consider the product's investment objectives, risks, charges and expenses. Contact your advisor or Amundi Pioneer Asset Management, Inc., for a prospectus or summary prospectus containing this information. Read it carefully. Any information in this shareholder report regarding market or economic trends or the factors influencing the Fund's historical or future performance are statements of opinion as of the date of this report. Past performance is no guarantee of future results. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 9 Portfolio Summary | 6/30/19 Sector Distribution -------------------------------------------------------------------------------- (As a percentage of total investments)* Information Technology 21.0% Financials 17.0% Health Care 16.7% Consumer Discretionary 14.4% Communication Services 6.8% Industrials 5.9% Real Estate 4.3% Energy 4.1% Consumer Staples 3.9% Government 3.1% Materials 2.3% Utilities 0.5% 10 Largest Holdings -------------------------------------------------------------------------------- (As a percentage of total investments)* 1. Microsoft Corp. 5.95% -------------------------------------------------------------------------------- 2. Amazon.com, Inc. 5.62 -------------------------------------------------------------------------------- 3. JPMorgan Chase & Co. 4.81 -------------------------------------------------------------------------------- 4. Home Depot, Inc. 4.11 -------------------------------------------------------------------------------- 5. Alphabet, Inc. 3.84 -------------------------------------------------------------------------------- 6. Humana, Inc. 3.00 -------------------------------------------------------------------------------- 7. Progressive Corp. 3.00 -------------------------------------------------------------------------------- 8. Merck & Co., Inc. 2.92 -------------------------------------------------------------------------------- 9. EOG Resources, Inc. 2.91 -------------------------------------------------------------------------------- 10. Bank of America Corp. 2.65 -------------------------------------------------------------------------------- * Excludes temporary cash investments and all derivative contracts except for options purchased. The Fund is actively managed, and current holdings may be different. The holdings listed should not be considered recommendations to buy or sell any securities. 10 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 Prices and Distributions | 6/30/19 Net Asset Value per Share -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Class 6/30/19 12/31/18 -------------------------------------------------------------------------------- A $18.92 $15.93 -------------------------------------------------------------------------------- C $16.35 $13.82 -------------------------------------------------------------------------------- K $18.93 $15.91 -------------------------------------------------------------------------------- R $18.85 $15.90 -------------------------------------------------------------------------------- Y $19.20 $16.14 -------------------------------------------------------------------------------- Distributions per Share: 1/1/19 - 6/30/19 -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Net Investment Short-Term Long-Term Class Income Capital Gains Capital Gains -------------------------------------------------------------------------------- A $ -- $ -- $ -- -------------------------------------------------------------------------------- C $ -- $ -- $ -- -------------------------------------------------------------------------------- K $ -- $ -- $ -- -------------------------------------------------------------------------------- R $ -- $ -- $ -- -------------------------------------------------------------------------------- Y $ -- $ -- $ -- -------------------------------------------------------------------------------- Index Definition -------------------------------------------------------------------------------- The Standard & Poor's 500 Index is an unmanaged, commonly used measure of the broad U.S. stock market. Index returns are calculated monthly, assume reinvestment of dividends and, unlike Fund returns, do not reflect any fees, expenses or sales charges. It is not possible to invest directly in an index. The index defined here pertains to the "Value of $10,000 Investment" and "Value of $5 Million Investment" charts on pages 12-16. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 11 Performance Update | 6/30/19 Class A Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $10,000 investment made in Class A shares of Pioneer Core Equity Fund at public offering price during the periods shown, compared to that of the Standard & Poor's 500 Index. Average Annual Total Returns (As of June 30, 2019) ------------------------------------------------------ Net Public Asset Offering S&P Value Price 500 Period (NAV) (POP) Index ------------------------------------------------------ 10 years 13.10% 12.44% 14.70% 5 years 8.61 7.33 10.71 1 year 5.87 -0.22 10.42 ------------------------------------------------------ Expense Ratio (Per prospectus dated May 1, 2019) ------------------------------------------------------ Gross ------------------------------------------------------ 0.90% ------------------------------------------------------ [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Core Equity Fund S&P 500 Index 6/09 $ 9,425 $10,000 6/10 $10,628 $11,443 6/11 $14,136 $14,955 6/12 $14,713 $15,770 6/13 $17,264 $19,018 6/14 $21,370 $23,698 6/15 $22,465 $25,457 6/16 $21,858 $26,473 6/17 $26,474 $31,211 6/18 $30,498 $35,698 6/19 $32,289 $39,416 Call 1-800-225-6292 or visit www.amundipioneer.com/us 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. NAV results represent the percent change in net asset value per share. NAV returns would have been lower had sales charges been reflected. POP returns reflect deduction of maximum 5.75% sales charge. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect 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. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. The Fund acquired the assets and liabilities of Pioneer Research Fund ("the predecessor fund") on June 7, 2013. As a result of the reorganization, the predecessor fund's performance and financial history became the performance and financial history of the Fund. The performance of Class A shares of the Fund is the performance of Class A shares of the predecessor fund for periods prior to the reorganization, and has not been restated to reflect any differences in expenses. Please refer to the financial highlights for a more current expense ratio. 12 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 Performance Update | 6/30/19 Class C Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $10,000 investment made in Class C shares of Pioneer Core Equity Fund for the periods shown, compared to that of the Standard & Poor's 500 Index. Average Annual Total Returns (As of June 30, 2019) ------------------------------------------------------ S&P If If 500 Period Held Redeemed Index ------------------------------------------------------ 10 years 12.12% 12.12% 14.70% 5 years 7.72 7.72 10.71 1 year 5.05 5.05 10.42 ------------------------------------------------------ Expense Ratio (Per prospectus dated May 1, 2019) ------------------------------------------------------ Gross ------------------------------------------------------ 1.69% ------------------------------------------------------ [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Core Equity Fund S&P 500 Index 6/09 $10,000 $10,000 6/10 $11,173 $11,443 6/11 $14,716 $14,955 6/12 $15,182 $15,770 6/13 $17,638 $19,018 6/14 $21,641 $23,698 6/15 $22,556 $25,457 6/16 $21,781 $26,473 6/17 $26,158 $31,211 6/18 $29,884 $35,698 6/19 $31,394 $39,416 Call 1-800-225-6292 or visit www.amundipioneer.com/us 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 C shares held for less than one year are also subject to a 1% contingent deferred sales charge (CDSC). If you paid a 1% sales charge, your returns would be lower than those shown above. "If Held" results represent the percent change in net asset value per share. NAV returns would have been lower had sales charges been reflected. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect 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. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. The Fund acquired the assets and liabilities of Pioneer Research Fund ("the predecessor fund") on June 7, 2013. As a result of the reorganization, the predecessor fund's performance and financial history became the performance and financial history of the Fund. The performance of Class C shares of the Fund is the performance of Class C shares of the predecessor fund for periods prior to the reorganization, and has not been restated to reflect any differences in expenses. Please refer to the financial highlights for a more current expense ratio. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 13 Performance Update | 6/30/19 Class K Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $5 million investment made in Class K shares of Pioneer Core Equity Fund during the periods shown, compared to that of the Standard & Poor's 500 Index. Average Annual Total Returns (As of June 30, 2019) ------------------------------------------------------ Net Asset S&P Value 500 Period (NAV) Index ------------------------------------------------------ 10 years 13.15% 14.70% 5 years 8.70 10.71 1 year 6.26 10.42 ------------------------------------------------------ Expense Ratio (Per prospectus dated May 1, 2019) ------------------------------------------------------ Gross ------------------------------------------------------ 0.57% ------------------------------------------------------ [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $5 Million Investment Pioneer Core Equity Fund S&P 500 Index 6/09 $ 5,000,000 $ 5,000,000 6/10 $ 5,638,234 $ 5,721,488 6/11 $ 7,499,371 $ 7,477,511 6/12 $ 7,805,054 $ 7,884,886 6/13 $ 9,158,620 $ 9,508,949 6/14 $11,336,645 $11,849,007 6/15 $11,917,993 $12,728,534 6/16 $11,595,838 $13,236,737 6/17 $14,044,540 $15,605,596 6/18 $16,187,162 $17,848,762 6/19 $17,201,284 $19,708,142 Call 1-800-225-6292 or visit www.amundipioneer.com/us 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. The performance shown for Class K shares for the period prior to the commencement of operations of Class K shares on May 4, 2018, is the net asset value performance of the Fund's Class A shares, which has not been restated to reflect any differences in expenses, including Rule 12b-1 fees applicable to Class A shares. Since fees for Class A shares generally are higher than those of Class K shares, the performance of Class K shares prior to their inception would have been higher than the performance shown. For the period beginning May 4, 2018, the actual performance of Class K shares is reflected. Class K shares are not subject to sales charges and are available for limited groups of eligible investors, including institutional investors. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect 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. The Fund acquired the assets and liabilities of Pioneer Research Fund ("the predecessor fund") on June 7, 2013. As a result of the reorganization, the predecessor fund's performance and financial history became the performance and financial history of the Fund. The performance of Class A shares of the Fund is the performance of Class A shares of the predecessor fund for periods prior to the reorganization, and has not been restated to reflect any differences in expenses. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Please refer to the financial highlights for more recent expense ratios. 14 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 Performance Update | 6/30/19 Class R Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $10,000 investment made in Class R shares of Pioneer Core Equity Fund for the periods shown, compared to that of the Standard & Poor's 500 Index. Average Annual Total Returns (As of June 30, 2019) ------------------------------------------------------ Net Asset S&P Value 500 Period (NAV) Index ------------------------------------------------------ 10 years 13.08% 14.70% 5 years 8.55 10.71 1 year 5.61 10.42 ------------------------------------------------------ Expense Ratio (Per prospectus dated May 1, 2019) ------------------------------------------------------ Gross ------------------------------------------------------ 1.06% ------------------------------------------------------ [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Core Equity Fund S&P 500 Index 6/09 $10,000 $10,000 6/10 $11,276 $11,443 6/11 $14,999 $14,955 6/12 $15,610 $15,770 6/13 $18,317 $19,018 6/14 $22,673 $23,698 6/15 $23,836 $25,457 6/16 $23,192 $26,473 6/17 $28,089 $31,211 6/18 $32,359 $35,698 6/19 $34,173 $39,416 Call 1-800-225-6292 or visit www.amundipioneer.com/us 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. The performance shown for Class R shares for the period prior to the commencement of operations of Class R shares on June 29, 2018, is the net asset value performance of the Fund's Class A shares, reduced to reflect the higher distribution and service fees of Class R shares. For the period beginning June 29, 2018, the actual performance of Class R shares is reflected. Class R shares are not subject to sales charges and are available for limited groups of eligible investors, including institutional investors. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect 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. The Fund acquired the assets and liabilities of Pioneer Research Fund ("the predecessor fund") on June 7, 2013. As a result of the reorganization, the predecessor fund's performance and financial history became the performance and financial history of the Fund. The performance of Class A shares of the Fund is the performance of Class A shares of the predecessor fund for periods prior to the reorganization, and has not been restated to reflect any differences in expenses. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Please refer to the financial highlights for more recent expense ratios. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 15 Performance Update | 6/30/19 Class Y Shares Investment Returns -------------------------------------------------------------------------------- The mountain chart on the right shows the change in value of a $5 million investment made in Class Y shares of Pioneer Core Equity Fund during the periods shown, compared to that of the Standard & Poor's 500 Index. Average Annual Total Returns (As of June 30, 2019) ------------------------------------------------------ Net Asset S&P Value 500 Period (NAV) Index ------------------------------------------------------ 10 years 13.40% 14.70% 5 years 8.91 10.71 1 year 6.11 10.42 ------------------------------------------------------ Expense Ratio (Per prospectus dated May 1, 2019) ------------------------------------------------------ Gross ------------------------------------------------------ 0.64% ------------------------------------------------------ [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $5 Million Investment Pioneer Core Equity Fund S&P 500 Index 6/09 $ 5,000,000 $ 5,000,000 6/10 $ 5,651,032 $ 5,721,488 6/11 $ 7,532,567 $ 7,477,511 6/12 $ 7,855,260 $ 7,884,886 6/13 $ 9,240,696 $ 9,508,949 6/14 $11,474,833 $11,849,007 6/15 $12,101,430 $12,728,534 6/16 $11,816,188 $13,236,737 6/17 $14,344,898 $15,605,596 6/18 $16,570,915 $17,848,762 6/19 $17,583,565 $19,708,142 Call 1-800-225-6292 or visit www.amundipioneer.com/us 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. The Fund acquired the assets and liabilities of Pioneer Research Fund ("the predecessor fund") on June 7, 2013. As a result of the reorganization, the predecessor fund's performance and financial history became the performance and financial history of the Fund. The performance of Class Y shares of the Fund is the performance of Class Y shares of the predecessor fund for periods prior to the reorganization, and has not been restated to reflect any differences in expenses. Class Y shares are not subject to sales charges and are available for limited groups of eligible investors, including institutional investors. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ. Performance results reflect 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. The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares. Please refer to the financial highlights for a more current expense ratio. 16 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 Comparing Ongoing Fund Expenses As a shareowner in the Fund, you incur two types of costs: (1) ongoing costs, including management fees, distribution and/or service (12b-1) fees, and other Fund expenses; and (2) transaction costs, including sales charges (loads) on purchase payments. This example is intended to help you understand your ongoing expenses (in dollars) of investing in the Fund and to compare these costs with the ongoing costs of investing in other mutual funds. The example is based on an investment of $1,000 at the beginning of the Fund's latest six-month period and held throughout the six months. Using the Tables -------------------------------------------------------------------------------- Actual Expenses The first table below provides information about actual account values and actual expenses. You may use the information in this table, together with the amount you invested, to estimate the expenses that you paid over the period as follows: (1) Divide your account value by $1,000 Example: an $8,600 account value (divided by) $1,000 = 8.6 (2) Multiply the result in (1) above by the corresponding share class's number in the third row under the heading entitled "Expenses Paid During Period" to estimate the expenses you paid on your account during this period. Expenses Paid on a $1,000 Investment in Pioneer Core Equity Fund Based on actual returns from January 1, 2019, through June 30, 2019. ------------------------------------------------------------------------------------------------ Share Class A C K R Y ------------------------------------------------------------------------------------------------ Beginning Account Value $1,000.00 $1,000.00 $1,000.00 $1,000.00 $1,000.00 on 1/1/19 ------------------------------------------------------------------------------------------------ Ending Account Value $1,187.70 $1,183.10 $1,189.80 $1,185.50 $1,189.60 on 6/30/19 ------------------------------------------------------------------------------------------------ Expenses Paid $4.88 $9.31 $3.04 $6.88 $3.58 During Period* ------------------------------------------------------------------------------------------------ * Expenses are equal to the Fund's annualized expense ratio of 0.90%, 1.72%, 0.56%, 1.27%, and 0.66% for Class A, Class C, Class K, Class R, and Class Y, respectively, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period). Pioneer Core Equity Fund | Semiannual Report | 6/30/19 17 Hypothetical Example for Comparison Purposes The table below provides information about hypothetical account values and hypothetical expenses based on the Fund's actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the Fund's actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the Fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds. Please note that the expenses shown in the tables are meant to highlight your ongoing costs only and do not reflect any transaction costs, such as sales charges (loads) that are charged at the time of the transaction. Therefore, the table below is useful in comparing ongoing costs only and will not help you determine the relative total costs of owning different funds. In addition, if these transaction costs were included, your costs would have been higher. Expenses Paid on a $1,000 Investment in Pioneer Core Equity Fund Based on a hypothetical 5% per year return before expenses, reflecting the period from January 1, 2019, through June 30, 2019. ------------------------------------------------------------------------------------------------ Share Class A C K R Y ------------------------------------------------------------------------------------------------ Beginning Account Value $1,000.00 $1,000.00 $1,000.00 $1,000.00 $1,000.00 on 1/1/19 ------------------------------------------------------------------------------------------------ Ending Account Value $1,020.33 $1,016.27 $1,022.02 $1,018.50 $1,021.52 on 6/30/19 ------------------------------------------------------------------------------------------------ Expenses Paid $4.51 $8.60 $2.81 $6.36 $3.31 During Period* ------------------------------------------------------------------------------------------------ * Expenses are equal to the Fund's annualized expense ratio of 0.90%, 1.72%, 0.56%, 1.27%, and 0.66% for Class A, Class C, Class K, Class R, and Class Y, respectively, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period). 18 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 Schedule of Investments | 6/30/19 (unaudited) -------------------------------------------------------------------------------------------------------------- Shares Value -------------------------------------------------------------------------------------------------------------- UNAFFILIATED ISSUERS -- 98.1% COMMON STOCKS -- 95.0% of Net Assets Aerospace & Defense -- 1.2% 109,649 Raytheon Co. $ 19,065,768 -------------- Total Aerospace & Defense $ 19,065,768 -------------------------------------------------------------------------------------------------------------- Auto Components -- 2.1% 227,358 Aptiv PLC $ 18,377,347 402,191 BorgWarner, Inc. 16,883,978 -------------- Total Auto Components $ 35,261,325 -------------------------------------------------------------------------------------------------------------- Banks -- 8.4% 1,450,639 Bank of America Corp. $ 42,068,531 683,577 JPMorgan Chase & Co. 76,423,909 76,757(a) SVB Financial Group 17,238,855 -------------- Total Banks $ 135,731,295 -------------------------------------------------------------------------------------------------------------- Beverages -- 1.9% 235,166 PepsiCo., Inc. $ 30,837,317 -------------- Total Beverages $ 30,837,317 -------------------------------------------------------------------------------------------------------------- Capital Markets -- 3.0% 36,176 BlackRock, Inc. $ 16,977,397 221,840 Intercontinental Exchange, Inc. 19,064,930 310,872 Morgan Stanley 13,619,302 -------------- Total Capital Markets $ 49,661,629 -------------------------------------------------------------------------------------------------------------- Chemicals -- 1.5% 334,701 Dow, Inc. $ 16,504,106 41,989 Ecolab, Inc. 8,290,308 -------------- Total Chemicals $ 24,794,414 -------------------------------------------------------------------------------------------------------------- Communications Equipment -- 0.6% 36,856(a) Arista Networks, Inc. $ 9,568,555 -------------- Total Communications Equipment $ 9,568,555 -------------------------------------------------------------------------------------------------------------- Containers & Packaging -- 0.7% 169,048 Ball Corp. $ 11,831,670 -------------- Total Containers & Packaging $ 11,831,670 -------------------------------------------------------------------------------------------------------------- Diversified Telecommunication Services -- 2.1% 1,013,892 AT&T, Inc. $ 33,975,521 -------------- Total Diversified Telecommunication Services $ 33,975,521 -------------------------------------------------------------------------------------------------------------- Electric Utilities -- 0.5% 83,292 American Electric Power Co., Inc. $ 7,330,529 -------------- Total Electric Utilities $ 7,330,529 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 19 Schedule of Investments | 6/30/19 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Shares Value -------------------------------------------------------------------------------------------------------------- Electronic Equipment, Instruments & Components -- 2.1% 186,409 Amphenol Corp. $ 17,884,079 139,882 CDW Corp. 15,526,902 -------------- Total Electronic Equipment, Instruments & Components $ 33,410,981 -------------------------------------------------------------------------------------------------------------- Entertainment -- 0.8% 71,337(a) Live Nation Entertainment, Inc. $ 4,726,076 288,674 Viacom, Inc., Class B 8,622,692 -------------- Total Entertainment $ 13,348,768 -------------------------------------------------------------------------------------------------------------- Equity Real Estate Investment Trusts (REITs) -- 4.3% 147,633 Digital Realty Trust, Inc. $ 17,389,691 58,544 Essex Property Trust, Inc. 17,090,750 97,790 Liberty Property Trust 4,893,412 145,628 Prologis, Inc. 11,664,803 113,744 Simon Property Group, Inc. 18,171,741 -------------- Total Equity Real Estate Investment Trusts (REITs) $ 69,210,397 -------------------------------------------------------------------------------------------------------------- Food & Staples Retailing -- 1.6% 67,551 Costco Wholesale Corp. $ 17,851,027 162,099 Walgreens Boots Alliance, Inc. 8,861,952 -------------- Total Food & Staples Retailing $ 26,712,979 -------------------------------------------------------------------------------------------------------------- Health Care Equipment & Supplies -- 2.9% 61,253(a) ABIOMED, Inc. $ 15,955,794 30,534 Cooper Cos., Inc. 10,286,599 164,048 ResMed, Inc. 20,018,777 -------------- Total Health Care Equipment & Supplies $ 46,261,170 -------------------------------------------------------------------------------------------------------------- Health Care Providers & Services -- 5.6% 179,465 Humana, Inc. $ 47,612,065 109,719(a) Laboratory Corp. of America Holdings 18,970,415 96,388 UnitedHealth Group, Inc. 23,519,636 -------------- Total Health Care Providers & Services $ 90,102,116 -------------------------------------------------------------------------------------------------------------- Household Products -- 0.3% 38,904 Procter & Gamble Co. $ 4,265,824 -------------- Total Household Products $ 4,265,824 -------------------------------------------------------------------------------------------------------------- Insurance -- 5.3% 356,620 American International Group, Inc. $ 19,000,714 191,044 Marsh & McLennan Cos., Inc. 19,056,639 595,376 Progressive Corp. 47,588,404 -------------- Total Insurance $ 85,645,757 -------------------------------------------------------------------------------------------------------------- Interactive Media & Services -- 3.8% 56,356(a) Alphabet, Inc. $ 61,022,277 -------------- Total Interactive Media & Services $ 61,022,277 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 20 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 -------------------------------------------------------------------------------------------------------------- Shares Value -------------------------------------------------------------------------------------------------------------- Internet & Direct Marketing Retail -- 6.4% 47,155(a) Amazon.com, Inc. $ 89,294,123 7,451(a) Booking Holdings, Inc. 13,968,464 -------------- Total Internet & Direct Marketing Retail $ 103,262,587 -------------------------------------------------------------------------------------------------------------- IT Services -- 5.2% 142,849 Accenture PLC $ 26,394,210 291,338 Cognizant Technology Solutions Corp. 18,467,916 222,577 Visa, Inc. 38,628,238 -------------- Total IT Services $ 83,490,364 -------------------------------------------------------------------------------------------------------------- Life Sciences Tools & Services -- 0.4% 7,996(a) Mettler-Toledo International, Inc. $ 6,716,640 -------------- Total Life Sciences Tools & Services $ 6,716,640 -------------------------------------------------------------------------------------------------------------- Machinery -- 2.0% 122,830 Stanley Black & Decker, Inc. $ 17,762,447 174,627 Xylem, Inc. 14,605,802 -------------- Total Machinery $ 32,368,249 -------------------------------------------------------------------------------------------------------------- Multiline Retail -- 0.7% 88,271 Dollar General Corp. $ 11,930,708 -------------- Total Multiline Retail $ 11,930,708 -------------------------------------------------------------------------------------------------------------- Oil, Gas & Consumable Fuels -- 4.0% 496,345 EOG Resources, Inc. $ 46,239,500 338,866 TOTAL SA (A.D.R.) 18,905,334 -------------- Total Oil, Gas & Consumable Fuels $ 65,144,834 -------------------------------------------------------------------------------------------------------------- Pharmaceuticals -- 7.5% 338,264 Eli Lilly & Co. $ 37,476,268 553,432 Merck & Co., Inc. 46,405,273 308,714 Novo Nordisk AS (A.D.R.) 15,756,763 192,663 Zoetis, Inc. 21,865,324 -------------- Total Pharmaceuticals $ 121,503,628 -------------------------------------------------------------------------------------------------------------- Road & Rail -- 1.6% 74,112 Kansas City Southern $ 9,028,324 80,791 Norfolk Southern Corp. 16,104,070 -------------- Total Road & Rail $ 25,132,394 -------------------------------------------------------------------------------------------------------------- Semiconductors & Semiconductor Equipment -- 1.4% 58,606 Lam Research Corp. $ 11,008,551 319,895(a) Micron Technology, Inc. 12,344,748 -------------- Total Semiconductors & Semiconductor Equipment $ 23,353,299 -------------------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 21 Schedule of Investments | 6/30/19 (unaudited) (continued) -------------------------------------------------------------------------------------------------------------- Shares Value -------------------------------------------------------------------------------------------------------------- Software -- 8.8% 109,393(a) Adobe, Inc. $ 32,232,647 704,997 Microsoft Corp. 94,441,398 103,634(a) salesforce.com, Inc. 15,724,387 -------------- Total Software $ 142,398,432 -------------------------------------------------------------------------------------------------------------- Specialty Retail -- 4.8% 314,251 Home Depot, Inc. $ 65,354,780 238,971 TJX Cos., Inc. 12,636,787 -------------- Total Specialty Retail $ 77,991,567 -------------------------------------------------------------------------------------------------------------- Technology Hardware, Storage & Peripherals -- 2.5% 124,642 Apple, Inc. $ 24,669,145 258,194 NetApp, Inc. 15,930,570 -------------- Total Technology Hardware, Storage & Peripherals $ 40,599,715 -------------------------------------------------------------------------------------------------------------- Trading Companies & Distributors -- 1.0% 124,613(a) United Rentals, Inc. $ 16,527,422 -------------- Total Trading Companies & Distributors $ 16,527,422 -------------------------------------------------------------------------------------------------------------- TOTAL COMMON STOCKS (Cost $1,303,174,877) $1,538,458,131 -------------------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------------------------------------- Principal Amount USD ($) -------------------------------------------------------------------------------------------------------------- U.S. GOVERNMENT AND AGENCY OBLIGATIONS -- 3.1% of Net Assets 10,000,000(b) U.S. Treasury Bills, 7/2/19 $ 9,999,461 40,000,000(b) U.S. Treasury Bills, 7/16/19 39,965,854 -------------------------------------------------------------------------------------------------------------- TOTAL U.S. GOVERNMENT AND AGENCY OBLIGATIONS (Cost $49,964,317) $ 49,965,315 -------------------------------------------------------------------------------------------------------------- TOTAL INVESTMENTS IN UNAFFILIATED ISSUERS -- 98.1% (Cost $1,353,139,194) $1,588,423,446 -------------------------------------------------------------------------------------------------------------- OTHER ASSETS AND LIABILITIES -- 1.9% $ 30,133,933 -------------------------------------------------------------------------------------------------------------- NET ASSETS -- 100.0% $1,618,557,379 ============================================================================================================== (A.D.R.) American Depositary Receipts. REIT Real Estate Investment Trust. (a) Non-income producing security. (b) Security issued with a zero coupon. Income is recognized through accretion of discount. Purchases and sales of securities (excluding temporary cash investments) for the six months ended June 30, 2019, aggregated $807,914,831 and $948,475,014, respectively. The accompanying notes are an integral part of these financial statements. 22 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 The Fund is permitted to engage in purchase and sale transactions ("cross trades") with certain funds and accounts for which Amundi Pioneer Asset Management, Inc., (the "Adviser") serves as the Fund's investment adviser, as set forth in Rule 17a-7 under the Investment Company Act of 1940, pursuant to procedures adopted by the Board of Trustees. Under these procedures, cross trades are effected at current market prices. During the six months ended June 30, 2019, the Fund did not engage in cross trade activity. At June 30, 2019, the net unrealized appreciation on investments based on cost for federal tax purposes of $1,354,588,892 was as follows: Aggregate gross unrealized appreciation for all investments in which there is an excess of value over tax cost $251,403,662 Aggregate gross unrealized depreciation for all investments in which there is an excess of tax cost over value (17,569,108) ------------ Net unrealized appreciation $233,834,554 ============ Various inputs are used in determining the value of the Fund's investments. These inputs are summarized in the three broad levels below. Level 1 - quoted prices in active markets for identical securities. Level 2 - other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risks, etc.). See Notes to Financial Statements -- Note 1A. Level 3 - significant unobservable inputs (including the Fund's own assumptions in determining fair value of investments). See Notes to Financial Statements -- Note 1A. The following is a summary of the inputs used as of June 30, 2019, in valuing the Fund's investments: ----------------------------------------------------------------------------------------------------------- Level 1 Level 2 Level 3 Total ----------------------------------------------------------------------------------------------------------- Common Stocks $1,538,458,131 $ -- $ -- $1,538,458,131 U.S. Government and Agency Obligations -- 49,965,315 -- 49,965,315 ----------------------------------------------------------------------------------------------------------- Total Investments in Securities $1,538,458,131 $49,965,315 $ -- $1,588,423,446 =========================================================================================================== During the six months ended June 30, 2019, there were no transfers between Levels 1, 2 and 3. The accompanying notes are an integral part of these financial statements. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 23 Statement of Assets and Liabilities | 6/30/19 (unaudited) ASSETS: Investments in unaffiliated issuers, at value (cost $1,353,139,194) $1,588,423,446 Cash 25,577,115 Receivables -- Investment securities sold 4,673,227 Fund shares sold 37,393 Dividends 982,123 Interest 279 Other assets 64,468 ----------------------------------------------------------------------------------------------- Total assets $1,619,758,051 =============================================================================================== LIABILITIES: Payables -- Fund shares repurchased $ 576,106 Administrative fees 40,168 Transfer agent fees 118,582 Shareowner communications expense 17,611 Registration fees 120,008 Professional fees 26,306 Printing expense 10,859 Distributions 45,683 Due to affiliates 168,821 Accrued expenses 76,528 ----------------------------------------------------------------------------------------------- Total liabilities $ 1,200,672 =============================================================================================== NET ASSETS: Paid-in capital $1,381,543,988 Distributable earnings 237,013,391 ----------------------------------------------------------------------------------------------- Net assets $1,618,557,379 =============================================================================================== NET ASSET VALUE PER SHARE: No par value (unlimited number of shares authorized) Class A (based on $1,552,788,827/82,077,879 shares) $ 18.92 Class C (based on $10,388,503/635,483 shares) $ 16.35 Class K (based on $34,698,416/1,833,287 shares) $ 18.93 Class R (based on $79,980/4,243 shares) $ 18.85 Class Y (based on $20,601,653/1,073,252 shares) $ 19.20 MAXIMUM OFFERING PRICE PER SHARE: Class A (based on $18.92 net asset value per share/100%-5.75% maximum sales charge) $ 20.07 =============================================================================================== The accompanying notes are an integral part of these financial statements. 24 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 Statement of Operations (unaudited) For the Six Months Ended 6/30/19 INVESTMENT INCOME: Dividends from unaffiliated issuers (net of foreign taxes withheld $297,475) $14,126,154 Interest from unaffiliated issuers 417,865 ------------------------------------------------------------------------------------------------------- Total investment income $ 14,544,019 ------------------------------------------------------------------------------------------------------- EXPENSES: Management fees $ 3,918,813 Administrative expense 310,130 Transfer agent fees Class A 467,408 Class C 4,893 Class K 30 Class R 48 Class Y 8,995 Distribution fees Class A 1,872,367 Class C 50,926 Class R 194 Shareowner communications expense 181,335 Custodian fees 10,592 Registration fees 37,987 Professional fees 53,795 Printing expense 13,992 Pricing fees 26 Trustees' fees 34,253 Miscellaneous 48,685 ------------------------------------------------------------------------------------------------------- Total expenses $ 7,014,469 ------------------------------------------------------------------------------------------------------- Net investment income $ 7,529,550 ------------------------------------------------------------------------------------------------------- REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS: Net realized gain (loss) on: Investments in unaffiliated issuers $26,823,755 Class actions 145,613 $ 26,969,368 ------------------------------------------------------------------------------------------------------- Change in net unrealized appreciation (depreciation) on: Investments in unaffiliated issuers $230,686,093 ------------------------------------------------------------------------------------------------------- Net realized and unrealized gain (loss) on investments $257,655,461 ------------------------------------------------------------------------------------------------------- Net increase in net assets resulting from operations $265,185,011 ======================================================================================================= The accompanying notes are an integral part of these financial statements. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 25 Statements of Changes in Net Assets ----------------------------------------------------------------------------------------------------- Six Months Ended 6/30/19 Year Ended (unaudited) 12/31/18 ----------------------------------------------------------------------------------------------------- FROM OPERATIONS: Net investment income (loss) $ 7,529,550 $ 14,079,863 Net realized gain (loss) on investments 26,969,368 173,931,495 Change in net unrealized appreciation (depreciation) on investments 230,686,093 (321,835,356) ----------------------------------------------------------------------------------------------------- Net increase (decrease) in net assets resulting from operations $ 265,185,011 $ (133,823,998) ----------------------------------------------------------------------------------------------------- DISTRIBUTIONS TO SHAREOWNERS: Class A ($-- and $3.14 per share, respectively) $ -- $ (233,691,543) Class C ($-- and $3.00 per share, respectively) -- (1,717,954) Class K ($-- and $3.21 per share, respectively) -- (7,608,473) Class R ($-- and $3.16 per share, respectively) -- (7,560) Class Y ($-- and $3.17 per share, respectively) -- (3,167,681) ----------------------------------------------------------------------------------------------------- Total distributions to shareowners $ -- $ (246,193,211) ----------------------------------------------------------------------------------------------------- FROM FUND SHARE TRANSACTIONS: Net proceeds from sales of shares $ 12,800,199 $ 140,655,901 Reinvestment of distributions -- 228,799,836 Cost of shares repurchased (91,684,742) (259,838,454) ----------------------------------------------------------------------------------------------------- Net increase (decrease) in net assets resulting from Fund share transactions $ (78,884,543) $ 109,617,283 ----------------------------------------------------------------------------------------------------- Net increase (decrease) in net assets $ 186,300,468 $ (270,399,926) NET ASSETS: Beginning of period $1,432,256,911 $1,702,656,837 ----------------------------------------------------------------------------------------------------- End of period $1,618,557,379 $1,432,256,911 ===================================================================================================== The accompanying notes are an integral part of these financial statements. 26 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 --------------------------------------------------------------------------------------------------------------- Six Months Six Months Ended Ended 6/30/19 6/30/19 Year Ended Year Ended Shares Amount 12/31/18 12/31/18 (unaudited) (unaudited) Shares Amount --------------------------------------------------------------------------------------------------------------- Class A Shares sold 442,948 $ 7,927,022 1,303,566 $ 26,373,832 Reinvestment of distributions -- -- 12,709,821 224,191,051 Less shares repurchased (3,972,942) (71,749,886) (7,588,320) (156,138,331) --------------------------------------------------------------------------------------------------------------- Net increase (decrease) (3,529,994) $(63,822,864) 6,425,067 $ 94,426,552 =============================================================================================================== Class C Shares sold 33,693 $ 516,439 184,961 $ 3,251,927 Reinvestment of distributions -- -- 107,229 1,638,461 Less shares repurchased (79,605) (1,232,234) (375,379) (6,949,337) --------------------------------------------------------------------------------------------------------------- Net decrease (45,912) $ (715,795) (83,189) $ (2,058,949) =============================================================================================================== Class K Shares sold 89,103 $ 1,576,449 3,470,577 $ 73,585,363 Reinvestment of distributions -- -- 22,127 346,284 Less shares repurchased (879,344) (15,648,282) (869,176) (17,731,891) --------------------------------------------------------------------------------------------------------------- Net increase (decrease) (790,241) $(14,071,833) 2,623,528 $ 56,199,756 =============================================================================================================== Class R Shares sold 3,871 $ 67,852 2,372 $ 50,000 Reinvestment of distributions -- -- 429 7,560 Less shares repurchased (2,429) (45,325) -- -- --------------------------------------------------------------------------------------------------------------- Net increase 1,442 $ 22,527 2,801 $ 57,560 =============================================================================================================== Class Y Shares sold 146,925 $ 2,712,437 1,744,626 $ 37,394,779 Reinvestment of distributions -- -- 146,312 2,616,480 Less shares repurchased (164,275) (3,009,015) (3,626,653) (79,018,895) --------------------------------------------------------------------------------------------------------------- Net decrease (17,350) $ (296,578) (1,735,715) $ (39,007,636) =============================================================================================================== The accompanying notes are an integral part of these financial statements. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 27 Financial Highlights ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year Year Year 6/30/19 Ended Ended Ended Ended Ended (unaudited) 12/31/18 12/31/17 12/31/16* 12/31/15* 12/31/14* ------------------------------------------------------------------------------------------------------------------------------------ Class A Net asset value, beginning of period $ 15.93 $ 20.58 $ 18.01 $ 16.80 $ 17.18 $ 15.70 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.09(a) $ 0.17(a) $ 0.17(a) $ 0.19(a) $ 0.13(a) $ 0.18 Net realized and unrealized gain (loss) on investments 2.90 (1.68) 4.26 1.22 (0.39) 1.46 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ 2.99 $ (1.51) $ 4.43 $ 1.41 $ (0.26) $ 1.64 ------------------------------------------------------------------------------------------------------------------------------------ Distributions to shareowners: Net investment income $ -- $ (0.14) $ (0.16) $ (0.20) $ (0.12) $ (0.16) Net realized gain -- (3.00) (1.70) -- -- -- ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $ -- $ (3.14) $ (1.86) $ (0.20) $ (0.12) $ (0.16) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ 2.99 $ (4.65) $ 2.57 $ 1.21 $ (0.38) $ 1.48 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 18.92 $ 15.93 $ 20.58 $ 18.01 $ 16.80 $ 17.18 ==================================================================================================================================== Total return (b) 18.77%(c) (8.70)%(d) 24.77% 8.39% (1.49)%(e) 10.44% Ratio of net expenses to average net assets (f) 0.90%(g) 0.90% 0.89% 0.94% 0.93% 0.94% Ratio of net investment income (loss) to average net assets 0.95%(g) 0.82% 0.85% 1.15% 0.75% 1.03% Portfolio turnover rate 53%(c) 114% 81% 80% 100% 57% Net assets, end of period (in thousands) $1,552,789 $1,363,460 $1,629,908 $1,436,208 $1,450,815 $1,605,301 ==================================================================================================================================== * The Fund was audited by an independent registered public accounting firm other than Ernst & Young LLP. (a) The per-share data presented above is based on the average shares outstanding for the period presented. (b) Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions, the complete redemption of the investment at net asset value at the end of each period and no sales charges. Total return would be reduced if sales charges were taken into account. (c) Not annualized. (d) If the Fund had not recognized gains in settlement of class action lawsuits during the year ended December 31, 2018, the total return would have been (8.74)%. (e) If the Fund had not recognized gains in settlement of class action lawsuits during the year ended December 31, 2015, the total return would have been (1.55)%. (f) Includes interest expense of 0.00%, 0.00%, 0.00%, 0.00%, 0.00% and 0.00%+, respectively. (g) Annualized. + Amount rounds to less than 0.01%. The accompanying notes are an integral part of these financial statements. 28 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year Year Year 6/30/19 Ended Ended Ended Ended Ended (unaudited) 12/31/18 12/31/17 12/31/16* 12/31/15* 12/31/14* ------------------------------------------------------------------------------------------------------------------------------------ Class C Net asset value, beginning of period $ 13.82 $18.26 $ 16.17 $ 15.11 $ 15.48 $ 14.19 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.01(a) $ 0.00+(a) $ 0.01(a) $ 0.05(a) $ (0.01)(a)(b) $ 0.02 Net realized and unrealized gain (loss) on investments 2.52 (1.44) 3.80 1.10 (0.35) 1.33 ----------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) from investment operations $ 2.53 $(1.44) $ 3.81 $ 1.15 $ (0.36) $ 1.35 ------------------------------------------------------------------------------------------------------------------------------------ Distributions to shareowners: Net investment income $ -- $ -- $ (0.02) $ (0.09) $ (0.01) $ (0.06) Net realized gain -- (3.00) (1.70) -- -- -- ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $ -- $(3.00) $ (1.72) $ (0.09) $ (0.01) $ (0.06) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ 2.53 $(4.44) $ 2.09 $ 1.06 $ (0.37) $ 1.29 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 16.35 $13.82 $ 18.26 $ 16.17 $ 15.11 $ 15.48 ==================================================================================================================================== Total return (c) 18.31%(d) (9.45)%(e) 23.74% 7.58% (2.34)%(f) 9.52% Ratio of net expenses to average net assets (g) 1.72%(h) 1.69% 1.71% 1.76% 1.74% 1.81% Ratio of net investment income (loss) to average net assets 0.14%(h) 0.02% 0.04% 0.33% (0.06)% 0.14% Portfolio turnover rate 53%(d) 114% 81% 80% 100% 57% Net assets, end of period (in thousands) $10,389 $9,416 $13,961 $13,016 $14,106 $13,848 ==================================================================================================================================== * The Fund was audited by an independent registered public accounting firm other than Ernst & Young LLP. (a) The per-share data presented above is based on the average shares outstanding for the period presented. (b) The amount shown for a share outstanding does not correspond with the net investment gain on the Statement of Operations for the period due to timing of the sales and repurchase of sales. (c) Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions, the complete redemption of the investment at net asset value at the end of each period and no sales charges. Total return would be reduced if sales charges were taken into account. (d) Not annualized. (e) If the Fund had not recognized gains in settlement of class action lawsuits during the year ended December 31, 2018, the total return would have been (9.50)%. (f) If the Fund had not recognized gains in settlement of class action lawsuits during the year ended December 31, 2015, the total return would have been (2.40)%. (g) Includes interest expense of 0.00%, 0.00%, 0.00%, 0.00%, 0.00% and 0.00%+, respectively. (h) Annualized. + Amount rounds to less than 0.01%. The accompanying notes are an integral part of these financial statements. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 29 Financial Highlights (continued) ----------------------------------------------------------------------------------------------------------- Six Months Ended 6/30/19 5/4/18* to (unaudited) 12/31/18 ----------------------------------------------------------------------------------------------------------- Class K Net asset value, beginning of period $ 15.91 $ 20.82 ----------------------------------------------------------------------------------------------------------- Increase (decrease) from investment operations: Net investment income (loss) (a) $ 0.12 $ 0.16 Net realized and unrealized gain (loss) on investments 2.90 (1.86) ----------------------------------------------------------------------------------------------------------- Net increase (decrease) from investment operations $ 3.02 $ (1.70) ----------------------------------------------------------------------------------------------------------- Distributions to shareowners: Net investment income $ -- $ (0.21) Net realized gain -- (3.00) ----------------------------------------------------------------------------------------------------------- Total distributions $ -- $ (3.21) ----------------------------------------------------------------------------------------------------------- Net increase (decrease) in net asset value $ 3.02 $ (4.91) ----------------------------------------------------------------------------------------------------------- Net asset value, end of period $ 18.93 $ 15.91 =========================================================================================================== Total return (b) 18.98%(c)(d) (8.47)%(c)(e) Ratio of net expenses to average net assets 0.56%(f) 0.57%(f) Ratio of net investment income (loss) to average net assets 1.31%(f) 1.17%(f) Portfolio turnover rate 53%(c) 114%(c) Net assets, end of period (in thousands) $34,698 $41,733 =========================================================================================================== * Class K shares commenced operations on May 4, 2018. (a) The per-share data presented above is based on the average shares outstanding for the period presented. (b) Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions and the complete redemption of the investment at net asset value at the end of each period. (c) Not annualized. (d) If the Fund had not recognized gains in settlement of class action lawsuits during the six months ended June 30, 2019, the total return would have been 18.92%. (e) If the Fund had not recognized gains in settlement of class action lawsuits during the year ended December 31, 2018, the total return would have been (8.51)%. (f) Annualized. The accompanying notes are an integral part of these financial statements. 30 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 --------------------------------------------------------------------------------------------------------------- Six Months Ended 6/30/19 6/29/18* to (unaudited) 12/31/18 --------------------------------------------------------------------------------------------------------------- Class R Net asset value, beginning of period $15.90 $21.08 --------------------------------------------------------------------------------------------------------------- Increase (decrease) from investment operations: Net investment income (loss) (a) $ 0.05 $ 0.06 Net realized and unrealized gain (loss) on investments 2.90 (2.08) --------------------------------------------------------------------------------------------------------------- Net increase (decrease) from investment operations $ 2.95 $(2.02) --------------------------------------------------------------------------------------------------------------- Distributions to shareowners: Net investment income $ -- $(0.16) Net realized gain -- (3.00) --------------------------------------------------------------------------------------------------------------- Total distributions $ -- $(3.16) --------------------------------------------------------------------------------------------------------------- Net increase (decrease) in net asset value $ 2.95 $(5.18) --------------------------------------------------------------------------------------------------------------- Net asset value, end of period $18.85 $15.90 =============================================================================================================== =Total return (b) 18.55%(c) (8.76)%(c)(d) Ratio of net expenses to average net assets 1.27%(e) 1.06%(e) Ratio of net investment income (loss) to average net assets 0.55%(e) 0.62%(e) Portfolio turnover rate 53%(c) 114%(c) Net assets, end of period (in thousands) $ 80 $ 45 =============================================================================================================== * Class R shares commenced operations on June 29, 2018. (a) The per-share data presented above is based on the average shares outstanding for the period presented. (b) Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions and the complete redemption of the investment at net asset value at the end of each period. (c) Not annualized. (d) If the Fund had not recognized gains in settlement of class action lawsuits during the year ended December 31, 2018, the total return would have been (8.80)%. (e) Annualized. The accompanying notes are an integral part of these financial statements. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 31 Financial Highlights (continued) ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year Year Year 6/30/19 Ended Ended Ended Ended Ended (unaudited) 12/31/18 12/31/17 12/31/16* 12/31/15* 12/31/14* ------------------------------------------------------------------------------------------------------------------------------------ Class Y Net asset value, beginning of period $ 16.14 $ 20.80 $ 18.18 $ 16.95 $ 17.34 $ 15.85 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.11(a) $ 0.22(a) $ 0.22(a) $ 0.25(a) $ 0.19(a) $ 0.20 Net realized and unrealized gain (loss) on investments 2.95 (1.71) 4.32 1.23 (0.40) 1.51 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ 3.06 $ (1.49) $ 4.54 $ 1.48 $ (0.21) $ 1.71 ------------------------------------------------------------------------------------------------------------------------------------ Distributions to shareowners: Net investment income $ -- $ (0.17) $ (0.22) $ (0.25) $ (0.18) $ (0.22) Net realized gain -- (3.00) (1.70) -- -- -- ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $ -- $ (3.17) $ (1.92) $ (0.25) $ (0.18) $ (0.22) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ 3.06 $ (4.66) $ 2.62 $ 1.23 $ (0.39) $ 1.49 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 19.20 $ 16.14 $ 20.80 $ 18.18 $ 16.95 $ 17.34 ==================================================================================================================================== Total return (b) 18.96%(c)(d) (8.53)%(e) 25.10% 8.73% (1.21)%(f) 10.75% Ratio of net expenses to average net assets (g) 0.66%(h) 0.64% 0.63% 0.63% 0.62% 0.63% Ratio of net investment income (loss) to average net assets 1.19%(h) 1.05% 1.11% 1.47% 1.07% 1.37% Portfolio turnover rate 53%(c) 114% 81% 80% 100% 57% Net assets, end of period (in thousands) $20,602 $17,603 $58,788 $44,915 $62,206 $66,424 ==================================================================================================================================== * The Fund was audited by an independent registered public accounting firm other than Ernst & Young LLP. (a) The per-share data presented above is based on the average shares outstanding for the period presented. (b) Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions and the complete redemption of the investment at net asset value at the end of each period. (c) Not annualized. (d) If the Fund had not recognized gains in settlement of class action lawsuits during the six months ended June 30, 2019, the total return would have been 18.90%. (e) If the Fund had not recognized gains in settlement of class action lawsuits during the year ended December 31, 2018, the total return would have been (8.60)%. (f) If the Fund had not recognized gains in settlement of class action lawsuits during the year ended December 31, 2015, the total return would have been (1.27)%. (g) Includes interest expense of 0.00%, 0.00%, 0.00%, 0.00%, 0.00% and 0.00%+, respectively. (h) Annualized. + Amount rounds to less than 0.01%. The accompanying notes are an integral part of these financial statements. 32 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 Notes to Financial Statements | 6/30/19 (unaudited) 1. Organization and Significant Accounting Policies Pioneer Core Equity Fund (the "Fund") is a series of Pioneer Series Trust XI (the "Trust"), a Delaware statutory trust. The Fund is registered under the Investment Company Act of 1940 as a diversified, open-end management investment company. The investment objective of the Fund is to seek long-term capital growth. The Fund offers five classes of shares designated as Class A, Class C, Class K, Class R and Class Y shares. Class K and Class R commenced operations on May 4, 2018, and June 29, 2018, respectively. Each class of shares represents an interest in the same portfolio of investments of the Fund and has identical rights (based on relative net asset values) to assets and liquidation proceeds. Share classes can bear different rates of class-specific fees and expenses, such as transfer agent and distribution fees. Differences in class-specific fees and expenses will result in differences in net investment income and, therefore, the payment of different dividends from net investment income earned by each class. The Amended and Restated Declaration of Trust of the Fund gives the Board of Trustees the flexibility to specify either per-share voting or dollar-weighted voting when submitting matters for shareowner approval. Under per-share voting, each share of a class of the Fund is entitled to one vote. Under dollar-weighted voting, a shareowner's voting power is determined not by the number of shares owned, but by the dollar value of the shares on the record date. Each share class has exclusive voting rights with respect to matters affecting only that class, including with respect to the distribution plan for that class. There is no distribution plan for Class K and Class Y shares. Amundi Pioneer Asset Management, Inc., an indirect, wholly owned subsidiary of Amundi and Amundi's wholly owned subsidiary, Amundi USA, Inc., serves as the Fund's investment adviser (the "Adviser"). Amundi Pioneer Distributor, Inc., an affiliate of Amundi Pioneer Asset Management, Inc., serves as the Fund's distributor (the "Distributor"). In August 2018, the Securities and Exchange Commission ("SEC") released a Disclosure Update and Simplification Final Rule. The Final Rule amends Regulation S-X disclosures requirements to conform them to U.S. Generally Accepted Accounting Principles ("U.S. GAAP") for investment companies. The Fund's financial statements were prepared in compliance with the new amendments to Regulation S-X. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 33 The Fund is an investment company and follows investment company accounting and reporting guidance under U.S. GAAP. U.S. GAAP requires the management of the Fund to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of income, expenses and gain or loss on investments during the reporting period. Actual results could differ from those estimates. The following is a summary of significant accounting policies followed by the Fund in the preparation of its financial statements: A. Security Valuation The net asset value of the Fund is computed once daily, on each day the New York Stock Exchange ("NYSE") is open, as of the close of regular trading on the NYSE. Equity securities that have traded on an exchange are valued by using the last sale price on the principal exchange where they are traded. Equity securities that have not traded on the date of valuation, or securities for which sale prices are not available, generally are valued using the mean between the last bid and asked prices or, if both last bid and asked prices are not available, at the last quoted bid price. Last sale and bid and asked prices are provided by independent third party pricing services. In the case of equity securities not traded on an exchange, prices are typically determined by independent third party pricing services using a variety of techniques and methods. The value of foreign securities is translated into U.S. dollars based on foreign currency exchange rate quotations supplied by a third party pricing source. Trading in non-U.S. equity securities is substantially completed each day at various times prior to the close of the NYSE. The values of such securities used in computing the net asset value of the Fund's shares are determined as of such times. The Fund may use a fair value model developed by an independent pricing service to value non-U.S. equity securities. Fixed-income securities are valued by using prices supplied by independent pricing services, which consider such factors as market prices, market events, quotations from one or more brokers, Treasury spreads, yields, maturities and ratings, or may use a pricing matrix or other fair value methods or techniques to provide an estimated value of the security or instrument. A pricing matrix is a means of valuing a debt security on the basis of current market prices for other debt securities, historical trading patterns in the market for fixed-income securities and/or other factors. Non-U.S. debt securities that are listed on an exchange will be valued at the bid price obtained from an independent third party pricing service. When independent third party 34 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 pricing services are unable to supply prices, or when prices or market quotations are considered to be unreliable, the value of that security may be determined using quotations from one or more broker-dealers. Repurchase agreements are valued at par. Cash may include overnight time deposits at approved financial institutions. Securities for which independent pricing services or broker-dealers are unable to supply prices or for which market prices and/or quotations are not readily available or are considered to be unreliable are valued by a fair valuation team comprised of certain personnel of the Adviser pursuant to procedures adopted by the Fund's Board of Trustees. The Adviser's fair valuation team uses fair value methods approved by the Valuation Committee of the Board of Trustees. The Adviser's fair valuation team is responsible for monitoring developments that may impact fair valued securities and for discussing and assessing fair values on an ongoing basis, and at least quarterly, with the Valuation Committee of the Board of Trustees. Inputs used when applying fair value methods to value a security may include credit ratings, the financial condition of the company, current market conditions and comparable securities. The Fund may use fair value methods if it is determined that a significant event has occurred after the close of the exchange or market on which the security trades and prior to the determination of the Fund's net asset value. Examples of a significant event might include political or economic news, corporate restructurings, natural disasters, terrorist activity or trading halts. Thus, the valuation of the Fund's securities may differ significantly from exchange prices, and such differences could be material. At June 30, 2019, no securities were valued using fair value methods (other than securities valued using prices supplied by independent pricing services, broker-dealers or using a third party insurance industry pricing model). B. Investment Income and Transactions Dividend income is recorded on the ex-dividend date, except that certain dividends from foreign securities where the ex-dividend date may have passed are recorded as soon as the Fund becomes aware of the ex-dividend data in the exercise of reasonable diligence. Interest income, including interest on income-bearing cash accounts, is recorded on the accrual basis. Dividend and interest income are reported net of unrecoverable foreign taxes withheld at the applicable country rates and net of income accrued on defaulted securities. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 35 Interest and dividend income payable by delivery of additional shares is reclassified as PIK (payment-in-kind) income upon receipt and is included in interest and dividend income, respectively. Security transactions are recorded as of trade date. Gains and losses on sales of investments are calculated on the identified cost method for both financial reporting and federal income tax purposes. C. Foreign Currency Translation The books and records of the Fund are maintained in U.S. dollars. Amounts denominated in foreign currencies are translated into U.S. dollars using current exchange rates. Net realized gains and losses on foreign currency transactions, if any, represent, among other things, the net realized gains and losses on foreign currency contracts, disposition of foreign currencies and the difference between the amount of income accrued and the U.S. dollars actually received. Further, the effects of changes in foreign currency exchange rates on investments are not segregated on the Statement of Operations from the effects of changes in the market prices of those securities, but are included with the net realized and unrealized gain or loss on investments. D. Federal Income Taxes It is the Fund's policy to comply with the requirements of the Internal Revenue Code applicable to regulated investment companies and to distribute all of its net taxable income and net realized capital gains, if any, to its shareowners. Therefore, no provision for federal income taxes is required. As of December 31, 2018, the Fund did not accrue any interest or penalties with respect to uncertain tax positions, which, if applicable, would be recorded as an income tax expense on the Statement of Operations. Tax returns filed within the prior three years remain subject to examination by federal and state tax authorities. The amount and character of income and capital gain distributions to shareowners are determined in accordance with federal income tax rules, which may differ from U.S. GAAP. Distributions in excess of net investment income or net realized gains are temporary over distributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes. Capital accounts within the financial statements are adjusted for permanent book/tax differences to reflect tax character, but are not adjusted for temporary differences. 36 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 The tax character of current year distributions payable will be determined at the end of the current taxable year. The tax character of distributions paid during the year ended December 31, 2018 was as follows: -------------------------------------------------------------------------- 2018 -------------------------------------------------------------------------- Distributions paid from: Ordinary income $ 29,689,577 Long-term capital gain 216,503,634 -------------------------------------------------------------------------- Total $246,193,211 ========================================================================== The following shows the components of distributable earnings (losses) on a federal income tax basis at December 31, 2018: -------------------------------------------------------------------------- 2018 -------------------------------------------------------------------------- Distributable earnings: Undistributed ordinary income $ 589,310 Undistributed long-term capital gain 3,014 Current year late year loss (31,912,405) Net unrealized appreciation 3,148,461 -------------------------------------------------------------------------- Total $(28,171,620) ========================================================================== The difference between book basis and tax basis unrealized appreciation is attributable to the tax deferral of losses on wash sales, and tax basis adjustments on other holdings. E. Fund Shares The Fund records sales and repurchases of its shares as of trade date. The Distributor earned $20,618 in underwriting commissions on the sale of Class A shares during the six months ended June 30, 2019. F. Class Allocations Income, common expenses and realized and unrealized gains and losses are calculated at the Fund level and allocated daily to each class of shares based on its respective percentage of adjusted net assets at the beginning of the day. Distribution fees are calculated based on the average daily net asset value attributable to Class A, Class C and Class R shares of the Fund, respectively (see Note 4). Class K and Class Y shares do not pay distribution fees. All expenses and fees paid to the Fund's transfer agent for its services are allocated among the classes of shares based on the number of accounts in each class and the ratable allocation of related out-of-pocket expenses (see Note 3). Pioneer Core Equity Fund | Semiannual Report | 6/30/19 37 Distributions to shareowners are recorded as of the ex-dividend date. Distributions paid by the Fund with respect to each class of shares are calculated in the same manner and at the same time, except that net investment income dividends to Class A, Class C, Class K, Class R and Class Y shares can reflect different transfer agent and distribution expense rates. G. Risks The value 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 rates, lack of liquidity in the bond markets or adverse investor sentiment. In the past several years, financial markets have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. These conditions may continue, recur, worsen or spread. At times, the Fund's investments may represent industries or industry sectors that are interrelated or have common risks, making the Fund more susceptible to any economic, political, or regulatory developments or other risks affecting those industries and sectors. The Fund's investments in foreign markets and countries with limited developing markets may subject the Fund to a greater degree of risk than investments in a developed market. These risks include disruptive political or economic conditions and the imposition of adverse governmental laws or currency exchange restrictions. With the increased use of technologies such as the Internet to conduct business, the Fund is susceptible to operational, information security and related risks. While the Fund's Adviser has established business continuity plans in the event of, and risk management systems to prevent, limit or mitigate, such cyber-attacks, there are inherent limitations in such plans and systems, including the possibility that certain risks have not been identified. Furthermore, the Fund cannot control the cybersecurity plans and systems put in place by service providers to the Fund such as Brown Brothers Harriman & Co., the Fund's custodian and accounting agent, and DST Asset Manager Solutions, Inc., the Fund's transfer agent. In addition, many beneficial owners of Fund shares hold them through accounts at broker-dealers, retirement platforms and other financial market participants over which neither the Fund nor Amundi Pioneer exercises control. Each of these may in turn rely on service providers to them, which are also subject to the risk of cyber-attacks. Cybersecurity failures or breaches at Amundi Pioneer or the Fund's service providers or intermediaries have the ability to cause disruptions and impact business operations, potentially resulting in financial losses, interference with the Fund's ability to calculate its net asset value, impediments to trading, the inability of Fund shareowners to effect 38 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 share purchases, redemptions or exchanges or receive distributions, loss of or unauthorized access to private shareowner information and violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, or additional compliance costs. Such costs and losses may not be covered under any insurance. In addition, maintaining vigilance against cyber-attacks may involve substantial costs over time, and system enhancements may themselves be subject to cyber-attacks. The Fund's prospectus contains unaudited information regarding the Fund's principal risks. Please refer to that document when considering the Fund's principal risks. H. Repurchase Agreements Repurchase agreements are arrangements under which the Fund purchases securities from a broker-dealer or a bank, called the counterparty, upon the agreement of the counterparty to repurchase the securities from the Fund at a later date, and at a specific price, which is typically higher than the purchase price paid by the Fund. The securities purchased serve as the Fund's collateral for the obligation of the counterparty to repurchase the securities. The value of the collateral, including accrued interest, is required to be equal to or in excess of the repurchase price. The collateral for all repurchase agreements is held in safekeeping in the customer-only account of the Fund's custodian or a sub-custodian of the Fund. The Adviser is responsible for determining that the value of the collateral remains at least equal to the repurchase price. In the event of a default by the counterparty, the Fund is entitled to sell the securities, but the Fund may not be able to sell them for the price at which they were purchased, thus causing a loss to the Fund. Additionally, if the counterparty becomes insolvent, there is some risk that the Fund will not have a right to the securities, or the immediate right to sell the securities. As of and for the six months ended June 30, 2019, the Fund had no open repurchase agreements. 2. Management Agreement The Adviser manages the Fund's portfolio. Effective October 1, 2018, management fees are calculated daily at the annual of the Fund's average daily net assets rate of 0.50% of the Fund's average daily net assets up to $5 billion and 0.45% of the Fund's average daily net assets over $5 billion. Prior to October 1, 2018, management fees were calculated daily at the annual rate of 0.50% of the Fund's average daily net assets. For the six months ended June 30, 2019, the effective management fee was equivalent to 0.50% (annualized) of the Fund's average daily net assets. In addition, under the management and administration agreements, certain other services and costs, including accounting, regulatory reporting and insurance premiums, are paid by the Fund as administrative reimbursements. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 39 Included in "Due to affiliates" reflected on the Statement of Assets and Liabilities is $114,533 in management fees, administrative costs and certain other reimbursements payable to the Adviser at June 30, 2019. 3. Transfer Agent DST Asset Manager Solutions, Inc. serves as the transfer agent to the Fund at negotiated rates. Transfer agent fees and payables shown on the Statement of Operations and the Statement of Assets and Liabilities, respectively, include sub-transfer agent expenses incurred through the Fund's omnibus relationship contracts. In addition, the Fund reimbursed the transfer agent for out-of-pocket expenses incurred by the transfer agent related to shareowner communications activities such as proxy and statement mailings, and outgoing phone calls. For the six months ended June 30, 2019, such out-of-pocket expenses by class of shares were as follows: -------------------------------------------------------------------------------- Shareowner Communications: -------------------------------------------------------------------------------- Class A $178,180 Class C 2,806 Class K 9 Class R 32 Class Y 308 -------------------------------------------------------------------------------- Total $181,335 ================================================================================ 4. Distribution and Service Plans The Fund has adopted a distribution plan (the "Plan") pursuant to Rule 12b-1 of the Investment Company Act of 1940 with respect to its Class A, Class C and Class R shares. Pursuant to the Plan, the Fund pays the Distributor 0.25% of the average daily net assets attributable to Class A shares as compensation for personal services and/or account maintenance services or distribution services with regard to Class A shares. Pursuant to the Plan, the Fund also pays the Distributor 1.00% of the average daily net assets attributable to Class C shares. The fee for Class C shares consists of a 0.25% service fee and a 0.75% distribution fee paid as compensation for personal services and/or account maintenance services or distribution services with regard to Class C shares. Included in "Due to affiliates" reflected on the Statement of Assets and Liabilities is $54,288 in distribution fees payable to the Distributor at June 30, 2019. The Fund also has adopted a separate service plan for Class R shares (the "Service Plan"). The Service Plan authorizes the Fund to pay securities dealers, plan administrators or other service organizations that agree to provide certain 40 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 services to retirement plans or plan participants holding shares of the Fund a service fee of up to 0.25% of the Fund's average daily net assets attributable to Class R shares held by such plans. In addition, redemptions of Class A, and Class C shares may be subject to a contingent deferred sales charge ("CDSC"). A CDSC of 1.00% may be imposed on redemptions of certain net asset value purchases of Class A shares within 12 months of purchase. Redemptions of Class C shares within 12 months of purchase are subject to a CDSC of 1.00%, based on the lower of cost or market value of shares being redeemed. Shares purchased as part of an exchange remain subject to any CDSC that applied to the original purchase of those shares. There are no CDSCs for Class K, Class R and Class Y shares. Proceeds from the CDSCs are paid to the Distributor. For the six months ended June 30, 2019, CDSCs in the amount of $371 were paid to the Distributor. 5. Line of Credit Facility The Fund, along with certain other funds in the Pioneer Family of Funds (the "Funds"), participates in a committed, unsecured revolving line of credit facility. Borrowings are used solely for temporary or emergency purposes. The Fund may borrow up to the lesser of the amount available under the facility or the limits set for borrowing by the Fund's prospectus and the 1940 Act. Effective August 1, 2018, the Fund participates in a credit facility in the amount of $250 million. Under such facility, depending on the type of loan, interest on borrowings is payable at the London Interbank Offered Rate ("LIBOR") plus 0.90% on an annualized basis, or the Alternate Base Rate, which is the greater of (a) the facility's administrative agent's daily announced prime rate on the borrowing date, (b) 2% plus the Federal Funds Rate on the borrowing date, or (c) 2% plus the overnight Eurodollar rate on the borrowing date. The Funds pay an annual commitment fee to participate in a credit facility. The commitment fee is allocated among participating Funds based on an allocation schedule set forth in the credit agreement. For the six months ended June 30, 2019 the Fund had no borrowings under the credit facility. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 41 Trustees, Officers and Service Providers Trustees Officers Thomas J. Perna, Chairman Lisa M. Jones, President and David R. Bock Chief Executive Officer Diane Durnin Mark E. Bradley, Treasurer and Benjamin M. Friedman Chief Financial and Margaret B.W. Graham Accounting Officer Lisa M. Jones Christopher J. Kelley, Secretary and Lorraine H. Monchak Chief Legal Officer Marguerite A. Piret Fred J. Ricciardi Kenneth J. Taubes Investment Adviser and Administrator Amundi Pioneer Asset Management, Inc. Custodian and Sub-Administrator Brown Brothers Harriman & Co. Principal Underwriter Amundi Pioneer Distributor, Inc. Legal Counsel Morgan, Lewis & Bockius LLP Transfer Agent DST Asset Manager Solutions, Inc. Proxy Voting Policies and Procedures of the Fund are available without charge, upon request, by calling our toll free number (1-800-225-6292). Information regarding how the Fund voted proxies relating to portfolio securities during the most recent 12-month period ended June 30 is publicly available to shareowners at www.amundipioneer.com/us. This information is also available on the Securities and Exchange Commission's web site at www.sec.gov. 42 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 This page is for your notes. Pioneer Core Equity Fund | Semiannual Report | 6/30/19 43 This page is for your notes. 44 Pioneer Core Equity Fund | Semiannual Report | 6/30/19 How to Contact Amundi Pioneer We are pleased to offer a variety of convenient ways for you to contact us for assistance or information. Call us for: -------------------------------------------------------------------------------- Account Information, including existing accounts, new accounts, prospectuses, applications and service forms 1-800-225-6292 FactFoneSM for automated fund yields, prices, account information and transactions 1-800-225-4321 Retirement plans information 1-800-622-0176 Write to us: -------------------------------------------------------------------------------- Amundi Pioneer P.O. Box 219427 Kansas City, MO 64121-9427 Our toll-free fax 1-800-225-4240 Our internet e-mail address us.askamundipioneer@amundipioneer.com (for general questions about Amundi Pioneer only) Visit our web site: www.amundipioneer.com/us This report must be preceded or accompanied by a prospectus. The Fund files a complete schedule of portfolio holdings with the Securities and Exchange Commission for the first and third quarters of each fiscal year as an exhibit to its reports on Form N-PORT. Shareholders may view the filed Form N-PORT by visiting the Commission's web site at https://www.sec.gov. [LOGO] Amundi Pioneer ============== ASSET MANAGEMENT Amundi Pioneer Asset Management, Inc. 60 State Street Boston, MA 02109 www.amundipioneer.com/us Securities offered through Amundi Pioneer Distributor, Inc. 60 State Street, Boston, MA 02109 Underwriter of Pioneer Mutual Funds, Member SIPC [C] 2019 Amundi Pioneer Asset Management 19408-13-0819 ITEM 2. CODE OF ETHICS. (a) Disclose whether, as of the end of the period covered by the report, the registrant has adopted a code of ethics that applies to the registrant's principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions, regardless of whether these individuals are employed by the registrant or a third party. If the registrant has not adopted such a code of ethics, explain why it has not done so. The registrant has adopted, as of the end of the period covered by this report, a code of ethics that applies to the registrant's principal executive officer, principal financial officer, principal accounting officer and controller. (b) For purposes of this Item, the term "code of ethics" means written standards that are reasonably designed to deter wrongdoing and to promote: (1) Honest and ethical conduct, including the ethical handling of actual or apparent conflicts of interest between personal and professional relationships; (2) Full, fair, accurate, timely, and understandable disclosure in reports and documents that a registrant files with, or submits to, the Commission and in other public communications made by the registrant; (3) Compliance with applicable governmental laws, rules, and regulations; (4) The prompt internal reporting of violations of the code to an appropriate person or persons identified in the code; and (5) Accountability for adherence to the code. (c) The registrant must briefly describe the nature of any amendment, during the period covered by the report, to a provision of its code of ethics that applies to the registrant's principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions, regardless of whether these individuals are employed by the registrant or a third party, and that relates to any element of the code of ethics definition enumerated in paragraph (b) of this Item. The registrant must file a copy of any such amendment as an exhibit pursuant to Item 10(a), unless the registrant has elected to satisfy paragraph (f) of this Item by posting its code of ethics on its website pursuant to paragraph (f)(2) of this Item, or by undertaking to provide its code of ethics to any person without charge, upon request, pursuant to paragraph (f)(3) of this Item. The registrant has made no amendments to the code of ethics during the period covered by this report. (d) If the registrant has, during the period covered by the report, granted a waiver, including an implicit waiver, from a provision of the code of ethics to the registrant's principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions, regardless of whether these individuals are employed by the registrant or a third party, that relates to one or more of the items set forth in paragraph (b) of this Item, the registrant must briefly describe the nature of the waiver, the name of the person to whom the waiver was granted, and the date of the waiver. Not applicable. (e) If the registrant intends to satisfy the disclosure requirement under paragraph (c) or (d) of this Item regarding an amendment to, or a waiver from, a provision of its code of ethics that applies to the registrant's principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions and that relates to any element of the code of ethics definition enumerated in paragraph (b) of this Item by posting such information on its Internet website, disclose the registrant's Internet address and such intention. Not applicable. (f) The registrant must: (1) File with the Commission, pursuant to Item 12(a)(1), a copy of its code of ethics that applies to the registrant's principal executive officer,principal financial officer, principal accounting officer or controller, or persons performing similar functions, as an exhibit to its annual report on this Form N-CSR (see attachment); (2) Post the text of such code of ethics on its Internet website and disclose, in its most recent report on this Form N-CSR, its Internet address and the fact that it has posted such code of ethics on its Internet website; or (3) Undertake in its most recent report on this Form N-CSR to provide to any person without charge, upon request, a copy of such code of ethics and explain the manner in which such request may be made. 	See Item 10(2) ITEM 3. AUDIT COMMITTEE FINANCIAL EXPERT. (a) (1) Disclose that the registrant's board of trustees has determined that the registrant either: (i) Has at least one audit committee financial expert serving on its audit committee; or (ii) Does not have an audit committee financial expert serving on its audit committee. The registrant's Board of Trustees has determined that the registrant has at least one audit committee financial expert. (2) If the registrant provides the disclosure required by paragraph (a)(1)(i) of this Item, it must disclose the name of the audit committee financial expert and whether that person is "independent." In order to be considered "independent" for purposes of this Item, a member of an audit committee may not, other than in his or her capacity as a member of the audit committee, the board of trustees, or any other board committee: (i) Accept directly or indirectly any consulting, advisory, or other compensatory fee from the issuer; or (ii) Be an "interested person" of the investment company as defined in Section 2(a)(19) of the Act (15 U.S.C. 80a-2(a)(19)). Mr. David R. Bock, an independent trustee, is such an audit committee financial expert. (3) If the registrant provides the disclosure required by paragraph (a)(1) (ii) of this Item, it must explain why it does not have an audit committee financial expert. Not applicable. ITEM 4. PRINCIPAL ACCOUNTANT FEES AND SERVICES. (a) Disclose, under the caption AUDIT FEES, the aggregate fees billed for each of the last two fiscal years for professional services rendered by the principal accountant for the audit of the registrant's annual financial statements or services that are normally provided by the accountant in connection with statutory and regulatory filings or engagements for those fiscal years. N/A (b) Disclose, under the caption AUDIT-RELATED FEES, the aggregate fees billed in each of the last two fiscal years for assurance and related services by the principal accountant that are reasonably related to the performance of the audit of the registrant's financial statements and are not reported under paragraph (a) of this Item. Registrants shall describe the nature of the services comprising the fees disclosed under this category. N/A (c) Disclose, under the caption TAX FEES, the aggregate fees billed in each of the last two fiscal years for professional services rendered by the principal accountant for tax compliance, tax advice, and tax planning. Registrants shall describe the nature of the services comprising the fees disclosed under this category. N/A (d) Disclose, under the caption ALL OTHER FEES, the aggregate fees billed in each of the last two fiscal years for products and services provided by the principal accountant, other than the services reported in paragraphs (a) through (c) of this Item. Registrants shall describe the nature of the services comprising the fees disclosed under this category. N/A (e) (1) Disclose the audit committee's pre-approval policies and procedures described in paragraph (c)(7) of Rule 2-01 of Regulation S-X. PIONEER FUNDS APPROVAL OF AUDIT, AUDIT-RELATED, TAX AND OTHER SERVICES PROVIDED BY THE INDEPENDENT AUDITOR SECTION I - POLICY PURPOSE AND APPLICABILITY The Pioneer Funds recognize the importance of maintaining the independence of their outside auditors. Maintaining independence is a shared responsibility involving Amudi Pioneer Asset Management, Inc, the audit committee and the independent auditors. The Funds recognize that a Fund's independent auditors: 1) possess knowledge of the Funds, 2) are able to incorporate certain services into the scope of the audit, thereby avoiding redundant work, cost and disruption of Fund personnel and processes, and 3) have expertise that has value to the Funds. As a result, there are situations where it is desirable to use the Fund's independent auditors for services in addition to the annual audit and where the potential for conflicts of interests are minimal. Consequently, this policy, which is intended to comply with Rule 210.2-01(C)(7), sets forth guidelines and procedures to be followed by the Funds when retaining the independent audit firm to perform audit, audit-related tax and other services under those circumstances, while also maintaining independence. Approval of a service in accordance with this policy for a Fund shall also constitute approval for any other Fund whose pre-approval is required pursuant to Rule 210.2-01(c)(7)(ii). In addition to the procedures set forth in this policy, any non-audit services that may be provided consistently with Rule 210.2-01 may be approved by the Audit Committee itself and any pre-approval that may be waived in accordance with Rule 210.2-01(c)(7)(i)(C) is hereby waived. Selection of a Fund's independent auditors and their compensation shall be determined by the Audit Committee and shall not be subject to this policy. SECTION II - POLICY ---------------- -------------------------------- ------------------------------------------------- SERVICE SERVICE CATEGORY DESCRIPTION SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES CATEGORY ---------------- -------------------------------- ------------------------------------------------- I. AUDIT Services that are directly o Accounting research assistance SERVICES related to performing the o SEC consultation, registration independent audit of the Funds statements, and reporting o Tax accrual related matters o Implementation of new accounting standards o Compliance letters (e.g. rating agency letters) o Regulatory reviews and assistance regarding financial matters o Semi-annual reviews (if requested) o Comfort letters for closed end offerings ---------------- -------------------------------- ------------------------------------------------- II. Services which are not o AICPA attest and agreed-upon procedures AUDIT-RELATED prohibited under Rule o Technology control assessments SERVICES 210.2-01(C)(4) (the "Rule") o Financial reporting control assessments and are related extensions of o Enterprise security architecture the audit services support the assessment audit, or use the knowledge/expertise gained from the audit procedures as a foundation to complete the project. In most cases, if the Audit-Related Services are not performed by the Audit firm, the scope of the Audit Services would likely increase. The Services are typically well-defined and governed by accounting professional standards (AICPA, SEC, etc.) ---------------- -------------------------------- ------------------------------------------------- ------------------------------------- ------------------------------------ AUDIT COMMITTEE APPROVAL POLICY AUDIT COMMITTEE REPORTING POLICY ------------------------------------- ------------------------------------ o "One-time" pre-approval o A summary of all such for the audit period for all services and related fees pre-approved specific service reported at each regularly subcategories. Approval of the scheduled Audit Committee independent auditors as meeting. auditors for a Fund shall constitute pre approval for these services. ------------------------------------- ------------------------------------ o "One-time" pre-approval o A summary of all such for the fund fiscal year within services and related fees a specified dollar limit (including comparison to for all pre-approved specified dollar limits) specific service subcategories reported quarterly. o Specific approval is needed to exceed the pre-approved dollar limit for these services (see general Audit Committee approval policy below for details on obtaining specific approvals) o Specific approval is needed to use the Fund's auditors for Audit-Related Services not denoted as "pre-approved", or to add a specific service subcategory as "pre-approved" ------------------------------------- ------------------------------------ SECTION III - POLICY DETAIL, CONTINUED ----------------------- --------------------------- ----------------------------------------------- SERVICE CATEGORY SERVICE CATEGORY SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES DESCRIPTION ----------------------- --------------------------- ----------------------------------------------- III. TAX SERVICES Services which are not o Tax planning and support prohibited by the Rule, o Tax controversy assistance if an officer of the Fund o Tax compliance, tax returns, excise determines that using the tax returns and support Fund's auditor to provide o Tax opinions these services creates significant synergy in the form of efficiency, minimized disruption, or the ability to maintain a desired level of confidentiality. ----------------------- --------------------------- ----------------------------------------------- ------------------------------------- ------------------------- AUDIT COMMITTEE APPROVAL POLICY AUDIT COMMITTEE REPORTING POLICY ------------------------------------- ------------------------- ------------------------------------- ------------------------- o "One-time" pre-approval o A summary of for the fund fiscal year all such services and within a specified dollar limit related fees 				 (including comparison 			 to specified dollar 			 limits) reported 			 quarterly. o Specific approval is needed to exceed the pre-approved dollar limits for these services (see general Audit Committee approval policy below for details on obtaining specific approvals) o Specific approval is needed to use the Fund's auditors for tax services not denoted as pre-approved, or to add a specific service subcategory as "pre-approved" ------------------------------------- ------------------------- SECTION III - POLICY DETAIL, CONTINUED ----------------------- --------------------------- ----------------------------------------------- SERVICE CATEGORY SERVICE CATEGORY SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES DESCRIPTION ----------------------- --------------------------- ----------------------------------------------- IV. OTHER SERVICES Services which are not o Business Risk Management support prohibited by the Rule, o Other control and regulatory A. SYNERGISTIC, if an officer of the Fund compliance projects UNIQUE QUALIFICATIONS determines that using the Fund's auditor to provide these services creates significant synergy in the form of efficiency, minimized disruption, the ability to maintain a desired level of confidentiality, or where the Fund's auditors posses unique or superior qualifications to provide these services, resulting in superior value and results for the Fund. ----------------------- --------------------------- ----------------------------------------------- --------------------------------------- ------------------------ AUDIT COMMITTEE APPROVAL POLICY AUDIT COMMITTEE REPORTING POLICY ------------------------------------- -------------------------- o "One-time" pre-approval o A summary of for the fund fiscal year within all such services and a specified dollar limit related fees 			 (including comparison 			 to specified dollar 				 limits) reported quarterly. o Specific approval is needed to exceed the pre-approved dollar limits for these services (see general Audit Committee approval policy below for details on obtaining specific approvals) o Specific approval is needed to use the Fund's auditors for "Synergistic" or "Unique Qualifications" Other Services not denoted as pre-approved to the left, or to add a specific service subcategory as "pre-approved" ------------------------------------- -------------------------- SECTION III - POLICY DETAIL, CONTINUED ----------------------- ------------------------- ----------------------------------------------- SERVICE CATEGORY SERVICE CATEGORY SPECIFIC PROHIBITED SERVICE SUBCATEGORIES DESCRIPTION ----------------------- ------------------------- ----------------------------------------------- PROHIBITED SERVICES Services which result 1. Bookkeeping or other services in the auditors losing related to the accounting records or independence status financial statements of the audit under the Rule. client* 2. Financial information systems design and implementation* 3. Appraisal or valuation services, fairness* opinions, or contribution-in-kind reports 4. Actuarial services (i.e., setting actuarial reserves versus actuarial audit work)* 5. Internal audit outsourcing services* 6. Management functions or human resources 7. Broker or dealer, investment advisor, or investment banking services 8. Legal services and expert services unrelated to the audit 9. Any other service that the Public Company Accounting Oversight Board determines, by regulation, is impermissible ----------------------- ------------------------- ----------------------------------------------- ------------------------------------------- ------------------------------ AUDIT COMMITTEE APPROVAL POLICY AUDIT COMMITTEE REPORTING POLICY ------------------------------------------- ------------------------------ o These services are not to be o A summary of all performed with the exception of the(*) services and related services that may be permitted fees reported at each if they would not be subject to audit regularly scheduled procedures at the audit client (as Audit Committee meeting defined in rule 2-01(f)(4)) level will serve as continual the firm providing the service. confirmation that has 				 not provided any restricted services. ------------------------------------------- ------------------------------ -------------------------------------------------------------------------------- GENERAL AUDIT COMMITTEE APPROVAL POLICY: o For all projects, the officers of the Funds and the Fund's auditors will each make an assessment to determine that any proposed projects will not impair independence. o Potential services will be classified into the four non-restricted service categories and the "Approval of Audit, Audit-Related, Tax and Other Services" Policy above will be applied. Any services outside the specific pre-approved service subcategories set forth above must be specifically approved by the Audit Committee. o At least quarterly, the Audit Committee shall review a report summarizing the services by service category, including fees, provided by the Audit firm as set forth in the above policy. -------------------------------------------------------------------------------- (2) Disclose the percentage of services described in each of paragraphs (b) through (d) of this Item that were approved by the audit committee pursuant to paragraph (c)(7)(i)(C) of Rule 2-01 of Regulation S-X. Non-Audit Services N/A (f) If greater than 50 percent, disclose the percentage of hours expended on the principal accountants engagement to audit the registrant's financial statements for the most recent fiscal year that were attributed to work performed by persons other than the principal accountant's full-time, permanent employees. N/A (g) Disclose the aggregate non-audit fees billed by the registrants accountant for services rendered to the registrant, and rendered to the registrants investment adviser (not including any sub-adviser whose role is primarily portfolio management and is subcontracted with or overseen by another investment adviser), and any entity controlling, controlled by, or under common control with the adviser that provides ongoing services to the registrant for each of the last two fiscal years of the registrant. N/A (h) Disclose whether the registrants audit committee of the board of trustees has considered whether the provision of non-audit services that were rendered to the registrants investment adviser (not including any subadviser whose role is primarily portfolio management and is subcontracted with or overseen by another investment adviser), and any entity controlling, controlled by, or under common control with the investment adviser that provides ongoing services to the registrant that were not pre-approved pursuant to paragraph (c)(7)(ii) of Rule 2-01 of Regulation S-X is compatible with maintaining the principal accountant's independence. The Fund's audit committee of the Board of Trustees has considered whether the provision of non-audit services that were rendered to the Affiliates (as defined) that were not pre- approved pursuant to paragraph (c)(7)(ii) of Rule 2-01 of Regulation S-X is compatible with maintaining the principal accountant's independence. ITEM 5. AUDIT COMMITTEE OF LISTED REGISTRANTS (a) If the registrant is a listed issuer as defined in Rule 10A-3 under the Exchange Act (17 CFR 240.10A-3), state whether or not the registrant has a separately-designated standing audit committee established in accordance with Section 3(a)(58)(A) of the Exchange Act (15 U.S.C. 78c(a)(58)(A)). If the registrant has such a committee, however designated, identify each committee member. If the entire board of directors is acting as the registrant's audit committee as specified in Section 3(a)(58)(B) of the Exchange Act (15 U.S.C. 78c(a)(58)(B)), so state. N/A (b) If applicable, provide the disclosure required by Rule 10A-3(d) under the Exchange Act (17 CFR 240.10A-3(d)) regarding an exemption from the listing standards for audit committees. N/A ITEM 6. SCHEDULE OF INVESTMENTS. File Schedule of Investments in securities of unaffiliated issuers as of the close of the reporting period as set forth in 210.1212 of Regulation S-X [17 CFR 210.12-12], unless the schedule is included as part of the report to shareholders filed under Item 1 of this Form. Included in Item 1 ITEM 7. DISCLOSURE OF PROXY VOTING POLICIES AND PROCEDURES FOR CLOSED-END MANAGEMENT INVESTMENT COMPANIES. A closed-end management investment company that is filing an annual report on this Form N-CSR must, unless it invests exclusively in non-voting securities, describe the policies and procedures that it uses to determine how to vote proxies relating to portfolio securities, including the procedures that the company uses when a vote presents a conflict between the interests of its shareholders, on the one hand, and those of the company's investment adviser; principal underwriter; or any affiliated person (as defined in Section 2(a)(3) of the Investment Company Act of 1940 (15 U.S.C. 80a-2(a)(3)) and the rules thereunder) of the company, its investment adviser, or its principal underwriter, on the other. Include any policies and procedures of the company's investment adviser, or any other third party, that the company uses, or that are used on the company's behalf, to determine how to vote proxies relating to portfolio securities. Not applicable to open-end management investment companies. ITEM 8. PORTFOLIO MANAGERS OF CLOSED-END MANAGEMENT INVESTMENT COMPANIES. (a) If the registrant is a closed-end management investment company that is filing an annual report on this Form N-CSR,provide the following information: (1) State the name, title, and length of service of the person or persons employed by or associated with the registrant or an investment adviser of the registrant who are primarily responsible for the day-to-day management of the registrant's portfolio ("Portfolio Manager"). Also state each Portfolio Manager's business experience during the past 5 years. Not applicable to open-end management investment companies. ITEM 9. PURCHASES OF EQUITY SECURITIES BY CLOSED-END MANAGEMENT INVESTMENT COMPANY AND AFFILIATED PURCHASERS. (a) If the registrant is a closed-end management investment company, in the following tabular format, provide the information specified in paragraph (b) of this Item with respect to any purchase made by or on behalf of the registrant or any affiliated purchaser, as defined in Rule 10b-18(a)(3) under the Exchange Act (17 CFR 240.10b-18(a)(3)), of shares or other units of any class of the registrant's equity securities that is registered by the registrant pursuant to Section 12 of the Exchange Act (15 U.S.C. 781). Not applicable to open-end management investment companies. ITEM 10. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS. Describe any material changes to the procedures by which shareholders may recommend nominees to the registrant's board of directors, where those changes were implemented after the registrant last provided disclosure in response to the requirements of Item 407(c)(2)(iv) of Regulation S-R(17 CFR 229.407)(as required by Item 22(b)(15)) of Schedule 14A (17 CFR 240.14a-101), or this Item. There have been no material changes to the procedures by which the shareholders may recommend nominees to the registrant's board of directors since the registrant last provided disclosure in response to the requirements of Item 407(c)(2)(iv) of Regulation S-R of Schedule 14(A) in its definitive proxy statement, or this item. ITEM 11. CONTROLS AND PROCEDURES. (a) Disclose the conclusions of the registrant's principal executive and principal financials officers, or persons performing similar functions, regarding the effectiveness of the registrant's disclosure controls and procedures (as defined in Rule 30a-3(c) under the Act (17 CFR 270.30a-3(c))) as of a date within 90 days of the filing date of the report that includes the disclosure required by this paragraph, based on the evaluation of these controls and procedures required by Rule 30a-3(b) under the Act (17 CFR 270.30(a)-3(b) and Rules 13a-15(b) or 15d-15(b) under the Exchange Act (17 CFR 240.13a-15(b) or 240.15d-15(b)). The registrant's principal executive officer and principal financial officer have concluded that the registrant's disclosure controls and procedures are effective based on the evaluation of these controls and procedures as of a date within 90 days of the filing date of this report. (b) Disclose any change in the registrant's internal control over financial reporting (as defined in Rule 30a-3(d) under the Act (17CFR 270.30a-3(d)) that occured during the second fiscal quarter of the period covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting. There were no significant changes in the registrant's internal control over financial reporting that occurred during the second fiscal quarter of the period covered by this report that have materially affected, or are reasonably likely to materially affect, the registrant's internal control over financial reporting. The registrant's principal executive officer and principal financial officer, however, voluntarily are reporting the following information: In August of 2006 the registrant's investment adviser enhanced its internal procedures for reporting performance information required to be included in prospectuses. Those enhancements involved additional internal controls over the appropriateness of performance data generated for this purpose. Such enhancements were made following an internal review which identified prospectuses relating to certain classes of shares of a limited number of registrants where, inadvertently, performance information not reflecting the deduction of applicable sales charges was included. Those prospectuses were revised, and the revised prospectuses were distributed to shareholders. Item 12. Disclosure of Securities Lending Activities for Closed-End Management Investment Companies. (a) If the registrant is a closed-end management investment company, provide the following dollar amounts of income and compensation related to the securities lending activities of the registrant during its most recent fiscal year: N/A (1) Gross income from securities lending activities; N/A (2) All fees and/or compensation for each of the following securities lending activities and related services: any share of revenue generated by the securities lending program paid to the securities lending agent(s) (revenue split); fees paid for cash collateral management services (including fees deducted from a pooled cash collateral reinvestment vehicle) that are not included in the revenue split; administrative fees that are not included in the revenue split; fees for indemnification that are not included in the revenue split; rebates paid to borrowers; and any other fees relating to the securities lending program that are not included in the revenue split, including a description of those other fees; N/A (3) The aggregate fees/compensation disclosed pursuant to paragraph (2); and N/A (4) Net income from securities lending activities (i.e., the dollar amount in paragraph (1) minus the dollar amount in paragraph (3)). If a fee for a service is included in the revenue split, state that the fee is included in the revenue split. N/A (b) If the registrant is a closed-end management investment company, describe the services provided to the registrant by the securities lending agent in the registrants most recent fiscal year. N/A ITEM 13. EXHIBITS. (a) File the exhibits listed below as part of this Form. Letter or number the exhibits in the sequence indicated. (1) Any code of ethics, or amendment thereto, that is the subject of the disclosure required by Item 2, to the extent that the registrant intends to satisfy the Item 2 requirements through filing of an exhibit. (2) A separate certification for each principal executive officer and principal financial officer of the registrant as required by Rule 30a-2(a) under the Act (17 CFR 270.30a-2(a)) , exactly as set forth below: Filed herewith. SIGNATURES [See General Instruction F] Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized. (Registrant) Pioneer Series Trust XI By (Signature and Title)* /s/ Lisa M. Jones Lisa M. Jones, President & Chief Executive Officer Date August 29, 2019 Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated. By (Signature and Title)* /s/ Lisa M. Jones Lisa M. Jones, President & Chief Executive Officer Date August 29, 2019 By (Signature and Title)* /s/ Mark E. Bradley Mark E. Bradley, Treasurer & Chief Accounting & Financial Officer Date August 29, 2019 * Print the name and title of each signing officer under his or her signature.