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 811-06106 Pioneer Mid Cap Value Fund (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: October 31 Date of reporting period: November 1, 2018 through April 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 Mid Cap Value Fund -------------------------------------------------------------------------------- Semiannual Report | April 30, 2019 -------------------------------------------------------------------------------- Ticker Symbols: Class A PCGRX Class C PCCGX Class K PMCKX Class R PCMRX Class Y PYCGX Beginning in April 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 9 Prices and Distributions 10 Performance Update 11 Comparing Ongoing Fund Expenses 16 Schedule of Investments 18 Financial Statements 24 Notes to Financial Statements 33 Trustees, Officers and Service Providers 41 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 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 visit companies and meet with their management teams. 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 Mid Cap Value Fund | Semiannual Report | 4/30/19 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. April 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 Mid Cap Value Fund | Semiannual Report | 4/30/19 3 Portfolio Management Discussion | 4/30/19 In the following interview, Edward T. "Ned" Shadek, Jr. and Timothy Stanish discuss the factors that affected the performance of Pioneer Mid Cap Value Fund during the six-month period ended April 30, 2019. Mr. Shadek, Senior Vice President, Director of Mid Cap Value, 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, along with Mr. Stanish, a vice president, a portfolio EVA (economic value added) analyst, and a portfolio manager at Amundi Pioneer, and Raymond K. Haddad, a vice president and a portfolio manager at Amundi Pioneer. Q How did the Fund perform during the six-month period ended April 30, 2019? A Pioneer Mid Cap Value Fund's Class A shares returned 8.04% at net asset value during the six-month period ended April 30, 2019, while the Fund's benchmark, the Russell Midcap Value Index (the Russell Index), returned 8.28%. During the same period, the average return of the 412 mutual funds in Morningstar's Mid-Cap Value Funds category was 7.08%. Q How would you describe the investment environment for equities during the six-month period ended April 30, 2019? A The period began in November 2018 amidst a severe market slump that dragged down the performance of both equities and bonds. Several factors, including concerns over trade disputes between the U.S. and its major trading partners -- particularly China -- slowing global economic growth, rising interest rates in the U.S., and lower oil prices, drove the sell-off, which lasted through the end of 2018. In December alone, the Standard & Poor's 500 Index (the S&P 500) returned -9.03% and finished the final quarter of 2018 down by 13.52%. The market quickly bounced back as 2018 turned to 2019, however, as the S&P 500 returned more than 13% for the first quarter. The main catalysts behind the strong performance of domestic equities in the first quarter were signals from the U.S. Federal Reserve (the Fed) that -- after increasing interest rates four times in 2018 -- it likely would "pause" on further rate hikes, and investors' optimism with respect to a resolution of the U.S./China trade dispute. April, the final month of the period, was also a solid one for equities, as the S&P 500 returned more than 4%, for a year-to-date return of more than 18%. 4 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 After losing significant ground during the fourth quarter and finishing 2018 down by more than 12%, mid-cap value stocks, as measured by the Fund's benchmark, the Russell Index, have also rebounded strongly in 2019, returning more than 18% for the first four months of the calendar year. Within the Russell Index, the top-performing sectors over the six-month period were information technology and industrials, up by more than 17% and 15%, respectively. The real estate and utilities sectors also generated double-digit returns for the period. The worst performers in the Russell Index over the six months were energy, down by more than 7%, and communication services, which was also finished in negative territory, at -2.7%. Consumer staples, while positive, was the third-worst performing sector in the Fund's benchmark over the six-month period, returning just 1.2%. Q Which of your investment strategies either contributed to or detracted from the Fund's performance relative to the Russell Index during the six-month period ended April 30, 2019? A The Fund's performance was in line with that of the Russell Index for the six-month period, if slightly behind overall. Asset allocation was a modest positive contributor to the Fund's benchmark-relative performance for the period, while stock selection results were essentially neutral versus the Russell Index. With regard to asset allocation, the portfolio's underweight to the strong-performing real estate sector detracted from the Fund's benchmark-relative performance, as did a slight overweight to energy, which was the Russell Index's worst performer for the six-month period. Meanwhile, underweights to communication services and consumer staples, two of the benchmark's weakest sectors over the period, and an overweight to the very strong information technology sector, aided the Fund's benchmark-relative returns. We had underweighted the Fund to real estate early in the period due to concerns over rising interest rates in the U.S., but rates actually went down as the period progressed and the sector benefited. Real estate is also immune, at least to a certain degree, from the trade concerns and some other macroeconomic issues that often plague other sectors. We drastically reduced the Fund's underweight to the sector as the period progressed. The energy sector has struggled of late, as the market appears to be "down" on many companies in the sector, particularly their business models (high expenditures, fewer returns to shareholders, and lower returns on investments). The Fund's underweight to communication services was due to the fact that we simply have not been able to find good fundamentals in the sector. In consumer staples, meanwhile, we believe valuations are too Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 5 high. Conversely, we continue to find good fundamentals in the information technology sector, and good valuations, which improved even more after the fourth-quarter market sell-off. Individual stocks in the portfolio that detracted from the Fund's benchmark-relative performance during the six-month period included National Oilwell Varco (NOV), Centene, and Jazz Pharmaceuticals. Energy firm NOV is a supplier of offshore drilling equipment. With the energy sector struggling during the period, the market for NOV's products was weak, and the company generated disappointing earnings results. Exploration-and-production companies have become more cost-conscious recently, and that has affected NOV's business. It also does not bode particularly well for the company going forward, and so we sold the stock during the period. Shares of Centene, a multi-line managed health care organization, fell during the period due to political uncertainty about the future of the Affordable Care Act. We sold the Fund's position in Centene due to the current concerns, even though we still like the company. The Fund's position in Jazz Pharmaceuticals was another detractor from benchmark-relative performance during the period. The stock price rose and fell frequently over the six months before finishing down by about 20%. We attribute the decline in share price primarily to the market's perception of Jazz as a "one product" company, as 75% to 80% of Jazz's profits come from its sleep disorder drug franchise. Rhetoric in Washington about reining in prescription drug prices also contributed to the company's struggles over the period. We still own the stock, even though we have reduced the Fund's allocation. We believe Jazz has successfully fought off competition from generic drug makers. It also has a great balance sheet and is taking steps to expand its product portfolio. Individual stocks that contributed positively to the Fund's benchmark-relative returns over the six-month period included Pulte Group, Ingersoll-Rand, and Lam Research. Shares of home construction firm Pulte Group rose as the company beat earnings estimates on positive new orders, rising home-selling prices, and strong profit margins. Pulte's share price also benefited from declining interest rates during the period, which has led to more home refinancings and purchases. The Fund's position in industrial firm Ingersoll-Rand contributed positively to benchmark-relative performance over the period. Ingersoll-Rand has good earnings and end-markets, and is less cyclical than other industrial stocks. The company is in the process of selling off its industrial pumps business to Gardner-Denver, a move that may reduce cyclical exposure even more, given that the industrial pumps industry is more cyclical in nature. Finally, a position in Lam Research contributed positively to the Fund's benchmark-relative returns. 6 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 Lam is an information technology firm that we added to the portfolio during the period, as we took advantage of improved valuations after the fourth-quarter market meltdown. The company makes equipment used by semiconductor chipmakers to test their chips, and it has been generating more revenue from parts and services, which has made Lam a more stable, less cyclical business. It is also a leading company in its industry. Q Did you invest the Fund in any derivative securities during the six-month period ended April 30, 2019? A No, the Fund did not own any derivatives during the period. Q What is your outlook as we head towards the middle of 2019, and how have you positioned the Fund's portfolio as of period-end? A We believe the U.S. economy remains in good shape. Despite the presence of some concerns, such as the U.S./China trade situation, we do not believe we are looking at a recession in the near term. Corporate earnings are still solid and the market has been bidding up shares of the companies we like to own in the portfolio: high-quality companies with good earnings. While we may be closer to the end of the economic cycle than the beginning, and the market landscape is a tad more treacherous than it has been, we also do not believe that stock valuations are too bad. With regard to positioning, we have expanded the number of portfolio holdings, and so the Fund is less concentrated than it used to be. We believe we have constructed a portfolio featuring stocks of high-quality companies with better business models and balance sheets, and stable earnings growth. The Fund now has less exposure to highly cyclical stocks, which we believe is a prudent approach given a more uncertain market environment. While the overall valuation of the stocks in the portfolio is higher than before, we believe the higher quality and more stable nature of the Fund's holdings is worth the extra cost. As noted previously, the Fund is much less underweight to real estate now than at the beginning of the six-month period. The portfolio remains underweight versus the Russell Index to utilities, another "bond proxy" sector, as we believe the valuations there remain too high, and we like real estate investment trusts more than utilities stocks. The Fund's benchmark-relative sector overweights as of period-end included information technology and consumer discretionary. In consumer discretionary, we have been avoiding retailers that have higher exposure to eCommerce risk, and have focused more on stocks of companies like discount retailer Dollar General, which has a lower-income customer base that has tended to utilize online vendors less frequently than other consumers. Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 7 Please refer to the Schedule of Investments on pages 18-23 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. Investments in mid-sized companies may offer the potential for higher returns, but are also subject to greater short-term price fluctuations than larger, more established companies. Investing in foreign and/or emerging markets securities involves risks relating to interest rates, currency exchange rates, economic, and political conditions. The portfolio invests in REIT securities, the value of which can fall for a variety of reasons, such as declines in rental income, fluctuating interest rates, poor property management, environmental liabilities, uninsured damage, increased competition, or changes in real estate tax laws. When interest rates rise, the prices of fixed income securities in the fund will generally fall. Conversely, when interest rates fall, the prices of fixed income securities in the Fund will generally rise. At times, the Fund's investments may represent industries or industry sectors that are interrelated or have common risks, making it more susceptible to any economic, political, or regulatory developments or other risks affecting those industries and sectors. These risks may increase share price volatility. 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. 8 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 Portfolio Summary | 4/30/19 Sector Distribution -------------------------------------------------------------------------------- (As a percentage of total investments)* [THE FOLLOWING DATA WAS REPRESENTED AS A PIE CHART IN THE PRINTED MATERIAL] Financials 19.6% Consumer Discretionary 14.1% Information Technology 12.3% Real Estate 12.2% Industrials 12.0% Health Care 8.5% Materials 6.1% Energy 5.6% Utilities 5.1% Government 2.7% Consumer Staples 1.8% 10 Largest Holdings -------------------------------------------------------------------------------- (As a percentage of total investments)* 1. Ingersoll-Rand Plc 2.95% -------------------------------------------------------------------------------- 2. Entergy Corp. 2.55 -------------------------------------------------------------------------------- 3. Public Service Enterprise Group, Inc. 2.51 -------------------------------------------------------------------------------- 4. Dollar General Corp. 2.29 -------------------------------------------------------------------------------- 5. CDW Corp. 2.12 -------------------------------------------------------------------------------- 6. Discover Financial Services 2.11 -------------------------------------------------------------------------------- 7. SVB Financial Group 2.00 -------------------------------------------------------------------------------- 8. Sun Communities, Inc. 1.98 -------------------------------------------------------------------------------- 9. Park Hotels & Resorts, Inc. 1.89 -------------------------------------------------------------------------------- 10. Lincoln National Corp. 1.87 -------------------------------------------------------------------------------- * 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. Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 9 Prices and Distributions | 4/30/19 Net Asset Value per Share -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Class 4/30/19 10/31/18 -------------------------------------------------------------------------------- A $21.88 $22.50 -------------------------------------------------------------------------------- C $14.48 $15.53 -------------------------------------------------------------------------------- K $21.89 $22.56 -------------------------------------------------------------------------------- R $21.35 $21.94 -------------------------------------------------------------------------------- Y $23.74 $24.26 -------------------------------------------------------------------------------- Distributions per Share: 11/1/18-4/30/19 -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Net Investment Short-Term Long-Term Class Income Capital Gains Capital Gains -------------------------------------------------------------------------------- A $0.1755 $ -- $2.0931 -------------------------------------------------------------------------------- C $ -- $ -- $2.0931 -------------------------------------------------------------------------------- K $0.2539 $ -- $2.0931 -------------------------------------------------------------------------------- R $0.0691 $ -- $2.0931 -------------------------------------------------------------------------------- Y $0.2283 $ -- $2.0931 -------------------------------------------------------------------------------- The Russell Midcap Value Index is an unmanaged index that measures the performance of U.S. mid-cap value stocks. 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 11-15. 10 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 Performance Update | 4/30/19 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 Mid Cap Value Fund at public offering price during the periods shown, compared to that of the Russell Midcap Value Index. Average Annual Total Returns (As of April 30, 2019) ----------------------------------------------- Net Public Russell Asset Offering Midcap Value Price Value Period (NAV) (POP) Index ----------------------------------------------- 10 years 10.74% 10.08% 14.98% 5 years 5.18 3.94 7.83 1 year 1.33 -4.49 5.76 ----------------------------------------------- Expense Ratio (Per prospectus dated March 1, 2019) ----------------------------------------------- Gross ----------------------------------------------- 1.02% ----------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Mid Cap Russell Midcap Value Fund Value Index 4/09 $ 9,425 $10,000 4/10 $13,168 $15,439 4/11 $15,217 $18,502 4/12 $14,521 $18,352 4/13 $16,093 $22,695 4/14 $20,301 $27,709 4/15 $21,820 $30,472 4/16 $21,004 $30,418 4/17 $24,726 $35,746 4/18 $25,790 $38,187 4/19 $26,134 $40,386 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. POP returns reflect deduction of maximum 5.75% sales charge. 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. Please refer to the financial highlights for a more current expense ratio. Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 11 Performance Update | 4/30/19 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 Mid Cap Value Fund during the periods shown, compared to that of the Russell Midcap Value Index. Average Annual Total Returns (As of April 30, 2019) ----------------------------------------------- Russell Midcap If If Value Period Held Redeemed Index ----------------------------------------------- 10 years 9.79% 9.79% 14.98% 5 years 4.30 4.30 7.83 1 year 0.42 0.42 5.76 ----------------------------------------------- Expense Ratio (Per prospectus dated March 1, 2019) ----------------------------------------------- Gross ----------------------------------------------- 1.83% ----------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Mid Cap Russell Midcap Value Fund Value Index 4/09 $10,000 $10,000 4/10 $13,841 $15,439 4/11 $15,859 $18,502 4/12 $15,000 $18,352 4/13 $16,480 $22,695 4/14 $20,615 $27,709 4/15 $21,969 $30,472 4/16 $20,985 $30,418 4/17 $24,483 $35,746 4/18 $25,337 $38,187 4/19 $25,442 $40,386 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 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. Please refer to the financial highlights for a more current expense ratio. 12 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 Performance Update | 4/30/19 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 Mid Cap Value Fund during the periods shown, compared to that of the Russell Midcap Value Index. Average Annual Total Returns (As of April 30, 2019) ----------------------------------------------- Net Russell Asset Midcap Value Value Period (NAV) Index ----------------------------------------------- 10 years 10.91% 14.98% 5 years 5.50 7.83 1 year 1.66 5.76 ----------------------------------------------- Expense Ratio (Per prospectus dated March 1, 2019) ----------------------------------------------- Gross ----------------------------------------------- 0.68% ----------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $5 Million Investment Pioneer Mid Cap Russell Midcap Value Fund Value Index 4/09 $ 5,000,000 $ 5,000,000 4/10 $ 6,985,803 $ 7,719,536 4/11 $ 8,072,876 $ 9,250,908 4/12 $ 7,703,557 $ 9,175,896 4/13 $ 8,537,591 $11,347,258 4/14 $10,769,829 $13,854,478 4/15 $11,579,817 $15,235,956 4/16 $11,194,815 $15,208,819 4/17 $13,222,845 $17,873,047 4/18 $13,848,840 $19,093,508 4/19 $14,078,135 $20,193,240 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 March 2, 2015, 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 on March 2, 2015, would have been higher than the performance shown. For the period beginning March 2, 2015, 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. 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. Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 13 Performance Update | 4/30/19 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 Mid Cap Value Fund during the periods shown, compared to that of the Russell Midcap Value Index. Average Annual Total Returns (As of April 30, 2019) ----------------------------------------------- Net Russell Asset Midcap Value Value Period (NAV) Index ----------------------------------------------- 10 years 10.34% 14.98% 5 years 4.75 7.83 1 year 0.84 5.76 ----------------------------------------------- Expense Ratio (Per prospectus dated March 1, 2019) ----------------------------------------------- Gross ----------------------------------------------- 1.48% ----------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $10,000 Investment Pioneer Mid Cap Russell Midcap Value Fund Value Index 4/09 $10,000 $10,000 4/10 $13,940 $15,439 4/11 $16,079 $18,502 4/12 $15,286 $18,352 4/13 $16,884 $22,695 4/14 $21,219 $27,709 4/15 $22,734 $30,472 4/16 $21,784 $30,418 4/17 $25,546 $35,746 4/18 $26,536 $38,187 4/19 $26,759 $40,386 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 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 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. 14 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 Performance Update | 4/30/19 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 Mid Cap Value Fund during the periods shown, compared to that of the Russell Midcap Value Index. Average Annual Total Returns (As of April 30, 2019) ----------------------------------------------- Net Russell Asset Midcap Value Value Period (NAV) Index ----------------------------------------------- 10 years 11.10% 14.98% 5 years 5.46 7.83 1 year 1.57 5.76 ----------------------------------------------- Expense Ratio (Per prospectus dated March 1, 2019) ----------------------------------------------- Gross ----------------------------------------------- 0.78% ----------------------------------------------- [THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL] Value of $5 Million Investment Pioneer Mid Cap Russell Midcap Value Fund Value Index 4/09 $ 5,000,000 $ 5,000,000 4/10 $ 7,014,571 $ 7,719,536 4/11 $ 8,138,015 $ 9,250,908 4/12 $ 7,798,725 $ 9,175,896 4/13 $ 8,677,063 $11,347,258 4/14 $10,984,596 $13,854,478 4/15 $11,843,429 $15,235,956 4/16 $11,436,826 $15,208,819 4/17 $13,491,182 $17,873,047 4/18 $14,107,190 $19,093,508 4/19 $14,328,491 $20,193,240 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 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. Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 15 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 Mid Cap Value Fund Based on actual returns from November 1, 2018, through April 30, 2019. ------------------------------------------------------------------------------------------------------ Share Class A C K R Y ------------------------------------------------------------------------------------------------------ Beginning Account $1,000.00 $1,000.00 $1,000.00 $1,000.00 $1,000.00 Value on 11/1/18 ------------------------------------------------------------------------------------------------------ Ending Account $1,080.40 $1,074.60 $1,082.30 $1,077.80 $1,081.40 Value (after expenses) on 4/30/19 ------------------------------------------------------------------------------------------------------ Expenses Paid $ 5.36 $ 10.08 $ 3.46 $ 7.32 $ 4.08 During Period* ------------------------------------------------------------------------------------------------------ * Expenses are equal to the Fund's annualized net expense ratio of 1.04%, 1.96%, 0.67%, 1.42% and 0.79% for Class A, Class C, Class K, Class R and Class Y shares respectively, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period). 16 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 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 Mid Cap Value Fund Based on a hypothetical 5% per year return before expenses, reflecting the period from November 1, 2018, through April 30, 2019. ------------------------------------------------------------------------------------------------------- Share Class A C K R Y ------------------------------------------------------------------------------------------------------- Beginning Account $1,000.00 $1,000.00 $1,000.00 $1,000.00 $1,000.00 Value on 11/1/18 ------------------------------------------------------------------------------------------------------ Ending Account $1,019.64 $1,015.08 $1,021.47 $1,017.75 $1,020.88 Value (after expenses) on 4/30/19 ------------------------------------------------------------------------------------------------------ Expenses Paid $ 5.21 $ 9.79 $ 3.36 $ 7.10 $ 3.96 During Period* ------------------------------------------------------------------------------------------------------ * Expenses are equal to the Fund's annualized net expense ratio of 1.04%, 1.96%, 0.67%, 1.42% and 0.79% for Class A, Class C, Class K, Class R and Class Y shares respectively, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period). Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 17 Schedule of Investments | 4/30/19 (unaudited) ------------------------------------------------------------------------------------------------ Shares Value ------------------------------------------------------------------------------------------------ UNAFFILIATED ISSUERS -- 100.8% COMMON STOCKS -- 98.0% of Net Assets Aerospace & Defense -- 1.6% 54,375 Huntington Ingalls Industries, Inc. $ 12,102,788 ------------- Total Aerospace & Defense $ 12,102,788 ----------------------------------------------------------------------------------------------- Banks -- 6.6% 318,776 Cathay General Bancorp $ 11,727,769 90,788 First Republic Bank 9,589,029 1,010,000 Huntington Bancshares, Inc. 14,059,200 61,909(a) SVB Financial Group 15,583,733 ------------- Total Banks $ 50,959,731 ----------------------------------------------------------------------------------------------- Building Products -- 1.4% 283,853 Masco Corp. $ 11,087,298 ------------- Total Building Products $ 11,087,298 ----------------------------------------------------------------------------------------------- Capital Markets -- 1.7% 141,296 Nasdaq, Inc. $ 13,027,491 ------------- Total Capital Markets $ 13,027,491 ----------------------------------------------------------------------------------------------- Chemicals -- 1.0% 75,100 Celanese Corp. $ 8,102,539 ------------- Total Chemicals $ 8,102,539 ----------------------------------------------------------------------------------------------- Communications Equipment -- 1.4% 75,157 Motorola Solutions, Inc. $ 10,891,001 ------------- Total Communications Equipment $ 10,891,001 ----------------------------------------------------------------------------------------------- Construction Materials -- 0.7% 40,818 Vulcan Materials Co. $ 5,147,558 ------------- Total Construction Materials $ 5,147,558 ----------------------------------------------------------------------------------------------- Consumer Finance -- 2.8% 202,357 Discover Financial Services $ 16,490,072 81,373(a) Green Dot Corp. 5,189,156 ------------- Total Consumer Finance $ 21,679,228 ----------------------------------------------------------------------------------------------- Containers & Packaging -- 3.9% 70,424 Avery Dennison Corp. $ 7,792,416 195,527 Ball Corp. 11,719,888 180,041(a) Berry Global Group, Inc. 10,586,411 ------------- Total Containers & Packaging $ 30,098,715 ----------------------------------------------------------------------------------------------- Electric Utilities -- 2.6% 205,896 Entergy Corp. $ 19,951,322 ------------- Total Electric Utilities $ 19,951,322 ----------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 18 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 ------------------------------------------------------------------------------------------------ Shares Value ------------------------------------------------------------------------------------------------ Electrical Equipment -- 0.4% 21,454 Acuity Brands, Inc. $ 3,139,364 ------------- Total Electrical Equipment $ 3,139,364 ----------------------------------------------------------------------------------------------- Electronic Equipment, Instruments & Components -- 3.0% 156,657 CDW Corp. $ 16,542,979 81,464(a) Keysight Technologies, Inc. 7,089,812 ------------- Total Electronic Equipment, Instruments & Components $ 23,632,791 ----------------------------------------------------------------------------------------------- Equity Real Estate Investment Trusts (REITs) -- 12.3% 218,670 Americold Realty Trust $ 6,999,627 451,131 Duke Realty Corp. 14,039,197 8,518 Equinix, Inc. 3,873,135 92,252 Extra Space Storage, Inc. 9,565,610 228,313 Gaming & Leisure Properties, Inc. 9,219,279 301,729 Invitation Homes, Inc. 7,500,983 71,635 Lamar Advertising Co. 5,922,065 461,345 Park Hotels & Resorts, Inc. 14,799,947 125,631 Sun Communities, Inc. 15,462,663 347,046 VICI Properties, Inc. 7,912,649 ------------- Total Equity Real Estate Investment Trusts (REITs) $ 95,295,155 ----------------------------------------------------------------------------------------------- Food & Staples Retailing -- 0.7% 79,740 Sysco Corp. $ 5,611,304 ------------- Total Food & Staples Retailing $ 5,611,304 ----------------------------------------------------------------------------------------------- Food Products -- 1.1% 75,084(a) Post Holdings, Inc. $ 8,467,974 ------------- Total Food Products $ 8,467,974 ----------------------------------------------------------------------------------------------- Health Care Equipment & Supplies -- 3.5% 30,084 Cooper Cos., Inc. $ 8,721,953 276,969(a) Hologic, Inc. 12,845,822 43,742 West Pharmaceutical Services, Inc. 5,414,822 ------------- Total Health Care Equipment & Supplies $ 26,982,597 ----------------------------------------------------------------------------------------------- Health Care Providers & Services -- 3.4% 85,673(a) Laboratory Corp. of America Holdings $ 13,700,826 97,349 Universal Health Services, Inc., Class B 12,350,668 ------------- Total Health Care Providers & Services $ 26,051,494 ----------------------------------------------------------------------------------------------- Hotels, Restaurants & Leisure -- 2.8% 101,984 Dunkin' Brands Group, Inc. $ 7,611,066 254,570(a) Norwegian Cruise Line Holdings, Ltd. 14,355,202 ------------- Total Hotels, Restaurants & Leisure $ 21,966,268 ----------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 19 Schedule of Investments | 4/30/19 (unaudited) (continued) ------------------------------------------------------------------------------------------------ Shares Value ------------------------------------------------------------------------------------------------ Household Durables -- 3.9% 57,841(a) Mohawk Industries, Inc. $ 7,880,836 458,777 PulteGroup, Inc. 14,433,125 57,896 Whirlpool Corp. 8,037,123 ------------- Total Household Durables $ 30,351,084 ----------------------------------------------------------------------------------------------- Insurance -- 7.5% 77,399 American Financial Group, Inc. $ 8,013,118 208,820 Assured Guaranty, Ltd. 9,960,714 253,869 Brown & Brown, Inc. 8,060,341 142,379 First American Financial Corp. 8,124,146 218,800 Lincoln National Corp. 14,598,336 401,756 Old Republic International Corp. 8,983,264 ------------- Total Insurance $ 57,739,919 ----------------------------------------------------------------------------------------------- IT Services -- 4.5% 202,510 Booz Allen Hamilton Holding Corp. $ 12,006,818 209,203 DXC Technology Co. 13,753,005 62,638(a) Euronet Worldwide, Inc. 9,388,810 ------------- Total IT Services $ 35,148,633 ----------------------------------------------------------------------------------------------- Life Sciences Tools & Services -- 1.0% 98,322 Agilent Technologies, Inc. $ 7,718,277 ------------- Total Life Sciences Tools & Services $ 7,718,277 ----------------------------------------------------------------------------------------------- Machinery -- 7.6% 112,847(a) Gardner Denver Holdings, Inc. $ 3,808,586 187,793 Ingersoll-Rand Plc 23,025,300 189,372 PACCAR, Inc. 13,572,291 77,058 Stanley Black & Decker, Inc. 11,296,703 146,669 Timken Co. 7,032,778 ------------- Total Machinery $ 58,735,658 ----------------------------------------------------------------------------------------------- Metals & Mining -- 0.6% 375,106 Freeport-McMoRan, Inc. $ 4,617,555 ------------- Total Metals & Mining $ 4,617,555 ----------------------------------------------------------------------------------------------- Multiline Retail -- 2.3% 141,701 Dollar General Corp. $ 17,867,079 ------------- Total Multiline Retail $ 17,867,079 ----------------------------------------------------------------------------------------------- Multi-Utilities -- 2.5% 328,014 Public Service Enterprise Group, Inc. $ 19,566,035 ------------- Total Multi-Utilities $ 19,566,035 ----------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 20 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 ------------------------------------------------------------------------------------------------ Shares Value ------------------------------------------------------------------------------------------------ Oil, Gas & Consumable Fuels -- 5.7% 100,691 Diamondback Energy, Inc. $ 10,712,515 638,552 Marathon Oil Corp. 10,880,926 391,218 Murphy Oil Corp. 10,656,778 124,406 PBF Energy, Inc. 4,177,553 44,886 Pioneer Natural Resources Co. 7,471,724 ------------- Total Oil, Gas & Consumable Fuels $ 43,899,496 ----------------------------------------------------------------------------------------------- Pharmaceuticals -- 0.8% 45,208(a) Jazz Pharmaceuticals Plc $ 5,866,642 ------------- Total Pharmaceuticals $ 5,866,642 ----------------------------------------------------------------------------------------------- Road & Rail -- 1.0% 64,769 Kansas City Southern $ 7,975,655 ------------- Total Road & Rail $ 7,975,655 ----------------------------------------------------------------------------------------------- Semiconductors & Semiconductor Equipment -- 2.4% 51,976 Lam Research Corp. $ 10,781,382 353,864(a) ON Semiconductor Corp. 8,160,104 ------------- Total Semiconductors & Semiconductor Equipment $ 18,941,486 ----------------------------------------------------------------------------------------------- Specialty Retail -- 4.6% 217,050 Aaron's, Inc. $ 12,087,515 155,418 Dick's Sporting Goods, Inc. 5,750,466 16,575(a) O'Reilly Automotive, Inc. 6,274,798 111,112 Tractor Supply Co. 11,500,092 ------------- Total Specialty Retail $ 35,612,871 ----------------------------------------------------------------------------------------------- Technology Hardware, Storage & Peripherals -- 1.0% 106,998 NetApp, Inc. $ 7,794,804 ------------- Total Technology Hardware, Storage & Peripherals $ 7,794,804 ----------------------------------------------------------------------------------------------- Textiles, Apparel & Luxury Goods -- 0.5% 33,391 PVH Corp. $ 4,307,105 ------------- Total Textiles, Apparel & Luxury Goods $ 4,307,105 ----------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- 1.2% 398,430 Radian Group, Inc. $ 9,331,231 ------------- Total Thrifts & Mortgage Finance $ 9,331,231 ----------------------------------------------------------------------------------------------- TOTAL COMMON STOCKS (Cost $655,638,844) $ 759,668,148 ----------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 21 Schedule of Investments | 4/30/19 (unaudited) (continued) ------------------------------------------------------------------------------------------------ Principal Amount USD ($) Value ------------------------------------------------------------------------------------------------ U.S. GOVERNMENT AND AGENCY OBLIGATIONS -- 2.8% of Net Assets 11,845,000(b) U.S. Treasury Bills, 5/7/19 $ 11,840,320 9,550,000(b) U.S. Treasury Bills, 5/14/19 9,541,778 ------------------------------------------------------------------------------------------------ TOTAL U.S. GOVERNMENT AND AGENCY OBLIGATIONS (Cost $21,382,181) $ 21,382,098 ------------------------------------------------------------------------------------------------ TOTAL INVESTMENTS IN UNAFFILIATED ISSUERS -- 100.8% (Cost $677,021,025) $ 781,050,246 ------------------------------------------------------------------------------------------------ OTHER ASSETS AND LIABILITIES -- (0.8)% $ (6,021,963) ------------------------------------------------------------------------------------------------ NET ASSETS -- 100.0% $ 775,028,283 ================================================================================================ 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 April 30, 2019, aggregated $355,968,305 and $427,894,064, respectively. The Fund is permitted to engage in purchase and sale transactions ("cross trades") with certain funds and accounts for which the 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 April 30, 2019, the Fund did not engage in cross trade activity. At April 30, 2019, the net unrealized appreciation on investments based on cost for federal tax purposes of $679,931,328 was as follows: Aggregate gross unrealized appreciation for all investments in which there is an excess of value over tax cost $ 114,902,910 Aggregate gross unrealized depreciation for all investments in which there is an excess of tax cost over value (13,783,992) ------------- Net unrealized appreciation $ 101,118,918 ============= 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 accompanying notes are an integral part of these financial statements. 22 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 The following is a summary of the inputs used as of April 30, 2019, in valuing the Fund's investments: --------------------------------------------------------------------------------------------- Level 1 Level 2 Level 3 Total --------------------------------------------------------------------------------------------- Common Stocks $759,668,148 $ -- $ -- $759,668,148 U.S. Government and Agency Obligations -- 21,382,098 -- 21,382,098 --------------------------------------------------------------------------------------------- Total Investments in Securities $759,668,148 $21,382,098 $ -- $781,050,246 ============================================================================================= During the six months ended April 30, 2019, there were no transfers between Levels 1, 2 and 3. The accompanying notes are an integral part of these financial statements. Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 23 Statement of Assets and Liabilities | 4/30/19 (unaudited) ASSETS: Investments in unaffiliated issuers, at value (cost $677,021,025) $781,050,246 Cash 1,066,562 Receivables -- Investment securities sold 1,073,018 Fund shares sold 152,626 Dividends 200,769 Other assets 55,180 -------------------------------------------------------------------------------------------- Total assets $783,598,401 ============================================================================================ LIABILITIES: Payables -- Investment securities purchased $ 7,880,785 Fund shares repurchased 365,805 Distributions 1,059 Trustees' fees 3,310 Due to affiliates 106,837 Accrued expenses 212,322 -------------------------------------------------------------------------------------------- Total liabilities $ 8,570,118 ============================================================================================ NET ASSETS: Paid-in capital $684,098,939 Distributable earnings 90,929,344 -------------------------------------------------------------------------------------------- Net assets $775,028,283 ============================================================================================ NET ASSET VALUE PER SHARE: No par value (unlimited number of shares authorized) Class A (based on $718,114,204/32,827,200 shares) $ 21.88 Class C (based on $16,195,071/1,118,120 shares) $ 14.48 Class K (based on $1,643,528/75,085 shares) $ 21.89 Class R (based on $10,355,372/484,921 shares) $ 21.35 Class Y (based on $28,720,108/1,209,691 shares) $ 23.74 MAXIMUM OFFERING PRICE PER SHARE: Class A (based on $21.88 net asset value per share/100%-5.75% maximum sales charge) $ 23.21 ============================================================================================ The accompanying notes are an integral part of these financial statements. 24 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 Statement of Operations (unaudited) For the Six Months Ended 4/30/19 INVESTMENT INCOME: Dividends from unaffiliated issuers $7,855,318 Interest from unaffiliated issuers 102,860 ------------------------------------------------------------------------------------------------------ Total investment income $ 7,958,178 ====================================================================================================== EXPENSES: Management fees Basic fee $2,522,355 Performance Adjustment (440,530) Administrative expense 182,288 Transfer agent fees Class A 314,596 Class C 17,428 Class K 54 Class R 11,248 Class Y 16,423 Distribution fees Class A 853,387 Class C 83,133 Class R 24,817 Shareowner communications expense 140,701 Custodian fees 10,259 Registration fees 34,662 Professional fees 27,538 Printing expense 34,895 Trustees' fees 15,535 Insurance expense 2,422 Miscellaneous 57,052 ------------------------------------------------------------------------------------------------------ Total expenses $ 3,908,263 ------------------------------------------------------------------------------------------------------ Net investment income $ 4,049,915 ------------------------------------------------------------------------------------------------------ REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS: Net realized gain (loss) on: Investments in unaffiliated issuers $(11,177,220) ------------------------------------------------------------------------------------------------------ Change in net unrealized appreciation (depreciation) on: Investments in unaffiliated issuers $ 64,017,141 ------------------------------------------------------------------------------------------------------ Net realized and unrealized gain (loss) on investments $ 52,839,921 ------------------------------------------------------------------------------------------------------ Net increase in net assets resulting from operations $ 56,889,836 ====================================================================================================== The accompanying notes are an integral part of these financial statements. Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 25 Statements of Changes in Net Assets ------------------------------------------------------------------------------------------------------ Six Months Ended Year 4/30/19 Ended (unaudited) 10/31/18 ------------------------------------------------------------------------------------------------------ FROM OPERATIONS: Net investment income (loss) $ 4,049,915 $ 5,401,523 Net realized gain (loss) on investments (11,177,220) 71,382,669 Change in net unrealized appreciation (depreciation) on investments 64,017,141 (132,465,402) ------------------------------------------------------------------------------------------------------ Net increase (decrease) in net assets resulting from operations $ 56,889,836 $ (55,681,210) ------------------------------------------------------------------------------------------------------ DISTRIBUTIONS TO SHAREOWNERS: Class A ($2.27 and $2.11 per share, respectively) $(71,479,958) $ (66,998,046) Class C ($2.09 and $2.02 per share, respectively) (2,421,399) (5,168,871) Class K ($2.34 and $2.20 per share, respectively) (174,867) (2,233,949) Class R ($2.16 and $2.02 per share, respectively) (1,014,076) (1,109,167) Class Y ($2.32 and $2.16 per share, respectively) (2,603,260) (2,918,223) ------------------------------------------------------------------------------------------------------ Total distributions to shareowners $(77,693,560) $ (78,428,256) ------------------------------------------------------------------------------------------------------ FROM FUND SHARE TRANSACTIONS: Net proceeds from sales of shares $ 23,070,743 $ 60,974,927 Reinvestment of distributions 74,559,254 73,099,899 Cost of shares repurchased (70,108,017) (200,505,997) ------------------------------------------------------------------------------------------------------ Net increase (decrease) in net assets resulting from Fund share transactions $ 27,521,980 $ (66,431,171) ------------------------------------------------------------------------------------------------------ Net increase (decrease) in net assets $ 6,718,256 $(200,540,637) NET ASSETS: Beginning of period $768,310,027 $ 968,850,664 ------------------------------------------------------------------------------------------------------ End of period $775,028,283 $ 768,310,027 ====================================================================================================== The accompanying notes are an integral part of these financial statements. 26 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 -------------------------------------------------------------------------------------------------------- Six Months Six Months Ended Ended 4/30/19 4/30/19 Year Ended Year Ended Shares Amount 10/31/18 10/31/18 (unaudited) (unaudited) Shares Amount -------------------------------------------------------------------------------------------------------- Class A Shares sold 621,130 $ 13,435,772 1,684,495 $ 41,686,775 Reinvestment of distributions 3,335,025 68,671,357 2,588,720 64,283,020 Less shares repurchased (2,701,575) (55,490,879) (4,656,638) (115,614,113) -------------------------------------------------------------------------------------------------------- Net increase (decrease) 1,254,580 $ 26,616,250 (383,423) $ (9,644,318) ======================================================================================================== Class C Shares sold 132,595 $ 1,779,162 236,324 $ 4,059,736 Reinvestment of distributions 167,435 2,297,207 288,609 4,958,299 Less shares repurchased (373,138) (5,069,896) (1,928,864) (33,241,582) -------------------------------------------------------------------------------------------------------- Net decrease (73,108) $ (993,527) (1,403,931) $ (24,223,547) ======================================================================================================== Class K Shares sold 4,754 $ 100,110 196,793 $ 4,985,892 Reinvestment of distributions 8,512 174,867 5,210 129,819 Less shares repurchased (13,195) (282,986) (1,128,285) (27,878,904) -------------------------------------------------------------------------------------------------------- Net increase (decrease) 71 $ (8,009) (926,282) $ (22,763,193) ======================================================================================================== Class R Shares sold 54,674 $ 1,102,230 65,576 $ 1,571,662 Reinvestment of distributions 48,761 982,986 44,593 1,079,604 Less shares repurchased (85,406) (1,697,389) (210,664) (5,171,255) -------------------------------------------------------------------------------------------------------- Net increase (decrease) 18,029 $ 387,827 (100,495) $ (2,519,989) ======================================================================================================== Class Y Shares sold 318,460 $ 6,653,469 325,163 $ 8,670,862 Reinvestment of distributions 109,119 2,432,837 98,942 2,649,157 Less shares repurchased (347,635) (7,566,867) (694,425) (18,600,143) -------------------------------------------------------------------------------------------------------- Net increase (decrease) 79,944 $ 1,519,439 (270,320) $ (7,280,124) ======================================================================================================== The accompanying notes are an integral part of these financial statements. Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 27 Financial Highlights ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year Year Year 4/30/19 Ended Ended Ended Ended Ended (unaudited) 10/31/18 10/31/17 10/31/16* 10/31/15* 10/31/14* ------------------------------------------------------------------------------------------------------------------------------------ Class A Net asset value, beginning of period $ 22.50 $ 26.27 $ 23.66 $ 25.30 $ 28.37 $ 27.42 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.11(a) $ 0.16(a) $ 0.11(a) $ 0.12(a) $ 0.14(a) $ 0.15 Net realized and unrealized gain (loss) on investments 1.54 (1.82) 4.10 0.58 (0.01) 3.71 ----------------------------------------------------------------------------------------------------------------------------------- Net increase (decrease) from investment operations $ 1.65 $ (1.66) $ 4.21 $ 0.70 $ 0.13 $ 3.86 ----------------------------------------------------------------------------------------------------------------------------------- Distributions to shareowners: Net investment income $ (0.18) $ (0.09) $ (0.11) $ (0.08) $ (0.11) $ (0.11) Net realized gain (2.09) (2.02) (1.49) (2.26) (3.09) (2.80) ----------------------------------------------------------------------------------------------------------------------------------- Total distributions $ (2.27) $ (2.11) $ (1.60) $ (2.34) $ (3.20) $ (2.91) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ (0.62) $ (3.77) $ 2.61 $ (1.64) $ (3.07) $ 0.95 ----------------------------------------------------------------------------------------------------------------------------------- Net asset value, end of period $ 21.88 $ 22.50 $ 26.27 $ 23.66 $ 25.30 $ 28.37 ==================================================================================================================================== Total return (b) 8.04%(c) (7.05)% 18.56% 2.94% 0.22% 15.47% Ratio of net expenses to average net assets 1.04%(d) 1.02% 1.04% 1.08% 1.05% 1.04% Ratio of net investment income (loss) to average net assets 1.11%(d) 0.63% 0.43% 0.53% 0.54% 0.58% Portfolio turnover rate 48%(c) 78% 58% 70% 90% 61% Net assets, end of period (in thousands) $718,114 $710,468 $839,636 $791,576 $856,629 $956,082 ==================================================================================================================================== * 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) Annualized. The accompanying notes are an integral part of these financial statements. 28 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year Year Year 4/30/19 Ended Ended Ended Ended Ended (unaudited) 10/31/18 10/31/17 10/31/16* 10/31/15* 10/31/14* ------------------------------------------------------------------------------------------------------------------------------------ Class C Net asset value, beginning of period $ 15.53 $ 18.82 $ 17.42 $ 19.29 $ 22.42 $ 22.33 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.02(a) $ (0.03)(a) $ (0.07)(a) $ (0.05)(a)(b) $ (0.06)(a) $ (0.05) Net realized and unrealized gain (loss) on investments 1.02 (1.24) 2.96 0.44 0.02 2.94 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ 1.04 $ (1.27) $ 2.89 $ 0.39 $ (0.04) $ 2.89 ------------------------------------------------------------------------------------------------------------------------------------ Distributions to shareowners: Net investment income $ -- $ -- $ -- $ -- $ -- $ -- Net realized gain (2.09) (2.02) (1.49) (2.26) (3.09) (2.80) ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $ (2.09) $ (2.02) $ (1.49) $ (2.26) $ (3.09) $ (2.80) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ (1.05) $ (3.29) $ 1.40 $ (1.87) $ (3.13) $ 0.09 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 14.48 $ 15.53 $ 18.82 $ 17.42 $ 19.29 $ 22.42 ==================================================================================================================================== Total return (c) 7.46%(d) (7.77)%(e) 17.55% 2.13% (0.59)% 14.50% Ratio of net expenses to average net assets 1.96%(f) 1.83% 1.87% 1.92% 1.90% 1.86% Ratio of net investment income (loss) to average net assets 0.22%(f) (0.15)% (0.40)% (0.30)% (0.31)% (0.24)% Portfolio turnover rate 48%(d) 78% 58% 70% 90% 61% Net assets, end of period (in thousands) $16,195 $18,495 $48,840 $51,641 $60,473 $69,090 ==================================================================================================================================== * 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 net investment income on the Statement of Operations due to timing of the sales and repurchase of shares. (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 October 31, 2018, the total return would have been (7.82)%. (f) Annualized. The accompanying notes are an integral part of these financial statements. Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 29 Financial Highlights (continued) ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year 4/30/19 Ended Ended Ended 3/2/15 to (unaudited) 10/31/18 10/31/17 10/31/16* 10/31/15* ------------------------------------------------------------------------------------------------------------------------------------ Class K Net asset value, beginning of period $22.56 $26.34 $ 23.72 $ 25.37 $ 26.76 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.15(a) $ 0.21(a) $ 0.19(a) $ 0.21(a) $ 0.15(a) Net realized and unrealized gain (loss) on investments 1.52 (1.79) 4.11 0.58 (1.54) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ 1.67 $(1.58) $ 4.30 $ 0.79 $ (1.39) ------------------------------------------------------------------------------------------------------------------------------------ Distributions to shareowners: Net investment income $(0.25) $(0.18) $ (0.19) $ (0.18) $ -- Net realized gain (2.09) (2.02) (1.49) (2.26) -- ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $(2.34) $(2.20) $ (1.68) $ (2.44) $ -- ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $(0.67) $(3.78) $ 2.62 $ (1.65) $ (1.39) ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $21.89 $22.56 $ 26.34 $ 23.72 $ 25.37 ==================================================================================================================================== Total return (b) 8.23%(c) (6.75)%(d) 18.98% 3.36% (5.19)%(c) Ratio of net expenses to average net assets 0.67%(e) 0.68% 0.68% 0.71% 0.65%(e) Ratio of net investment income (loss) to average net assets 1.49%(e) 0.83% 0.74% 0.91% 0.85%(e) Portfolio turnover rate 48%(c) 78% 58% 70% 0.90% Net assets, end of period (in thousands) $1,644 $1,693 $26,373 $12,693 $16,103 ==================================================================================================================================== * 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 year ended October 31, 2018, the total return would have been (6.80)%. (e) Annualized. The accompanying notes are an integral part of these financial statements. 30 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year Year Year 4/30/19 Ended Ended Ended Ended Ended (unaudited) 10/31/18 10/31/17 10/31/16* 10/31/15* 10/31/14* ------------------------------------------------------------------------------------------------------------------------------------ Class R Net asset value, beginning of period $ 21.94 $ 25.70 $ 23.18 $ 24.84 $ 27.91 $ 27.02 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.07(a) $ 0.04(a) $ 0.00(a)(b) $ 0.03(a) $ 0.04(a) $ 0.07 Net realized and unrealized gain (loss) on investments 1.50 (1.78) 4.02 0.57 0.00(b) 3.63 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ 1.57 $ (1.74) $ 4.02 $ 0.60 $ 0.04 $ 3.70 ------------------------------------------------------------------------------------------------------------------------------------ Distributions to shareowners: Net investment income $ (0.07) $ -- $ (0.01) $ -- $ (0.02) $ (0.01) Net realized gain (2.09) (2.02) (1.49) (2.26) (3.09) (2.80) ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $ (2.16) $ (2.02) $ (1.50) $ (2.26) $ (3.11) $ (2.81) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ (0.59) $ (3.76) $ 2.52 $ (1.66) $ (3.07) $ 0.89 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 21.35 $ 21.94 $ 25.70 $ 23.18 $ 24.84 $ 27.91 ==================================================================================================================================== Total return (c) 7.78%(d) (7.50)% 18.11% 2.54% (0.16)% 15.03% Ratio of net expenses to average net assets 1.42%(e) 1.48% 1.46% 1.47% 1.44% 1.43% Ratio of net investment income (loss) to average net assets 0.73%(e) 0.18% 0.02% 0.15% 0.16% 0.20% Portfolio turnover rate 48%(d) 78% 58% 70% 90% 61% Net assets, end of period (in thousands) $10,355 $10,244 $14,579 $15,462 $21,023 $26,909 ==================================================================================================================================== * 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) Amount rounds to less than $0.01 per share. (c) 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. (d) Not annualized. (e) Annualized. The accompanying notes are an integral part of these financial statements. Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 31 Financial Highlights (continued) ------------------------------------------------------------------------------------------------------------------------------------ Six Months Ended Year Year Year Year Year 4/30/19 Ended Ended Ended Ended Ended (unaudited) 10/31/18 10/31/17 10/31/16* 10/31/15* 10/31/14* ------------------------------------------------------------------------------------------------------------------------------------ Class Y Net asset value, beginning of period $ 24.26 $ 28.16 $ 25.25 $ 26.84 $ 29.91 $ 28.74 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.15(a) $ 0.23(a) $ 0.18(a) $ 0.19(a) $ 0.25(a) $ 0.29 Net realized and unrealized gain (loss) on investments 1.65 (1.97) 4.38 0.63 (0.02) 3.87 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ 1.80 $ (1.74) $ 4.56 $ 0.82 $ 0.23 $ 4.16 ------------------------------------------------------------------------------------------------------------------------------------ Distributions to shareowners: Net investment income $ (0.23) $ (0.14) $ (0.16) $ (0.15) $ (0.21) $ (0.19) Net realized gain (2.09) (2.02) (1.49) (2.26) (3.09) (2.80) ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $ (2.32) $ (2.16) $ (1.65) $ (2.41) $ (3.30) $ (2.99) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ (0.52) $ (3.90) $ 2.91 $ (1.59) $ (3.07) $ 1.17 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 23.74 $ 24.26 $ 28.16 $ 25.25 $ 26.84 $ 29.91 ==================================================================================================================================== Total return (b) 8.14%(c) (6.85)% 18.85% 3.23% 0.53% 15.89% Ratio of net expenses to average net assets 0.79%(d) 0.78% 0.81% 0.82% 0.73% 0.67% Ratio of net investment income (loss) to average net assets 1.34%(d) 0.88% 0.66% 0.79% 0.90% 0.95% Portfolio turnover rate 48%(c) 78% 58% 70% 90% 61% Net assets, end of period (in thousands) $28,720 $27,410 $39,423 $33,339 $31,294 $83,545 ==================================================================================================================================== * 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) Annualized. The accompanying notes are an integral part of these financial statements. 32 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 Notes to Financial Statements | 4/30/19 (unaudited) 1. Organization and Significant Accounting Policies Pioneer Mid Cap Value Fund (the "Fund") is 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 capital appreciation by investing in a diversified portfolio of securities consisting primarily of common stocks. The Fund offers five classes of shares designated as Class A, Class C, Class K, Class R and Class Y shares. 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 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. 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 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 33 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. 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 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. 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 34 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 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 April 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. 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. 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 April 30, 2019, the Fund did not accrue any interest or penalties with respect to uncertain tax positions, which, if applicable, would be recorded as Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 35 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. 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 October 31, 2018 was as follows: -------------------------------------------------------------------------- 2018 -------------------------------------------------------------------------- Distributions paid from: Ordinary income $ 3,375,935 Long-term capital gain 75,052,321 -------------------------------------------------------------------------- Total $78,428,356 ========================================================================== The following shows the components of distributable earnings (losses) on a federal income tax basis at October 31, 2018: -------------------------------------------------------------------------- 2018 -------------------------------------------------------------------------- Undistributed ordinary income $ 3,206,080 Undistributed long-term capital gain 71,425,210 Net unrealized appreciation 37,101,778 -------------------------------------------------------------------------- Total $111,733,068 ========================================================================== The difference between book basis and tax basis unrealized appreciation is attributable to the tax deferral of losses on wash sales. D. Fund Shares The Fund records sales and repurchases of its shares as of trade date. The Distributor earned $14,937 in underwriting commissions on the sale of Class A shares during the six months ended April 30, 2019. E. 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. 36 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 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). 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. F. 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 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 37 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 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. 2. Management Agreement The Adviser manages the Fund's portfolio. Management fees are calculated daily at the annual rate of 0.70% of the Fund's average daily net assets up to $500 million, 0.65% on the next $500 million, 0.625% on the next $3 billion and 0.60% on the excess over $4 billion. The basic fee (fee before performance adjustment) can increase or decrease by a maximum of 0.10% based on the investment performance of the Fund's Class A shares as compared to the Russell Midcap Value Index. The performance comparison is made for a rolling 36-month period. In addition, the Adviser contractually limits any positive adjustment of the Fund's management fee to 0.10% of the Fund's average daily net assets on an annual basis (i.e., to a maximum management fee of 0.80% of average daily net assets after the performance adjustment). For the six months ended, the aggregate performance adjustment resulted in a decrease of $440,530 to the basic fee. For the six months ended April 30, 2019 the net management fee was equivalent to 0.56% (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. Included in "Due to affiliates" reflected on the Statement of Assets and Liabilities is $67,563 in management fees, administrative costs and certain other reimbursements payable to the Adviser at April 30, 2019. 38 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 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 April 30, 2019, such out-of-pocket expenses by class of shares were as follows: -------------------------------------------------------------------------------- Shareowner Communications: -------------------------------------------------------------------------------- Class A $130,323 Class C 7,174 Class K 37 Class R 1,691 Class Y 1,476 -------------------------------------------------------------------------------- Total $140,701 ================================================================================ 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. Pursuant to the Plan, the Fund further pays the Distributor 0.50% of the average daily net assets attributable to Class R shares for distribution services. Included in "Due to affiliates" reflected on the Statement of Assets and Liabilities is $39,274 in distribution fees payable to the Distributor at April 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 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. Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 39 In addition, redemptions of Class A and Class C shares (except Class K, Class R and Class Y 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 is no CDSC for Class K, Class R or Class Y shares. Proceeds from the CDSCs are paid to the Distributor. For the six months ended April 30, 2019, CDSCs in the amount of $1,635 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 that is in the amount of $250 million. Prior to August 1, 2018, the credit facility was in the amount of $195 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 Fund pays 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 April 30, 2019, the Fund had no borrowings under the credit facility. 40 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 Trustees, Officers and Service Providers Trustees Officers Thomas J. Perna, Chairman Lisa M. Jones, President and David R. Bock Chief Executive Officer Benjamin M. Friedman Mark E. Bradley, Treasurer and Margaret B.W. Graham Chief Financial and Lisa M. Jones Accounting Officer Lorraine H. Monchak Christopher J. Kelley, Secretary and Marguerite A. Piret Chief Legal Officer 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. Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 41 This page is for your notes. 42 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 This page is for your notes. Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 43 This page is for your notes. 44 Pioneer Mid Cap Value Fund | Semiannual Report | 4/30/19 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 19385-13-0619 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. 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 Mid Cap Value Fund By (Signature and Title)* /s/ Lisa M. Jones Lisa M. Jones, President & Chief Executive Officer Date July 1, 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 July 1, 2019 By (Signature and Title)* /s/ Mark E. Bradley Mark E. Bradley, Treasurer & Chief Accounting & Financial Officer Date July 1, 2019 * Print the name and title of each signing officer under his or her signature.