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, 2017 through October 31, 2018 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 -------------------------------------------------------------------------------- Annual Report | October 31, 2018 -------------------------------------------------------------------------------- Ticker Symbols: Class A PCGRX Class C PCCGX Class K PMCKX Class R PCMRX Class Y PYCGX [LOGO] Amundi Pioneer ============== ASSET MANAGEMENT visit us: www.amundipioneer.com 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 Report of Independent Registered Public Accounting Firm 41 Additional Information 43 Approval of Investment Management Agreement 45 Trustees, Officers and Service Providers 50 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 1 President's Letter Despite economic news that has remained generally positive throughout 2018, market volatility has increased significantly this year compared with 2017. October was a particularly poor month for both U.S. and global equity markets, as every major stock market index finished the month in negative territory. Results have been more mixed on the fixed-income side, with rising interest rates pushing down most year-to-date returns. On the economic front, U.S. gross domestic product (GDP) growth exceeded 4% in the second quarter of 2018 and topped 3% once again in the third quarter. The low unemployment rate has continued, with initial jobless claims recently hitting a multi-decade low and consumer and small-business confidence also achieving levels not seen in many years. Despite the good economic news, and even though wages have been rising, inflation expectations have not risen significantly. For its part, the U.S. Federal Reserve System (the Fed) has continued with its tightening of monetary policy by raising interest rates three times in 2018, while moving forward with the tapering of its balance sheet, a process which began in October 2017. The greater market volatility this year as compared to last year has been driven by several factors. The aforementioned rising interest rates have been one reason, while the uncertainty surrounding U.S. trade policy has, at times, also led to unsettled markets. Of course, in today's global economy, risk factors extend well beyond U.S. borders, and in recent months investors have grappled with various issues on the international front, including questions surrounding the United Kingdom's Brexit negotiations, concerns about the budgetary policies of the populist Italian government, and the potential impact of Turkey's economic challenges on European banks. Moreover, while trade tensions between the U.S. and Europe have moderated, questions about the future of the U.S./China trade relationship remain unresolved, and any major fracture in that relationship could have a negative impact on China's economy and, by extension, on its Asian trade partners. With regard to our market outlook, over the medium term, we believe the fundamental investment case for U.S. equities remains in place, with support from the fairly positive economic backdrop and with an additional lift potentially coming from the investment side as U.S. businesses consider increasing capital expenditures. We do believe market volatility will persist and, therefore, careful selection of investment themes, sector allocations, and individual stocks will be increasingly relevant to overall performance, as the 2 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 maturity of the economic and market cycles could eventually become headwinds. We believe a focus on owning shares of quality companies trading at reasonable prices is key to navigating the current equity-market phase. In fixed income, we have taken a more cautious approach across our core portfolios with regard to credit-sensitive debt such as corporate bonds, favoring quality and liquidity. As interest rates have risen, we find that short-and intermediate-term U.S. Treasuries have become more attractive, and that agency mortgage-backed securities (MBS) and high-quality, non-agency MBS now also offer lower downside risk. In general, we think structured sectors (such as asset-backed securities and MBS) are more attractive than corporate sectors. We believe this year's market fluctuations as well as increased risk factors within the global economy have served to remind investors of the importance of active management. Since 1928, active management has been the foundation of Amundi Pioneer's investment approach. We believe active management is especially important during periods of volatility, and that our shareowners can benefit from the experience and tenure of our investment teams, who work collaboratively to make active and informed decisions across our funds. As always, and particularly during times of market uncertainty, 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. 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. October 31, 2018 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 | Annual Report | 10/31/18 3 Portfolio Management Discussion | 10/31/18 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 12-month period ended October 31, 2018. 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 12-month period ended October 31, 2018? A Pioneer Mid Cap Value Fund's Class A shares returned -7.05% at net asset value during the 12-month period ended October 31, 2018, while the Fund's benchmark, the Russell Midcap Value Index, returned 0.16%. During the same period, the average return of the 412 mutual funds in Morningstar's Mid-Cap Value Funds category was -0.20%. Q How would you describe the investment environment for mid-cap equities during the six-month period ended April 30, 2018? A Mid-cap equity indices showed gains during the first six months of the period, but the advances were moderate, as the Fund's benchmark, the Russell Midcap Value Index (the Russell Index), returned 2.55% from November 1, 2017, through April 30, 2018. Mid-cap stocks turned negative over the second half of the period, however, as the Russell Index returned -2.32% over the six-month period between May 1, 2018, and October 31, 2018, and mid-cap equities ended the full 12 months with an essentially flat return of 0.16%. Despite multiple strong rallies over the 12-month period, the market overall began exhibiting many defensive characteristics as the period progressed, as the Federal Reserve (the Fed) continued to raise interest rates and concerns over U.S. trade policy as well as other geopolitical issues led to increased volatility, even while unemployment remained extremely low and U.S. gross domestic product (GDP) exceeded 4% in the second quarter and 3% in the third quarter. The good economic news notwithstanding, the market clearly began to perceive that things were beginning to slow down and that a recession could be on the horizon. The real estate and utilities sectors benefited from the market's move toward more defensive stocks as the period progressed, * Mr. Stanish became a portfolio manager on the Fund effective September 28, 2018. ** Mr. Haddad became a portfolio manager on the Fund effective March 1, 2018. 4 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 even though Fed interest-rate hikes have typically caused those sectors to underperform in the past. The market also had a desire for stocks of companies with sustainable growth prospects independent of the economic cycle, which led to mid-cap growth stocks significantly outperforming mid-cap value stocks over the final six months of the period, and over the full 12 months. Q Which of your investment strategies either contributed to or detracted from the Fund's performance relative to the Russell Index during the 12-month period ended October 31, 2018? A Stock selection was the primary factor in the Fund's underperformance of the Russell Index during the period, with results in consumer discretionary, energy, financials, and information technology detracting the most from benchmark-relative returns. We correctly predicted the macroeconomic environment heading into the period, as we foresaw steady economic growth and rising interest rates, but the sector bets we made in the portfolio to align with those views did not work out given that the market moved in the opposite direction of those macroeconomic views as the period progressed. We had positioned the Fund for an "offensive" market environment and ended up witnessing a "defensive" one, despite periods of significant rallies over the 12 months. In a rising-rate environment, we expected financials to do well and for real estate and utilities, which usually underperform in such conditions, to do poorly. The reverse was true, however, as real estate and utilities benefited from the market's move toward more defensive stocks over the second half of the period. As we mentioned earlier, the market also had a desire for companies with sustainable growth prospects independent of the economic cycle, whereas many of the Fund's holdings are cyclical in nature. We do not foresee a recession on the horizon, but it's clear that some factors, including rising rates, trade concerns, and other global tensions have had an effect on the market. We believed the economic cycle would last longer, but the market clearly seems to think that the end of the cycle is almost at hand. The Fund's management team recognizes the recent performance issues and we have been making some changes to our approach, including striving for more balance between higher-quality value and lower-quality value stocks in the portfolio. Historically, the Fund has had a lower-quality, low price-to-earnings (P/E) bent. Pioneer Mid Cap Value Fund will always be a mid-cap value portfolio, but we will attempt to achieve more balance going forward. We also made some personnel changes to the team and refined our stock screening process, while increasing the number of holdings in the portfolio -- though the Fund remains fairly concentrated. Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 5 At the individual security level, the portfolio holdings that hurt benchmark-relative performance the most over the 12-month period were Goodyear Tire & Rubber, Owens Corning, Unum Group, Acacia Communications, and Norwegian Cruise Line. Shares of Goodyear Tire & Rubber declined during the period as the company missed on an earnings estimate. Increased costs for raw materials as well as other expenses were drags on Goodyear's earnings, while a competitive business environment and difficult industry conditions led to reduced sales and decreased profitability. We sold the stock from the portfolio during the period. We also sold building-products company Owens Corning after the stock underperformed due to several operational missteps by management, combined with the higher cost of materials. In addition, we saw better opportunities in that area of the market and decided to move on. Insurer Unum Group was another key detractor from the Fund's benchmark-relative returns. Insurance companies have usually done well during higher interest-rate environments, but Unum's business recently experienced a $600 million charge (write-off) from its legacy long-term care policies, which it no longer sells. The situation is not unique to Unum, and the company feels that it is in pretty good shape going forward. The market, however, appears to need some convincing on that point. We continue to hold the stock in the portfolio as we like the valuation. Another performance detractor was the portfolio's holding in Acacia Communications, a maker of optical products. The company struggled earlier in the period after the U.S. government advanced a new rule that would limit the ability of Chinese telecommunications companies to sell their products in this country. ZTE, the large Chinese telecom firm, is one of Acacia's biggest customers, and the government's action caused a large drop in Acacia's stock price (though it later regained some ground). We sold the position. Finally, shares of Norwegian Cruise Lines detracted from the Fund's relative performance due to market fears that the cruise industry will add too much capacity. The rising cost of oil (fuel) also did not help matters. In addition, the Chinese cruise market hasn't panned out as hoped. We still like Norwegian's stock, however, as even if capacity rises, the cruise industry has shown in the past that it can sell the extra cabins. Q Which individual portfolio holdings contributed positively to the Fund's benchmark-relative returns during the 12-month period ended October 31, 2018? A The major positive contributors to the Fund's benchmark-relative performance during the 12-month period were positions in United Continental, CDW, Microsemi, Centene, and Dollar General. Shares of airline United Continental were up during the period as the company beat third-quarter earnings estimates, while the market also reacted positively to internal improvements made by management as well as 6 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 increased capacity. Two information technology stocks, CDW and Microsemi, made significant positive contributions to the Fund's benchmark-relative performance during the 12-month period. CDW is a distributor of tech hardware and systems. We consider it a very well-run company that has continued taking market share and has now expanded into cloud services. Semiconductor firm Microsemi was acquired during the period by Microchip Technology, which drove the stock's positive performance. Centene is a managed-care health insurance firm. Industry tailwinds of an aging population and high demand are in the company's favor and helped drive its solid performance over the period. Centene is another very well-run company that has continued to take market share, and it also just completed an acquisition of Fidelis Care, which we believe will prove to be accretive. Finally, Dollar General, which is a recent addition to the Fund, fared well and contributed positively to benchmark-relative performance. Dollar General is another very well-run company that has both defensive and growth characteristics (in keeping with our revised investment approach). We believe Dollar General has the potential to successfully navigate any possible economic downturn due to the fact that it offers goods at low and affordable prices. Dollar General is also basically e-Commerce immune, since its clients rarely purchase items online. Q Did you invest the Fund in any derivative securities during the 12-month period ended October 31, 2018? A No, the Fund did not own any derivatives during the period. Q What is your outlook for mid-cap stocks as we move towards the end of the calendar year? A It's been a difficult environment for low-P/E value investors like us. The market clearly seems to be concerned about the economic cycle coming to an end. We are appreciative of that tone, but do not subscribe to it fully, as we do not foresee an imminent recession nor a bear market on the immediate horizon. Certainly, the political, trade, and interest-rate climates have contributed to choppier market conditions, and the U.S./China trade situation bears watching, as companies down the supply chain will be affected by a prolonged dispute. There is also the "tax cut hangover" effect at play, as much of the ramped-up economic activity in the wake of the tax cuts that went into effect earlier this year has begun to normalize or slow. We will be watching closely to see if the Fed moves forward with its next projected rate increase by the end of this year, or if it heeds some of the warning signs from the markets and backs off its tightening cycle, at least for a time. We are moving forward by trying to take advantage of situations where we believe the market has gotten things wrong, and may have over-discounted some stocks, while also sacrificing some valuation in order to move the portfolio's holdings up-in-quality. Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 7 With regard to sector weights, we have cut back on the Fund's financials overweight versus the Russell Index, but have increased the health care overweight. The Fund remains overweight in consumer discretionary, but is now just slightly overweight in information technology. The portfolio remains underweight in real estate and utilities, though it is less underweight as of period-end, especially in the real estate sector. The Fund is still underweight in consumer staples. 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 | Annual Report | 10/31/18 Portfolio Summary | 10/31/18 Sector Distribution -------------------------------------------------------------------------------- (As a percentage of total investments)* [THE FOLLOWING DATA WAS REPRESENTED AS A PIE CHART IN THE PRINTED MATERIAL] Financials 23.1% Industrials 15.5% Consumer Discretionary 10.7% Health Care 9.7% Real Estate 9.3% Information Technology 9.1% Energy 7.7% Materials 5.7% Utilities 4.4% Consumer Staples 2.9% Communication Services 1.9% 10 Largest Holdings -------------------------------------------------------------------------------- (As a percentage of total investments)* 1. Mosaic Co. 2.67% -------------------------------------------------------------------------------- 2. KeyCorp 2.66 -------------------------------------------------------------------------------- 3. Huntington Bancshares, Inc. 2.60 -------------------------------------------------------------------------------- 4. Ingersoll-Rand Plc 2.46 -------------------------------------------------------------------------------- 5. Marathon Oil Corp. 2.43 -------------------------------------------------------------------------------- 6. Discover Financial Services 2.40 -------------------------------------------------------------------------------- 7. Lincoln National Corp. 2.34 -------------------------------------------------------------------------------- 8. PulteGroup, Inc. 2.26 -------------------------------------------------------------------------------- 9. Radian Group, Inc. 2.24 -------------------------------------------------------------------------------- 10. Public Service Enterprise Group, Inc. 2.21 -------------------------------------------------------------------------------- * 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 security listed. Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 9 Prices and Distributions | 10/31/18 Net Asset Value per Share -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Class 10/31/18 10/31/17 -------------------------------------------------------------------------------- A $22.50 $26.27 -------------------------------------------------------------------------------- C $15.53 $18.82 -------------------------------------------------------------------------------- K $22.56 $26.34 -------------------------------------------------------------------------------- R $21.94 $25.70 -------------------------------------------------------------------------------- Y $24.26 $28.16 -------------------------------------------------------------------------------- Distributions per Share: 11/1/17-10/31/18 -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Net Investment Short-Term Long-Term Class Income Capital Gains Capital Gains -------------------------------------------------------------------------------- A $0.0875 $ -- $2.0214 -------------------------------------------------------------------------------- C $ -- $ -- $2.0214 -------------------------------------------------------------------------------- K $0.1760 $ -- $2.0214 -------------------------------------------------------------------------------- R $ -- $ -- $2.0214 -------------------------------------------------------------------------------- Y $0.1441 $ -- $2.0214 -------------------------------------------------------------------------------- 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 | Annual Report | 10/31/18 Performance Update | 10/31/18 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 October 31, 2018) ----------------------------------------------- Net Public Russell Asset Offering Midcap Value Price Value Period (NAV) (POP) Index ----------------------------------------------- 10 years 9.58% 8.94% 13.35% 5 years 5.59 4.35 8.11 1 year -7.05 -12.40 0.16 ----------------------------------------------- Expense Ratio (Per prospectus dated March 1, 2018) ----------------------------------------------- Gross ----------------------------------------------- 1.04% ----------------------------------------------- [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 10/08 $ 9,425 $10,000 10/09 $10,732 $11,452 10/10 $12,660 $14,600 10/11 $12,791 $15,452 10/12 $13,695 $17,768 10/13 $17,928 $23,711 10/14 $20,702 $27,547 10/15 $20,747 $27,675 10/16 $21,358 $29,845 10/17 $25,322 $34,953 10/18 $23,536 $35,010 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. 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 | Annual Report | 10/31/18 11 Performance Update | 10/31/18 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 October 31, 2018) ----------------------------------------------- Russell Midcap If If Value Period Held Redeemed Index ----------------------------------------------- 10 years 8.66% 8.66% 13.35% 5 years 4.74 4.74 8.11 1 year -7.77 -7.77 0.16 ----------------------------------------------- Expense Ratio (Per prospectus dated March 1, 2018) ----------------------------------------------- Gross ----------------------------------------------- 1.87% ----------------------------------------------- [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 10/08 $10,000 $10,000 10/09 $11,287 $11,452 10/10 $13,192 $14,600 10/11 $13,216 $15,452 10/12 $14,029 $17,768 10/13 $18,201 $23,711 10/14 $20,840 $27,547 10/15 $20,717 $27,675 10/16 $21,159 $29,845 10/17 $24,873 $34,953 10/18 $22,940 $35,010 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. Class 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. 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 | Annual Report | 10/31/18 Performance Update | 10/31/18 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 October 31, 2018) ----------------------------------------------- Net Russell Asset Midcap Value Value Period (NAV) Index ----------------------------------------------- 10 years 9.73% 13.35% 5 years 5.88 8.11 1 year -6.75 0.16 ----------------------------------------------- Expense Ratio (Per prospectus dated March 1, 2018) ----------------------------------------------- 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 10/08 $ 5,000,000 $ 5,000,000 10/09 $ 5,693,394 $ 5,725,994 10/10 $ 6,716,018 $ 7,300,067 10/11 $ 6,785,530 $ 7,725,976 10/12 $ 7,265,297 $ 8,883,830 10/13 $ 9,510,924 $11,855,386 10/14 $10,982,604 $13,773,289 10/15 $11,036,918 $13,837,693 10/16 $11,407,457 $14,922,273 10/17 $13,572,116 $17,476,596 10/18 $12,656,247 $17,505,231 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. 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 | Annual Report | 10/31/18 13 Performance Update | 10/31/18 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 October 31, 2018) ----------------------------------------------- Net Russell Asset Midcap Value Value Period (NAV) Index ----------------------------------------------- 10 years 9.20% 13.35% 5 years 5.17 8.11 1 year -7.50 0.16 ----------------------------------------------- Expense Ratio (Per prospectus dated March 1, 2018) ----------------------------------------------- Gross ----------------------------------------------- 1.46% ----------------------------------------------- [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 10/08 $10,000 $10,000 10/09 $11,363 $11,452 10/10 $13,361 $14,600 10/11 $13,459 $15,452 10/12 $14,369 $17,768 10/13 $18,743 $23,711 10/14 $21,559 $27,547 10/15 $21,525 $27,675 10/16 $22,072 $29,845 10/17 $26,069 $34,953 10/18 $24,113 $35,010 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. Class 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 | Annual Report | 10/31/18 Performance Update | 10/31/18 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 October 31, 2018) ----------------------------------------------- Net Russell Asset Midcap Value Value Period (NAV) Index ----------------------------------------------- 10 years 9.96% 13.35% 5 years 5.89 8.11 1 year -6.85 0.16 ----------------------------------------------- Expense Ratio (Per prospectus dated March 1, 2018) ----------------------------------------------- Gross ----------------------------------------------- 0.81% ----------------------------------------------- [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 10/08 $ 5,000,000 $ 5,000,000 10/09 $ 5,720,459 $ 5,725,994 10/10 $ 6,776,603 $ 7,300,067 10/11 $ 6,873,861 $ 7,725,976 10/12 $ 7,386,481 $ 8,883,830 10/13 $ 9,706,336 $11,855,386 10/14 $11,248,249 $13,773,289 10/15 $11,307,573 $13,837,693 10/16 $11,673,106 $14,922,273 10/17 $13,873,487 $17,476,596 10/18 $12,923,608 $17,505,231 Call 1-800-225-6292 or visit www.amundipioneer.com for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted. The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost. Class Y shares are not subject to sales charges and are available for limited groups of 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 | Annual Report | 10/31/18 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 May 1, 2018, through October 31, 2018. -------------------------------------------------------------------------------------- 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 5/1/18 -------------------------------------------------------------------------------------- Ending Account $ 937.94 $ 934.45 $ 939.17 $ 935.67 $ 939.20 Value (after expenses) on 10/31/18 -------------------------------------------------------------------------------------- Expenses Paid $ 4.98 $ 8.92 $ 3.32 $ 7.22 $ 3.81 During Period* -------------------------------------------------------------------------------------- * Expenses are equal to the Fund's annualized expense ratio of 1.02%, 1.83%, 0.68%, 1.48%, and 0.78% multiplied by the average account value over the period, multiplied by 184/365 (to reflect the partial year period). 16 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 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 May 1, 2018, through October 31, 2018. -------------------------------------------------------------------------------------- Share Class A C K R Y -------------------------------------------------------------------------------------- Beginning Account $1,000.00 $1,000.00 $1,001.00 $1,000.00 $1,000.00 Value on 5/1/18 -------------------------------------------------------------------------------------- Ending Account $1,020.06 $1,015.98 $1,021.78 $1,017.74 $1,021.27 Value (after expenses) on 10/31/18 -------------------------------------------------------------------------------------- Expenses Paid $ 5.19 $ 9.30 $ 3.47 $ 7.53 $ 3.97 During Period* -------------------------------------------------------------------------------------- * Expenses are equal to the Fund's annualized expense ratio of 1.02%, 1.83%, 0.68%, 1.48%, and 0.78% multiplied by the average account value over the period, multiplied by 184/365 (to reflect the partial year period). Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 17 Schedule of Investments | 10/31/18 ---------------------------------------------------------------------------------------------------- Shares Value ---------------------------------------------------------------------------------------------------- UNAFFILIATED ISSUERS -- 101.4% COMMON STOCKS -- 101.2% of Net Assets AUTOMOBILES & COMPONENTS -- 1.3% Auto Parts & Equipment -- 1.1% 212,193 BorgWarner, Inc. $ 8,362,526 ---------------------------------------------------------------------------------------------------- Tires & Rubber -- 0.2% 72,753 Goodyear Tire & Rubber Co. $ 1,532,178 ------------ Total Automobiles & Components $ 9,894,704 ---------------------------------------------------------------------------------------------------- BANKS -- 11.3% Regional Banks -- 9.1% 424,036 Cathay General Bancorp $ 15,973,436 795,472 First Horizon National Corp. 12,838,918 1,409,364 Huntington Bancshares, Inc. 20,196,186 1,139,048 KeyCorp 20,685,112 ------------ $ 69,693,652 ---------------------------------------------------------------------------------------------------- Thrifts & Mortgage Finance -- 2.2% 907,222 Radian Group, Inc. $ 17,409,590 ------------ Total Banks $ 87,103,242 ---------------------------------------------------------------------------------------------------- CAPITAL GOODS -- 12.5% Aerospace & Defense -- 2.2% 476,342 BAE Systems Plc (A.D.R.) $ 12,837,417 17,007 Huntington Ingalls Industries, Inc. 3,715,689 ------------ $ 16,553,106 ---------------------------------------------------------------------------------------------------- Building Products -- 1.8% 339,505 Masco Corp. $ 10,185,150 79,939 Owens Corning 3,778,717 ------------ $ 13,963,867 ---------------------------------------------------------------------------------------------------- Industrial Conglomerates -- 1.3% 107,490 Carlisle Cos., Inc. $ 10,382,459 ---------------------------------------------------------------------------------------------------- Industrial Machinery -- 5.6% 199,709 Ingersoll-Rand Plc $ 19,160,081 108,521 Stanley Black & Decker, Inc. 12,644,867 288,800 Timken Co. 11,422,040 ------------ $ 43,226,988 ---------------------------------------------------------------------------------------------------- Trading Companies & Distributors -- 1.6% 100,663(a) United Rentals, Inc. $ 12,086,607 ------------ Total Capital Goods $ 96,213,027 ---------------------------------------------------------------------------------------------------- CONSUMER DURABLES & APPAREL -- 3.5% Homebuilding -- 2.3% 716,266 PulteGroup, Inc. $ 17,598,656 ---------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. 18 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 ---------------------------------------------------------------------------------------------------- Shares Value ---------------------------------------------------------------------------------------------------- Leisure Products -- 1.2% 172,287 Brunswick Corp. $ 8,957,201 ------------ Total Consumer Durables & Apparel $ 26,555,857 ---------------------------------------------------------------------------------------------------- CONSUMER SERVICES -- 1.5% Hotels, Resorts & Cruise Lines -- 1.5% 254,388(a) Norwegian Cruise Line Holdings, Ltd. $ 11,210,879 ------------ Total Consumer Services $ 11,210,879 ---------------------------------------------------------------------------------------------------- DIVERSIFIED FINANCIALS -- 5.4% Consumer Finance -- 3.6% 267,516 Discover Financial Services $ 18,637,840 325,172 Synchrony Financial 9,390,967 ------------ $ 28,028,807 ---------------------------------------------------------------------------------------------------- Financial Exchanges & Data -- 1.8% 156,692 Nasdaq, Inc. $ 13,586,763 ------------ Total Diversified Financials $ 41,615,570 ---------------------------------------------------------------------------------------------------- ENERGY -- 7.8% Oil & Gas Equipment & Services -- 2.0% 424,696 National Oilwell Varco, Inc. $ 15,628,813 ---------------------------------------------------------------------------------------------------- Oil & Gas Exploration & Production -- 4.4% 64,703 Devon Energy Corp. $ 2,096,377 994,327 Marathon Oil Corp. 18,882,270 403,073 Murphy Oil Corp. 12,841,906 ------------ $ 33,820,553 ---------------------------------------------------------------------------------------------------- Oil & Gas Refining & Marketing -- 1.4% 248,073 PBF Energy, Inc., Class A $ 10,381,855 ------------ Total Energy $ 59,831,221 ---------------------------------------------------------------------------------------------------- FOOD & STAPLES RETAILING -- 1.9% Food Retail -- 1.9% 482,400 Kroger Co. $ 14,356,224 ------------ Total Food & Staples Retailing $ 14,356,224 ---------------------------------------------------------------------------------------------------- FOOD, BEVERAGE & TOBACCO -- 1.1% Packaged Foods & Meats -- 1.1% 188,383 General Mills, Inc. $ 8,251,175 ------------ Total Food, Beverage & Tobacco $ 8,251,175 ---------------------------------------------------------------------------------------------------- HEALTH CARE EQUIPMENT & SERVICES -- 8.0% Health Care Equipment -- 1.8% 358,187(a) Hologic, Inc. $ 13,965,711 ---------------------------------------------------------------------------------------------------- Health Care Facilities -- 2.2% 139,744 Universal Health Services, Inc., Class B $ 16,987,281 ---------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 19 Schedule of Investments | 10/31/18 (continued) ---------------------------------------------------------------------------------------------------- Shares Value ---------------------------------------------------------------------------------------------------- Health Care Services -- 2.0% 96,589(a) Laboratory Corp. of America Holdings $ 15,507,364 ---------------------------------------------------------------------------------------------------- Managed Health Care -- 2.0% 116,162(a) Centene Corp. $ 15,138,232 ------------ Total Health Care Equipment & Services $ 61,598,588 ---------------------------------------------------------------------------------------------------- INSURANCE -- 6.6% Life & Health Insurance -- 4.2% 302,200 Lincoln National Corp. $ 18,189,418 388,321 Unum Group 14,080,519 ------------ $ 32,269,937 ---------------------------------------------------------------------------------------------------- Property & Casualty Insurance -- 2.4% 165,657 Assured Guaranty, Ltd. $ 6,622,967 543,819 Old Republic International Corp. 11,991,209 ------------ $ 18,614,176 ------------ Total Insurance $ 50,884,113 ---------------------------------------------------------------------------------------------------- MATERIALS -- 5.8% Copper -- 1.2% 798,496 Freeport-McMoRan, Inc. $ 9,302,478 ---------------------------------------------------------------------------------------------------- Fertilizers & Agricultural Chemicals -- 2.7% 671,688 Mosaic Co. $ 20,782,027 ---------------------------------------------------------------------------------------------------- Specialty Chemicals -- 1.9% 147,375 Celanese Corp. $ 14,286,533 ------------ Total Materials $ 44,371,038 ---------------------------------------------------------------------------------------------------- PHARMACEUTICALS, BIOTECHNOLOGY & LIFE SCIENCES -- 1.8% Pharmaceuticals -- 1.8% 87,609(a) Jazz Pharmaceuticals Plc $ 13,914,061 ------------ Total Pharmaceuticals, Biotechnology & Life Sciences $ 13,914,061 ---------------------------------------------------------------------------------------------------- REAL ESTATE -- 9.3% Hotel & Resorts REIT -- 1.7% 453,579 Park Hotels & Resorts, Inc. $ 13,185,542 ---------------------------------------------------------------------------------------------------- Industrial REIT -- 1.6% 454,450 Duke Realty Corp. $ 12,529,186 ---------------------------------------------------------------------------------------------------- Residential REIT -- 2.0% 580,415 American Homes 4 Rent, Class A $ 12,229,344 28,675 Sun Communities, Inc. 2,880,977 ------------ $ 15,110,321 ---------------------------------------------------------------------------------------------------- Specialized REIT -- 4.0% 130,431 Digital Realty Trust, Inc. $ 13,468,305 409,959 Gaming & Leisure Properties, Inc. 13,811,519 The accompanying notes are an integral part of these financial statements. 20 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 ---------------------------------------------------------------------------------------------------- Shares Value ---------------------------------------------------------------------------------------------------- Specialized REIT -- (continued) 177,566 VICI Properties, Inc. $ 3,833,650 ------------ $ 31,113,474 ------------ Total Real Estate $ 71,938,523 ---------------------------------------------------------------------------------------------------- RETAILING -- 4.7% Department Stores -- 0.7% 70,185 Kohl's Corp. $ 5,315,110 ---------------------------------------------------------------------------------------------------- General Merchandise Stores -- 2.2% 153,670 Dollar General Corp. $ 17,115,765 ---------------------------------------------------------------------------------------------------- Homefurnishing Retail -- 0.7% 114,164 Aaron's, Inc. $ 5,380,549 ---------------------------------------------------------------------------------------------------- Specialty Stores -- 1.1% 227,234 Dick's Sporting Goods, Inc. $ 8,037,267 ------------ Total Retailing $ 35,848,691 ---------------------------------------------------------------------------------------------------- SEMICONDUCTORS & SEMICONDUCTOR EQUIPMENT -- 2.8% Semiconductors -- 2.8% 610,167 Marvell Technology Group, Ltd. $ 10,012,840 660,616(a) ON Semiconductor Corp. 11,230,472 ------------ Total Semiconductors & Semiconductor Equipment $ 21,243,312 ---------------------------------------------------------------------------------------------------- SOFTWARE & SERVICES -- 3.5% IT Consulting & Other Services -- 3.5% 199,100 Booz Allen Hamilton Holding Corp. $ 9,863,414 233,195 DXC Technology Co. 16,983,592 ------------ Total Software & Services $ 26,847,006 ---------------------------------------------------------------------------------------------------- TECHNOLOGY HARDWARE & EQUIPMENT -- 3.0% Communications Equipment -- 1.0% 60,949 Motorola Solutions, Inc. $ 7,469,909 ---------------------------------------------------------------------------------------------------- Technology Distributors -- 2.0% 172,182 CDW Corp. $ 15,498,102 ------------ Total Technology Hardware & Equipment $ 22,968,011 ---------------------------------------------------------------------------------------------------- TELECOMMUNICATION SERVICES -- 1.9% Integrated Telecommunication Services -- 1.9% 723,913 CenturyLink, Inc. $ 14,941,564 ------------ Total Telecommunication Services $ 14,941,564 ---------------------------------------------------------------------------------------------------- TRANSPORTATION -- 3.1% Airlines -- 1.7% 153,636(a) United Continental Holdings, Inc. $ 13,137,415 ---------------------------------------------------------------------------------------------------- Railroads -- 1.4% 108,494 Kansas City Southern $ 11,062,048 ------------ Total Transportation $ 24,199,463 ---------------------------------------------------------------------------------------------------- The accompanying notes are an integral part of these financial statements. Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 21 Schedule of Investments | 10/31/18 (continued) ----------------------------------------------------------------------------------------------------- Shares Value ----------------------------------------------------------------------------------------------------- UTILITIES -- 4.4% Electric Utilities -- 2.2% 202,430 Entergy Corp. $ 16,993,998 ----------------------------------------------------------------------------------------------------- Multi-Utilities -- 2.2% 322,492 Public Service Enterprise Group, Inc. $ 17,230,748 ------------- Total Utilities $ 34,224,746 ----------------------------------------------------------------------------------------------------- TOTAL COMMON STOCKS (Cost $737,998,935) $778,011,015 ----------------------------------------------------------------------------------------------------- ----------------------------------------------------------------------------------------------------- Principal Amount USD ($) ----------------------------------------------------------------------------------------------------- TEMPORARY CASH INVESTMENTS -- 0.2% of Net Assets Repurchase Agreement -- 0.2% 1,295,000 $1,295,000 ScotiaBank, 2.20%, dated 10/31/18 plus accrued interest on 11/1/18 collateralized by $1,320,981 Freddie Mac Giant, 3.5%, 12/1/47 $ 1,295,000 ----------------------------------------------------------------------------------------------------- TOTAL TEMPORARY CASH INVESTMENTS (Cost $1,295,000) $ 1,295,000 ----------------------------------------------------------------------------------------------------- TOTAL INVESTMENTS IN UNAFFILIATED ISSUERS -- 101.4% (Cost $739,293,935) $779,306,015 ----------------------------------------------------------------------------------------------------- OTHER ASSETS AND LIABILITIES -- (1.4)% $(10,995,988) ----------------------------------------------------------------------------------------------------- NET ASSETS -- 100.0% $768,310,027 ===================================================================================================== REIT Real Estate Investment Trust. (A.D.R.) American Depositary Receipts. (a) Non-income producing security. Purchases and sales of securities (excluding temporary cash investments) for the year ended October 31, 2018, aggregated $702,605,090 and $829,712,938, 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., formerly Pioneer Investment 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 year ended October 31, 2018, the Fund did not engage in cross trade activity. At October 31, 2018, the net unrealized appreciation on investments based on cost for federal tax purposes of $742,204,238 was as follows: Aggregate gross unrealized appreciation for all investments in which there is an excess of value over tax cost $ 79,304,581 Aggregate gross unrealized depreciation for all investments in which there is an excess of tax cost over value (42,202,804) ------------ Net unrealized appreciation $ 37,101,777 ============ The accompanying notes are an integral part of these financial statements. 22 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 Various inputs are used in determining the value of the Fund's investments. These inputs are summarized in the three broad levels below. Level 1 - quoted prices in active markets for identical securities. Level 2 - other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risks, etc.). See Notes to Financial Statements -- Note 1A. Level 3 - significant unobservable inputs (including the Fund's own assumptions in determining fair value of investments). See Notes to Financial Statements -- Note 1A. The following is a summary of the inputs used as of October 31, 2018, in valuing the Fund's investments. -------------------------------------------------------------------------------------- Level 1 Level 2 Level 3 Total -------------------------------------------------------------------------------------- Common Stocks $778,011,015 $ -- $ -- $778,011,015 Repurchase Agreement -- 1,295,000 -- 1,295,000 -------------------------------------------------------------------------------------- Total Investments in Securities $778,011,015 $1,295,000 $ -- $779,306,015 ====================================================================================== During the year ended October 31, 2018, 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 | Annual Report | 10/31/18 23 Statement of Assets and Liabilities | 10/31/18 ASSETS: Investments in unaffiliated issuers, at value (cost $739,293,935) $779,306,015 Cash 688,855 Receivables -- Investment securities sold 17,619,851 Fund shares sold 64,189 Dividends 756,329 Interest 79 Other assets 28,345 -------------------------------------------------------------------------------------------- Total assets $798,463,663 ============================================================================================ LIABILITIES: Payables -- Investment securities purchased $ 29,217,744 Fund shares repurchased 596,013 Distributions 2,470 Trustees' fees 4,556 Due to affiliates 84,514 Accrued expenses 248,339 -------------------------------------------------------------------------------------------- Total liabilities $ 30,153,636 ============================================================================================ NET ASSETS: Paid-in capital $656,576,959 Distributable earnings 111,733,068 -------------------------------------------------------------------------------------------- Net assets $768,310,027 ============================================================================================ NET ASSET VALUE PER SHARE: No par value (unlimited number of shares authorized) Class A (based on $710,468,092/31,572,620 shares) $ 22.50 Class C (based on $18,495,344/1,191,228 shares) $ 15.53 Class K (based on $1,692,681/75,014 shares) $ 22.56 Class R (based on $10,243,704/466,892 shares) $ 21.94 Class Y (based on $27,410,206/1,129,747 shares) $ 24.26 MAXIMUM OFFERING PRICE PER SHARE: Class A (based on $22.50 net asset value per share/100%-5.75% maximum sales charge) $ 23.87 ============================================================================================ The accompanying notes are an integral part of these financial statements. 24 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 Statement of Operations For the Year Ended 10/31/18 INVESTMENT INCOME: Dividends from unaffiliated issuers $14,911,880 Interest from unaffiliated issuers 20,531 ------------------------------------------------------------------------------------------------------- Total investment income $ 14,932,411 ======================================================================================================= EXPENSES: Management fees Basic fee $ 6,143,068 Performance Adjustment (753,531) Administrative expense 361,468 Transfer agent fees Class A 577,720 Class C 52,238 Class K 107 Class R 36,674 Class Y 32,262 Distribution fees Class A 2,019,529 Class C 421,908 Class R 62,899 Shareowner communications expense 208,355 Custodian fees 26,562 Registration fees 93,870 Professional fees 88,395 Printing expense 28,113 Trustees' fees 38,949 Insurance expense 6,234 Miscellaneous 86,068 ------------------------------------------------------------------------------------------------------- Total expenses $ 9,530,888 ------------------------------------------------------------------------------------------------------- Net investment income $ 5,401,523 ------------------------------------------------------------------------------------------------------- REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS: Net realized gain (loss) on: Investments in unaffiliated issuers $71,268,447 Class actions 114,222 $ 71,382,669 ------------------------------------------------------------------------------------------------------- Change in net unrealized appreciation (depreciation) on: Investments in unaffiliated issuers $(132,465,402) ------------------------------------------------------------------------------------------------------- Net realized and unrealized gain (loss) on investments $ (61,082,733) ------------------------------------------------------------------------------------------------------- Net decrease in net assets resulting from operations $ (55,681,210) ======================================================================================================= The accompanying notes are an integral part of these financial statements. Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 25 Statements of Changes in Net Assets -------------------------------------------------------------------------------------------------------------------- Year Year Ended Ended 10/31/18 10/31/17 -------------------------------------------------------------------------------------------------------------------- FROM OPERATIONS: Net investment income (loss) $ 5,401,523 $ 3,813,398 Net realized gain (loss) on investments 71,382,669 71,962,541 Change in net unrealized appreciation (depreciation) on investments (132,465,402) 86,725,827 -------------------------------------------------------------------------------------------------------------------- Net increase (decrease) in net assets resulting from operations $ (55,681,210) $ 162,501,766 -------------------------------------------------------------------------------------------------------------------- DISTRIBUTIONS TO SHAREOWNERS: Class A ($2.11 and $1.60 per share, respectively) $ (66,998,046) $ (53,232,710)** Class C ($2.02 and $1.49 per share, respectively) (5,168,871) (4,384,884)** Class K ($2.20 and $1.68 per share, respectively) (2,233,949) (1,045,578)** Class R ($2.02 and $1.50 per share, respectively) (1,109,167) (1,005,272)** Class Y ($2.16 and $1.65 per share, respectively) (2,918,223) (2,229,496)** -------------------------------------------------------------------------------------------------------------------- Total distributions to shareowners $ (78,428,256) $ (61,897,940) -------------------------------------------------------------------------------------------------------------------- FROM FUND SHARE TRANSACTIONS: Net proceeds from sales of shares $ 60,974,927 $ 79,105,275 Reinvestment of distributions 73,099,899 57,913,688 Cost of shares repurchased (200,505,997) (173,483,218) -------------------------------------------------------------------------------------------------------------------- Net decrease in net assets resulting from Fund share transactions $ (66,431,171) $ (36,464,255) -------------------------------------------------------------------------------------------------------------------- Net increase (decrease) in net assets $(200,540,637) $ 64,139,571 NET ASSETS:* Beginning of year $ 968,850,664 $ 904,711,093 -------------------------------------------------------------------------------------------------------------------- End of year $ 768,310,027 $ 968,850,664 ==================================================================================================================== **For the year ended October 31, 2017, distributions to shareowners were presented as follows: Net investment income: Class A ($0.11 per share) $ (3,667,622) Class K ($0.19 per share) (245,527) Class R ($0.01 per share) (8,981) Class Y ($0.16 per share) (234,328) Net realized gain: Class A ($1.49 per share) $ (49,565,088) Class C ($1.49 per share) (4,384,884) Class K ($1.49 per share) (800,051) Class R ($1.49 per share) (996,291) Class Y ($1.49 per share) (1,995,168) * For the year ended October 31, 2017 undistributed net investment income was presented as follows: $1,350,587 The accompanying notes are an integral part of these financial statements. 26 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 ---------------------------------------------------------------------------------------------------- Year Ended Year Ended Year Ended Year Ended 10/31/18 10/31/18 10/31/17 10/31/17 Shares Amount Shares Amount ---------------------------------------------------------------------------------------------------- Class A Shares sold 1,684,495 $ 41,686,775 1,217,028 $ 30,386,403 Reinvestment of distributions 2,588,720 64,283,020 2,155,831 51,076,411 Less shares repurchased (4,656,638) (115,614,113) (4,869,055) (121,958,030) ---------------------------------------------------------------------------------------------------- Net decrease (383,423) $ (9,644,318) (1,496,196) $ (40,495,216) ==================================================================================================== Class C Shares sold 236,324 $ 4,059,736 425,459 $ 7,613,633 Reinvestment of distributions 288,609 4,958,299 229,045 3,886,900 Less shares repurchased (1,928,864) (33,241,582) (1,024,643) (18,383,981) ---------------------------------------------------------------------------------------------------- Net decrease (1,403,931) $ (24,223,547) (370,139) $ (6,883,448) ==================================================================================================== Class K Shares sold 196,793 $ 4,985,892 813,330 $ 20,108,475 Reinvestment of distributions 5,210 129,819 -- -- Less shares repurchased (1,128,285) (27,878,904) (347,257) (8,667,713) ---------------------------------------------------------------------------------------------------- Net increase (decrease) (926,282) $ (22,763,193) 466,073 $ 11,440,762 ==================================================================================================== Class R Shares sold 65,576 $ 1,571,662 104,143 $ 2,568,276 Reinvestment of distributions 44,593 1,079,604 42,708 986,974 Less shares repurchased (210,664) (5,171,255) (246,466) (6,075,840) ---------------------------------------------------------------------------------------------------- Net decrease (100,495) $ (2,519,989) (99,615) $ (2,520,590) ==================================================================================================== Class Y Shares sold 325,163 $ 8,670,862 687,079 $ 18,428,488 Reinvestment of distributions 98,942 2,649,157 77,256 1,963,403 Less shares repurchased (694,425) (18,600,143) (684,704) (18,397,654) ---------------------------------------------------------------------------------------------------- Net increase (decrease) (270,320) $ (7,280,124) 79,631 $ 1,994,237 ==================================================================================================== The accompanying notes are an integral part of these financial statements. Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 27 Financial Highlights ------------------------------------------------------------------------------------------------------------------------------------ Year Year Year Year Year Ended Ended Ended Ended Ended 10/31/18 10/31/17 10/31/16* 10/31/15* 10/31/14* ------------------------------------------------------------------------------------------------------------------------------------ Class A Net asset value, beginning of period $ 26.27 $ 23.66 $ 25.30 $ 28.37 $ 27.42 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.16(a) $ 0.11(a) $ 0.12(a) $ 0.14(a) $ 0.15 Net realized and unrealized gain (loss) on investments (1.82) 4.10 0.58 (0.01) 3.71 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ (1.66) $ 4.21 $ 0.70 $ 0.13 $ 3.86 ------------------------------------------------------------------------------------------------------------------------------------ Distributions to shareowners: Net investment income $ (0.09) $ (0.11) $ (0.08) $ (0.11) $ (0.11) Net realized gain (2.02) (1.49) (2.26) (3.09) (2.80) ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $ (2.11) $ (1.60) $ (2.34) $ (3.20) $ (2.91) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ (3.77) $ 2.61 $ (1.64) $ (3.07) $ 0.95 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 22.50 $ 26.27 $ 23.66 $ 25.30 $ 28.37 ==================================================================================================================================== Total return (b) (7.05)% 18.56% 2.94% 0.22% 15.47% Ratio of net expenses to average net assets 1.02% 1.04% 1.08% 1.05% 1.04% Ratio of net investment income (loss) to average net assets 0.63% 0.43% 0.53% 0.54% 0.58% Portfolio turnover rate 78% 58% 70% 90% 61% Net assets, end of period (in thousands) $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. The accompanying notes are an integral part of these financial statements. 28 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 ------------------------------------------------------------------------------------------------------------------------------------ Year Year Year Year Year Ended Ended Ended Ended Ended 10/31/18 10/31/17 10/31/16* 10/31/15* 10/31/14* ------------------------------------------------------------------------------------------------------------------------------------ Class C Net asset value, beginning of period $ 18.82 $ 17.42 $ 19.29 $ 22.42 $ 22.33 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ (0.03)(a) $ (0.07)(a) $ (0.05)(a)(b) $ (0.06)(a) $ (0.05) Net realized and unrealized gain (loss) on investments (1.24) 2.96 0.44 0.02 2.94 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ (1.27) $ 2.89 $ 0.39 $ (0.04) $ 2.89 ------------------------------------------------------------------------------------------------------------------------------------ Distributions to shareowners: Net investment income $ -- $ -- $ -- $ -- $ -- Net realized gain (2.02) (1.49) (2.26) (3.09) (2.80) ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $ (2.02) $ (1.49) $ (2.26) $ (3.09) $ (2.80) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ (3.29) $ 1.40 $ (1.87) $ (3.13) $ 0.09 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 15.53 $ 18.82 $ 17.42 $ 19.29 $ 22.42 ==================================================================================================================================== Total return (c) (7.77)%(d) 17.55% 2.13% (0.59)% 14.50% Ratio of net expenses to average net assets 1.83% 1.87% 1.92% 1.90% 1.86% Ratio of net investment income (loss) to average net assets (0.15)% (0.40)% (0.30)% (0.31)% (0.24)% Portfolio turnover rate 78% 58% 70% 90% 61% Net assets, end of period (in thousands) $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) 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)%. The accompanying notes are an integral part of these financial statements. Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 29 Financial Highlights (continued) ------------------------------------------------------------------------------------------------------------------------------------ Year Year Year Ended Ended Ended 3/2/15 to 10/31/18 10/31/17 10/31/16* 10/31/15* ------------------------------------------------------------------------------------------------------------------------------------ Class K Net asset value, beginning of period $26.34 $ 23.72 $ 25.37 $ 26.76 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.21(a) $ 0.19(a) $ 0.21(a) $ 0.15(a) Net realized and unrealized gain (loss) on investments (1.79) 4.11 0.58 (1.54) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $(1.58) $ 4.30 $ 0.79 $ (1.39) ------------------------------------------------------------------------------------------------------------------------------------ Distributions to shareowners: Net investment income $(0.18) $ (0.19) $ (0.18) $ -- Net realized gain (2.02) (1.49) (2.26) -- ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $(2.20) $ (1.68) $ (2.44) $ -- ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $(3.78) $ 2.62 $ (1.65) $ (1.39) ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $22.56 $ 26.34 $ 23.72 $ 25.37 ==================================================================================================================================== Total return (b) (6.75)%(c) 18.98% 3.36% (5.19)%(d) Ratio of net expenses to average net assets 0.68% 0.68% 0.71% 0.65%(e) Ratio of net investment income (loss) to average net assets 0.83% 0.74% 0.91% 0.85%(e) Portfolio turnover rate 78% 58% 70% 0.90% Net assets, end of period (in thousands) $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 and reinvestment of all distributions and the complete redemption of the investment at net asset value at the end of each period. (c) 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)%. (d) Not Annualized. (e) Annualized. The accompanying notes are an integral part of these financial statements. 30 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 ------------------------------------------------------------------------------------------------------------------------------------ Year Year Year Year Year Ended Ended Ended Ended Ended 10/31/18 10/31/17 10/31/16* 10/31/15* 10/31/14* ------------------------------------------------------------------------------------------------------------------------------------ Class R Net asset value, beginning of period $ 25.70 $ 23.18 $ 24.84 $ 27.91 $ 27.02 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.04(a) $ 0.00(a)(b) $ 0.03(a) $ 0.04(a) $ 0.07 Net realized and unrealized gain (loss) on investments (1.78) 4.02 0.57 0.00(b) 3.63 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ (1.74) $ 4.02 $ 0.60 $ 0.04 $ 3.70 ------------------------------------------------------------------------------------------------------------------------------------ Distributions to shareowners: Net investment income $ -- $ (0.01) $ -- $ (0.02) $ (0.01) Net realized gain (2.02) (1.49) (2.26) (3.09) (2.80) ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $ (2.02) $ (1.50) $ (2.26) $ (3.11) $ (2.81) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ (3.76) $ 2.52 $ (1.66) $ (3.07) $ 0.89 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 21.94 $ 25.70 $ 23.18 $ 24.84 $ 27.91 ==================================================================================================================================== Total return (c) (7.50)% 18.11% 2.54% (0.16)% 15.03% Ratio of net expenses to average net assets 1.48% 1.46% 1.47% 1.44% 1.43% Ratio of net investment income (loss) to average net assets 0.18% 0.02% 0.15% 0.16% 0.20% Portfolio turnover rate 78% 58% 70% 90% 61% Net assets, end of period (in thousands) $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. The accompanying notes are an integral part of these financial statements. Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 31 Financial Highlights (continued) ------------------------------------------------------------------------------------------------------------------------------------ Year Year Year Year Year Ended Ended Ended Ended Ended 10/31/18 10/31/17 10/31/16* 10/31/15* 10/31/14* ------------------------------------------------------------------------------------------------------------------------------------ Class Y Net asset value, beginning of period $ 28.16 $ 25.25 $ 26.84 $ 29.91 $ 28.74 ------------------------------------------------------------------------------------------------------------------------------------ Increase (decrease) from investment operations: Net investment income (loss) $ 0.23(a) $ 0.18(a) $ 0.19(a) $ 0.25(a) $ 0.29 Net realized and unrealized gain (loss) on investments (1.97) 4.38 0.63 (0.02) 3.87 ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) from investment operations $ (1.74) $ 4.56 $ 0.82 $ 0.23 $ 4.16 ------------------------------------------------------------------------------------------------------------------------------------ Distributions to shareowners: Net investment income $ (0.14) $ (0.16) $ (0.15) $ (0.21) $ (0.19) Net realized gain (2.02) (1.49) (2.26) (3.09) (2.80) ------------------------------------------------------------------------------------------------------------------------------------ Total distributions $ (2.16) $ (1.65) $ (2.41) $ (3.30) $ (2.99) ------------------------------------------------------------------------------------------------------------------------------------ Net increase (decrease) in net asset value $ (3.90) $ 2.91 $ (1.59) $ (3.07) $ 1.17 ------------------------------------------------------------------------------------------------------------------------------------ Net asset value, end of period $ 24.26 $ 28.16 $ 25.25 $ 26.84 $ 29.91 ==================================================================================================================================== Total return (b) (6.85)% 18.85% 3.23% 0.53% 15.89% Ratio of net expenses to average net assets 0.78% 0.81% 0.82% 0.73% 0.67% Ratio of net investment income (loss) to average net assets 0.88% 0.66% 0.79% 0.90% 0.95% Portfolio turnover rate 78% 58% 70% 90% 61% Net assets, end of period (in thousands) $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. The accompanying notes are an integral part of these financial statements. 32 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 Notes to Financial Statements | 10/31/18 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 six classes of shares designated as Class A, Class C, Class K, Class R, Class T and Class Y shares. Class T shares had not commenced operations as of October 31, 2018. 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 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 | Annual Report | 10/31/18 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. The value of foreign securities is translated into U.S. dollars based on foreign currency exchange rate quotations supplied by a third party pricing source. Trading in non-U.S. equity securities is substantially completed each day at various times prior to the close of the NYSE. The values of such securities used in computing the net asset value of the Fund's shares are determined as of such times. The fund may use a fair value model developed by an independent pricing service to value non-U.S. equity securities. Securities for which independent pricing services or broker-dealers are unable to supply prices or for which market prices and/or quotations are not readily available or are considered to be unreliable are valued by a fair valuation team comprised of certain personnel of the Adviser pursuant to procedures adopted by the Fund's Board of Trustees. The Adviser's fair valuation team uses fair value methods approved by the Valuation Committee of the Board of Trustees. The Adviser's fair valuation team is responsible for monitoring developments that may impact fair valued securities and for discussing and assessing fair values on an ongoing basis, and at least quarterly, with the Valuation Committee of the Board of Trustees. Inputs used when applying fair value methods to value a security may include credit ratings, the financial condition of the company, current market conditions and comparable securities. The Fund may use fair value methods if it is determined that a significant event has occurred after the close of the 34 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 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 October 31, 2018, 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 October 31, 2018, the Fund did not accrue any interest or penalties with respect to uncertain tax positions, which, if applicable, would be recorded as an income tax expense on the Statement of Operations. Tax returns filed within the prior three years remain subject to examination by federal and state tax authorities. The amount and character of income and capital gain distributions to shareowners are determined in accordance with federal income tax rules, which may differ from U.S. GAAP. Distributions in excess of net investment income or net realized gains are temporary over distributions for financial Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 35 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. At October 31, 2018, the Fund reclassified $170,094 to decrease distributable earnings and $170,094 to increase paid-in capital to reflect permanent book/tax differences. These adjustments have no impact on net assets or the results of operations. The tax character of distributions paid during the years ended October 31, 2018 and October 31, 2017, were as follows: -------------------------------------------------------------------------- 2018 2017 -------------------------------------------------------------------------- Distributions paid from: Ordinary income $ 3,375,935 $ 4,156,458 Long-term capital gain 75,052,321 57,741,482 -------------------------------------------------------------------------- Total $78,428,256 $61,897,940 ========================================================================== The following shows the components of distributable earnings 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 $32,081 in underwriting commissions on the sale of Class A shares during the year ended October 31, 2018. 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 | Annual Report | 10/31/18 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 | Annual Report | 10/31/18 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 shareowners 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 year ended, the aggregate performance adjustment resulted in a decrease of $753,531 to the basic fee. For the year ended October 31, 2018 the net management fee was equivalent to 0.59% 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 $45,738 in management fees, administrative costs and certain other reimbursements payable to the Adviser at October 31, 2018. 38 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 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 year ended October 31, 2018, such out-of-pocket expenses by class of shares were as follows: -------------------------------------------------------------------------------- Shareowner Communications: -------------------------------------------------------------------------------- Class A $191,673 Class C 13,063 Class K 75 Class R 1,379 Class Y 2,165 -------------------------------------------------------------------------------- Total $208,355 ================================================================================ 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 $38,776 in distribution fees payable to the Distributor at October 31, 2018. 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 | Annual Report | 10/31/18 39 In addition, redemptions of each class of 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 R or Class Y shares. Proceeds from the CDSCs are paid to the Distributor. For the year ended October 31, 2018, CDSCs in the amount of $2,375 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 credit facility, depending on the type of loan, interest on borrowings is payable at the London Interbank Offered Rate ("LIBOR") plus 0.90% on an annualized basis, or the Alternate Base Rate, which is the greater of (a) the facility's administrative agent's daily announced prime rate on the borrowing date, (b) 2% plus the Federal Funds Rate on the borrowing date or (c) 2% plus the overnight Eurodollar rate on the borrowing date. The Funds pay an annual commitment fee to participate in a credit facility. The commitment fee is allocated among participating Funds based on an allocation schedule set forth in the credit agreement. For the year ended October 31, 2018, the Fund had no borrowings under the credit facility. 40 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 Report of Independent Registered Public Accounting Firm To the Board of Trustees and the Shareholders of Pioneer Mid Cap Value Fund: -------------------------------------------------------------------------------- Opinion on the Financial Statements We have audited the accompanying statement of assets and liabilities of Pioneer Mid Cap Value Fund (the "Fund"), including the schedule of investments, as of October 31, 2018, and the related statements of operations, changes in net assets and the financial highlights for the year then ended and the related notes, and the statement of changes in net assets and the financial highlights for the year ended October 31, 2017 (collectively referred to as the "financial statements"). The financial highlights for periods ended October 31, 2014, October 31, 2015 and October 31, 2016 were audited by another independent registered public accounting firm whose report, dated December 23, 2016, expressed an unqualified opinion on those financial highlights. In our opinion, the financial statements present fairly, in all material respects, the financial position of the Fund at October 31, 2018, the results of its operations, the changes in its net assets, and the financial highlights for the year ended, and the statement of changes in net assets and the financial highlights for the year ended October 31, 2017, in conformity with U.S. generally accepted accounting principles. Basis for Opinion These financial statements are the responsibility of the Fund's management. Our responsibility is to express an opinion on the Fund's financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) ("PCAOB") and are required to be independent with respect to the Fund in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB. We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Fund is not required to have, nor were we engaged to perform, an audit of the Fund's internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting, but not for the purpose of expressing an opinion on the effectiveness of the Fund's internal control over financial reporting. Accordingly, we express no such opinion. Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 41 Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our procedures included confirmation of securities owned as of October 31, 2018, by correspondence with the custodian and brokers. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion. /s/ Ernst & Young LLP We have served as the Fund's auditor since 2017. Boston, Massachusetts December 21, 2018 42 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 Additional Information (unaudited) Change in Independent Registered Public Accounting Firm Prior to July 3, 2017 Pioneer Investment Management, Inc. (the "Adviser"), the Fund's investment adviser, was an indirect, wholly owned subsidiary of UniCredit S.p.A. ("UniCredit"). On that date, UniCredit completed the sale of its Pioneer Investments business, which includes the Adviser, to Amundi (the "Transaction"). As a result of the Transaction, the Adviser became an indirect, wholly owned subsidiary of Amundi. Amundi is controlled by Credit Agricole S.A. Amundi is headquartered in Paris, France, and, as of September 30, 2016, had more than $1.1 trillion in assets under management worldwide. Deloitte & Touche LLP ("D&T"), the Fund's previous independent registered public accounting firm, informed the Audit Committee and the Board that it would no longer be independent with respect to the Fund upon the completion of the Transaction as a result of certain services being provided to Amundi and Credit Agricole, and, accordingly, that it intended to resign as the Fund's independent registered public accounting firm upon the completion of the Transaction. D&T's resignation was effective on July 3, 2017, when the Transaction was completed. During the periods as to which D&T has served as the Fund's independent registered public accounting firm, including the Fund's two most recent fiscal years, D&T's reports on the Fund's financial statements have not contained an adverse opinion or disclaimer of opinion and have not been qualified or modified as to uncertainty, audit scope or accounting principles. Further, there have been no disagreements with D&T on any matter of accounting principles or practices, financial statement disclosure, or auditing scope or procedure, which, if not resolved to the satisfaction of D&T, would have caused D&T to make reference to the subject matter of the disagreement in connection with its report on the financial statements. In addition, there have been no reportable events of the kind described in Item 304(a)(1)(v) of Regulation S-K under the Securities Exchange Act of 1934. Effective immediately following the completion of the Transaction on July 3, 2017, the Board, acting upon the recommendation of the Audit Committee, engaged a new independent registered public accounting firm, Ernst & Young LLP ("EY"). Prior to its engagement, EY had advised the Fund's Audit Committee that EY had identified the following matters, in each case relating to services rendered by other member firms of Ernst & Young Global Limited, all of which are located outside the United States, to UniCredit and certain of its subsidiaries Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 43 during the period commencing July 1, 2016, that it determined to be inconsistent with the auditor independence rules set forth by the Securities and Exchange Commission ("SEC"): (a) project management support services to UniCredit in the Czech Republic, Germany, Italy, Serbia and Slovenia in relation to twenty-two projects, that were determined to be inconsistent with Rule 2-01(c)(4)(vi) of Regulation S-X (management functions); (b) two engagements for UniCredit in Italy where fees were contingent/success based and that were determined to be inconsistent with Rule 2-01(c)(5) of Regulation S-X (contingent fees); (c) four engagements where legal and expert services were provided to UniCredit in the Czech Republic and Germany, and twenty engagements where the legal advisory services were provided to UniCredit in Austria, Czech Republic, Italy and Poland, that were determined to be inconsistent with Rule 2-01(c)(4)(ix) and (x) of Regulation S-X (legal and expert services); and (d) two engagements for UniCredit in Italy involving assistance in the sale of certain assets, that were determined to be inconsistent with Rule 2-01(c)(4)(viii) of Regulation S-X (broker-dealer, investment adviser or investment banking services). None of the foregoing services involved the Fund, any of the other funds in the Pioneer Family of Funds or any other Pioneer entity sold by UniCredit in the Transaction. EY advised the Audit Committee that it had considered the matters described above and had concluded that such matters would not impair EY's ability to exercise objective and impartial judgment in connection with the audits of the financial statements of the Fund under the SEC and Public Company Accounting Oversight Board independence rules, and that a reasonable investor with knowledge of all relevant facts and circumstances would reach the same conclusion. Management and the Audit Committee considered these matters and discussed the matters with EY and, based upon EY's description of the matters and statements made by EY, Management and the Audit Committee believe that EY will be capable of exercising objective and impartial judgment in connection with the audits of the financial statements of the Fund, and Management further believes that a reasonable investor with knowledge of all relevant facts and circumstances would reach the same conclusion. 44 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 Approval of Investment Management Agreement Amundi Pioneer Asset Management, Inc. ("APAM") serves as the investment adviser to Pioneer Mid Cap Value Fund (the "Fund") pursuant to an investment management agreement between APAM and the Fund. In order for APAM to remain the investment adviser of the Fund, the Trustees of the Fund must determine annually whether to renew the investment management agreement for the Fund. The contract review process began in January 2018 as the Trustees of the Fund agreed on, among other things, an overall approach and timeline for the process. Contract review materials were provided to the Trustees in March 2018, July 2018 and September 2018. In addition, the Trustees reviewed and discussed the Fund's performance at regularly scheduled meetings throughout the year, and took into account other information related to the Fund provided to the Trustees at regularly scheduled meetings, in connection with the review of the Fund's investment management agreement. In March 2018, the Trustees, among other things, discussed the memorandum provided by Fund counsel that summarized the legal standards and other considerations that are relevant to the Trustees in their deliberations regarding the renewal of the investment management agreement, and reviewed and discussed the qualifications of the investment management teams for the Fund, as well as the level of investment by the Fund's portfolio managers in the Fund. In July 2018, the Trustees, among other things, reviewed the Fund's management fees and total expense ratios, the financial statements of APAM and its parent companies, profitability analyses provided by APAM, and analyses from APAM as to possible economies of scale. The Trustees also reviewed the profitability of the institutional business of APAM and APAM's affiliate, Amundi Pioneer Institutional Asset Management, Inc. ("APIAM" and, together with APAM, "Amundi Pioneer"), as compared to that of APAM's fund management business, and considered the differences between the fees and expenses of the Fund and the fees and expenses of APAM's and APIAM's institutional accounts, as well as the different services provided by APAM to the Fund and by APAM and APIAM to the institutional accounts. The Trustees further considered contract review materials, including additional materials received in response to the Trustees' request, in September 2018. At a meeting held on September 18, 2018, based on their evaluation of the information provided by APAM and third parties, the Trustees of the Fund, including the Independent Trustees voting separately, unanimously approved the renewal of the investment management agreement for another year. In approving the renewal of the investment management agreement, the Trustees Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 45 considered various factors that they determined were relevant, including the factors described below. The Trustees did not identify any single factor as the controlling factor in determining to approve the renewal of the agreement. Nature, Extent and Quality of Services The Trustees considered the nature, extent and quality of the services that had been provided by APAM to the Fund, taking into account the investment objective and strategy of the Fund. The Trustees also reviewed APAM's investment approach for the Fund and its research process. The Trustees considered the resources of APAM and the personnel of APAM who provide investment management services to the Fund. They also reviewed the amount of non-Fund assets managed by the portfolio managers of the Fund. They considered the non-investment resources and personnel of APAM that are involved in APAM's services to the Fund, including APAM's compliance, risk management, and legal resources and personnel. The Trustees noted the substantial attention and high priority given by APAM's senior management to the Pioneer Fund complex. The Trustees considered that APAM supervises and monitors the performance of the Fund's service providers and provides the Fund with personnel (including Fund officers) and other resources that are necessary for the Fund's business management and operations. The Trustees also considered that, as administrator, APAM is responsible for the administration of the Fund's business and other affairs. The Trustees considered the fees paid to APAM for the provision of administration services. Based on these considerations, the Trustees concluded that the nature, extent and quality of services that had been provided by APAM to the Fund were satisfactory and consistent with the terms of the investment management agreement. Performance of the Fund In considering the Fund's performance, the Trustees regularly review and discuss throughout the year data prepared by APAM and information comparing the Fund's performance with the performance of its peer group of funds, as classified by Morningstar, Inc. (Morningstar), and the performance of the Fund's benchmark index. They also discuss the Fund's performance with APAM on a regular basis. The Trustees discussed the Fund's performance with APAM on a more frequent basis in light of the Fund's unfavorable performance compared to its benchmark index and peers over certain periods. The Trustees noted APAM's explanation for the Fund's relative performance and the steps taken by APAM to address the Fund's performance, including enhancing the investment 46 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 process used for the Fund. It was noted that Raymond Haddad a Vice President of APAM, became a portfolio manager of the Fund in March 2018, and Timothy P. Stanish, a Vice President of APAM, also became a portfolio manager of the Fund in September 2018. The Trustees' regular reviews and discussions were factored into the Trustees' deliberations concerning the renewal of the investment management agreement. Management Fee and Expenses The Trustees considered information showing the fees and expenses of the Fund in comparison to the management fees of its peer group of funds as classified by Morningstar and also to the expense ratios of a peer group of funds selected on the basis of criteria determined by the Independent Trustees for this purpose using data provided by Strategic Insight Mutual Fund Research and Consulting, LLC (Strategic Insight), an independent third party. The peer group comparisons referred to below are organized in quintiles. Each quintile represents one-fifth of the peer group. In all peer group comparisons referred to below, first quintile is most favorable to the Fund's shareowners. The Trustees noted that they separately review and consider the impact of the Fund's transfer agency and Fund- and APAM-paid expenses for sub-transfer agency and intermediary arrangements, and that the results of the most recent such review were considered in the consideration of the Fund's expense ratio. The Trustees considered that the Fund's management fee for the most recent fiscal year was in the first quintile relative to the management fees paid by other funds in its Morningstar category for the comparable period. The Trustees noted the impact of the Fund's performance on the management fee paid by the Fund. The Trustees also considered the breakpoints in the management fee schedule and the reduced fee rates above certain asset levels. The Trustees considered that the expense ratio of the Fund's Class A shares for the most recent fiscal year was in the first quintile relative to its Strategic Insight peer group for the comparable period. The Trustees reviewed management fees charged by APAM and APIAM to institutional and other clients, including publicly offered European funds sponsored by APAM's affiliates, unaffiliated U.S. registered investment companies (in a sub-advisory capacity), and unaffiliated foreign and domestic separate accounts. The Trustees also considered APAM's costs in providing services to the Fund and APAM's and APIAM's costs in providing services to the other clients and considered the differences in management fees and profit margins for fund and non-fund services. In evaluating the fees associated with APAM's and APIAM's client accounts, the Trustees took into account the respective demands, resources and complexity associated with the Fund and other client accounts. The Trustees noted that, in some instances, the fee rates Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 47 for those clients were lower than the management fee for the Fund and considered that, under the investment management agreement with the Fund, APAM performs additional services for the Fund that it does not provide to those other clients or services that are broader in scope, including oversight of the Fund's other service providers and activities related to compliance and the extensive regulatory and tax regimes to which the Fund is subject. The Trustees also considered the entrepreneurial risks associated with APAM's management of the Fund. The Trustees concluded that the management fee payable by the Fund to APAM was reasonable in relation to the nature and quality of the services provided by APAM. Profitability The Trustees considered information provided by APAM regarding the profitability of APAM with respect to the advisory services provided by APAM to the Fund, including the methodology used by APAM in allocating certain of its costs to the management of the Fund. The Trustees also considered APAM's profit margin in connection with the overall operation of the Fund. They further reviewed the financial results, including the profit margins, realized by APAM and APIAM from non-fund businesses. The Trustees considered APAM's profit margins in comparison to the limited industry data available and noted that the profitability of any adviser was affected by numerous factors, including its organizational structure and method for allocating expenses. The Trustees concluded that APAM's profitability with respect to the management of the Fund was not unreasonable. Economies of Scale The Trustees considered APAM's views relating to economies of scale in connection with the Pioneer Funds as fund assets grow and the extent to which any such economies of scale are shared with the Fund and Fund shareholders. The Trustees noted the breakpoints in the management fee schedule. The Trustees recognize that economies of scale are difficult to identify and quantify, and that, among other factors that may be relevant, are the following: fee levels, expense subsidization, investment by APAM in research and analytical capabilities and APAM's commitment and resource allocation to the Fund. The Trustees noted that profitability also may be an indicator of the availability of any economies of scale, although profitability may vary for other reasons including due to reductions in expenses. The Trustees concluded that economies of scale, if any, were being appropriately shared with the Fund. 48 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 Other Benefits The Trustees considered the other benefits that APAM enjoys from its relationship with the Fund. The Trustees considered the character and amount of fees paid or to be paid by the Fund, other than under the investment management agreement, for services provided by APAM and its affiliates. The Trustees further considered the revenues and profitability of APAM's businesses other than the Fund business. To the extent applicable, the Trustees also considered the benefits to the Fund and to APAM and its affiliates from the use of "soft" commission dollars generated by the Fund to pay for research and brokerage services. The Trustees considered that Amundi Pioneer is the principal U.S. asset management business of Amundi, which is one of the largest asset managers globally. Amundi's worldwide asset management business manages over $1.7 trillion in assets (including the Pioneer Funds). The Trustees considered that APAM's relationship with Amundi creates potential opportunities for APAM, APIAM and Amundi that derive from APAM's relationships with the Fund, including Amundi's ability to market the services of APAM globally. The Trustees noted that APAM has access to additional research and portfolio management capabilities as a result of its relationship with Amundi and Amundi's enhanced global presence that may contribute to an increase in the resources available to APAM. The Trustees considered that APAM and the Fund receive reciprocal intangible benefits from the relationship, including mutual brand recognition and, for the Fund, direct and indirect access to the resources of a large global asset manager. The Trustees concluded that any such benefits received by APAM as a result of its relationship with the Fund were reasonable. Conclusion After consideration of the factors described above as well as other factors, the Trustees, including the Independent Trustees, concluded that the investment management agreement for the Fund, including the fees payable thereunder, was fair and reasonable and voted to approve the proposed renewal of the investment management agreement. Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 49 Trustees, Officers and Service Providers Investment Adviser Amundi Pioneer Asset Management, Inc. Custodian and Sub-Administrator Brown Brothers Harriman & Co. Independent Registered Public Accounting Firm Ernst & Young LLP Principal Underwriter Amundi Pioneer Distributor, Inc. Legal Counsel Morgan, Lewis & Bockius LLP Shareowner Services and 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. This information is also available on the Securities and Exchange Commission's web site at www.sec.gov. Trustees and Officers The Fund's Trustees and officers are listed below, together with their principal occupations and other directorships they have held during at least the past five years. Trustees who are interested persons of the Fund within the meaning of the 1940 Act are referred to as Interested Trustees. Trustees who are not interested persons of the Fund are referred to as Independent Trustees. Each of the Trustees serves as a Trustee of each of the 43 U.S. registered investment portfolios for which Amundi Pioneer serves as investment adviser (the "Pioneer Funds"). The address for all Trustees and all officers of the Fund is 60 State Street, Boston, Massachusetts 02109. The Statement of Additional Information of the Fund includes additional information about the Trustees and is available, without charge, upon request, by calling 1-800-225-6292. 50 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 Independent Trustees ------------------------------------------------------------------------------------------------------------------------------------ Name, Age and Position Term of Office and Other Directorships Held With the Fund Length of Service Principal Occupation Held by Trustee ------------------------------------------------------------------------------------------------------------------------------------ Thomas J. Perna (68) Trustee since 2006. Private investor (2004 - 2008 and 2013 - Director, Broadridge Financial Chairman of the Serves until a present); Chairman (2008 - 2013) and Chief Solutions, Inc. (investor Board and Trustee successor trustee is Executive Officer (2008 - 2012), Quadriserv, communications and securities elected or earlier Inc. (technology products for securities lending processing provider for retirement or industry); and Senior Executive Vice President, financial services industry) removal. The Bank of New York (financial and securities (2009 - present); Director, services) (1986 - 2004) Quadriserv, Inc. (2005 - 2013); and Commissioner, New Jersey State Civil Service Commission (2011 - 2015) ------------------------------------------------------------------------------------------------------------------------------------ David R. Bock (74) Trustee since 2005. Managing Partner, Federal City Capital Advisors Director of New York Mortgage Trustee Serves until a (corporate advisory services company) (1997 - Trust(publicly-traded mortgage successor trustee is 2004 and 2008 - present); Interim Chief REIT) (2004 - 2009, 2012 - elected or earlier Executive Officer, Oxford Analytica, Inc. present); Director of The Swiss retirement or (privately held research and consulting company) Helvetia Fund, Inc. (closed- removal. (2010); Executive Vice President and Chief end fund) (2010 - 2017); Financial Officer, I-trax, Inc. (publicly traded Director of Oxford Analytica, health care services company) (2004 - 2007); and Inc. (2008 - 2015); and Executive Vice President and Chief Financial Director of Enterprise Officer, Pedestal Inc. (internet-based mortgage Community Investment, Inc. trading company) (2000 - 2002); Private (privately-held affordable Consultant (1995 - 1997); Managing Director, housing finance company) (1985 Lehman Brothers (1992 - 1995); and Executive, - 2010) The World Bank (1979 - 1992) ------------------------------------------------------------------------------------------------------------------------------------ Benjamin M. Friedman (74) Trustee since 2008. William Joseph Maier Professor of Political Trustee, Mellon Institutional Trustee Serves until a Economy, Harvard University (1972 - present) Funds Investment Trust and successor trustee is Mellon Institutional Funds elected or earlier Master Portfolio (oversaw 17 retirement or portfolios in fund complex) removal. (1989 - 2008) ------------------------------------------------------------------------------------------------------------------------------------ Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 51 Independent Trustees (continued) ------------------------------------------------------------------------------------------------------------------------------------ Name, Age and Position Term of Office and Other Directorships Held With the Fund Length of Service Principal Occupation Held by Trustee ------------------------------------------------------------------------------------------------------------------------------------ Margaret B.W. Graham (71) Trustee since 1990. Founding Director, Vice-President and Corporate None Trustee Serves until a Secretary, The Winthrop Group, Inc. (consulting successor trustee is firm) (1982 - present); Desautels Faculty of elected or earlier Management, McGill University (1999 - 2017); and retirement or Manager of Research Operations and removal. Organizational Learning, Xerox PARC, Xerox's advance research center (1990-1994) ------------------------------------------------------------------------------------------------------------------------------------ Lorraine H. Monchak (62) Trustee since 2017. Chief Investment Officer, 1199 SEIU Funds None Trustee (Advisory Trustee (healthcare workers union pension funds) (2001 - from 2014 - 2017) present); Vice President - International Serves until a Investments Group, American International Group, successor trustee is Inc. (insurance company) (1993 - 2001); Vice elected or earlier President - Corporate Finance and Treasury retirement or Group, Citibank, N.A. (1980 - 1986 and 1990 - removal. 1993); Vice President - Asset/Liability Management Group, Federal Farm Funding Corporation (government-sponsored issuer of debt securities) (1988 - 1990); Mortgage Strategies Group, Shearson Lehman Hutton, Inc. (investment bank) (1987 - 1988); and Mortgage Strategies Group, Drexel Burnham Lambert, Ltd. (investment bank) (1986 - 1987) ------------------------------------------------------------------------------------------------------------------------------------ Marguerite A. Piret (70) Trustee since 1990. President and Chief Executive Officer, Newbury Director of New America High Trustee Serves until a Piret Company (investment banking firm) (1981 - Income Fund, Inc. (closed-end successor trustee is present) investment company) (2004 - elected or earlier present); and Member, Board of retirement or Governors, Investment Company removal. Institute (2000 - 2006) ------------------------------------------------------------------------------------------------------------------------------------ Fred J. Ricciardi (71) Trustee since 2014. Consultant (investment company services) (2012 - None Trustee Serves until a present); Executive Vice President, BNY Mellon successor trustee is (financial and investment company services) elected or earlier (1969 - 2012); Director, BNY International retirement or Financing Corp. (financial services) (2002 - removal. 2012); and Director, Mellon Overseas Investment Corp. (financial services) (2009 - 2012) ------------------------------------------------------------------------------------------------------------------------------------ 52 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 Interested Trustees ------------------------------------------------------------------------------------------------------------------------------------ Name, Age and Position Term of Office and Other Directorships Held With the Fund Length of Service Principal Occupation Held by Trustee ------------------------------------------------------------------------------------------------------------------------------------ Lisa M. Jones (56)* Trustee since 2017. Director, CEO and President of Amundi Pioneer None Trustee, President and Serves until a Asset Management USA, Inc. (since September Chief Executive Officer successor trustee is 2014); Director, CEO and President of Amundi elected or earlier Pioneer Asset Management, Inc. (since September retirement or 2014); Director, CEO and President of Amundi removal Pioneer Distributor, Inc. (since September 2014); Director, CEO and President of Amundi Pioneer Institutional Asset Management, Inc. (since September 2014); Chair, Amundi Pioneer Asset Management USA, Inc., Amundi Pioneer Distributor, Inc. and Amundi Pioneer Institutional Asset Management, Inc. (September 2014 - 2018); Managing Director, Morgan Stanley Investment Management (2010 - 2013); and Director of Institutional Business, CEO of International, Eaton Vance Management (2005 - 2010) ------------------------------------------------------------------------------------------------------------------------------------ Kenneth J. Taubes (60)* Trustee since 2014. Director and Executive Vice President (since None Trustee Serves until a 2008) and Chief Investment Officer, U.S. (since successor trustee is 2010) of Amundi Pioneer Asset Management USA, elected or earlier Inc.; Executive Vice President and Chief retirement or Investment Officer, U.S. of Amundi Pioneer removal (since 2008); Executive Vice President of Amundi Pioneer Institutional Asset Management, Inc. (since 2009); and Portfolio Manager of Amundi Pioneer (since 1999) ------------------------------------------------------------------------------------------------------------------------------------ * Ms. Jones and Mr. Taubes are Interested Trustees because they are officers or directors of the Fund's investment adviser and certain of its affiliates. Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 53 Fund Officers ------------------------------------------------------------------------------------------------------------------------------------ Name, Age and Position Term of Office and Other Directorships Held With the Fund Length of Service Principal Occupation Held by Officer ------------------------------------------------------------------------------------------------------------------------------------ Christopher J. Kelley (53) Since 2003. Serves Vice President and Associate General Counsel of None Secretary and at the discretion of Amundi Pioneer since January 2008; Secretary and Chief Legal Officer the Board Chief Legal Officer of all of the Pioneer Funds since June 2010; Assistant Secretary of all of the Pioneer Funds from September 2003 to May 2010; and Vice President and Senior Counsel of Amundi Pioneer from July 2002 to December 2007 ------------------------------------------------------------------------------------------------------------------------------------ Carol B. Hannigan (57) Since 2010. Serves Fund Governance Director of Amundi Pioneer since None Assistant Secretary at the discretion of December 2006 and Assistant Secretary of all the the Board Pioneer Funds since June 2010; Manager - Fund Governance of Amundi Pioneer from December 2003 to November 2006; and Senior Paralegal of Amundi Pioneer from January 2000 to November 2003 ------------------------------------------------------------------------------------------------------------------------------------ Thomas Reyes (55) Since 2010. Serves Senior Counsel of Amundi Pioneer since May 2013 None Assistant Secretary at the discretion of and Assistant Secretary of all the Pioneer Funds the Board since June 2010; and Counsel of Amundi Pioneer from June 2007 to May 2013 ------------------------------------------------------------------------------------------------------------------------------------ Mark E. Bradley (58) Since 2008. Serves Vice President - Fund Treasury of Amundi None Treasurer and at the discretion of Pioneer; Treasurer of all of the Pioneer Funds Chief Financial and the Board since March 2008; Deputy Treasurer of Amundi Accounting Officer Pioneer from March 2004 to February 2008; and Assistant Treasurer of all of the Pioneer Funds from March 2004 to February 2008 ------------------------------------------------------------------------------------------------------------------------------------ Luis I. Presutti (53) Since 2000. Serves Director - Fund Treasury of Amundi Pioneer; and None Assistant Treasurer at the discretion of Assistant Treasurer of all of the Pioneer Funds the Board ------------------------------------------------------------------------------------------------------------------------------------ Gary Sullivan (60) Since 2002. Serves Senior Manager - Fund Treasury of Amundi None Assistant Treasurer at the discretion of Pioneer; and Assistant Treasurer of all of the the Board Pioneer Funds ------------------------------------------------------------------------------------------------------------------------------------ 54 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 ------------------------------------------------------------------------------------------------------------------------------------ Name, Age and Position Term of Office and Other Directorships Held With the Fund Length of Service Principal Occupation Held by Officer ------------------------------------------------------------------------------------------------------------------------------------ David F. Johnson (38) Since 2009. Serves Senior Manager - Fund Treasury of Amundi Pioneer None Assistant Treasurer at the discretion of since November 2008; Assistant Treasurer of all the Board of the Pioneer Funds since January 2009; and Client Service Manager - Institutional Investor Services at State Street Bank from March 2003 to March 2007 ------------------------------------------------------------------------------------------------------------------------------------ John Malone (47) Since 2018. Serves Managing Director, Chief Compliance Officer of None Chief Compliance Officer at the discretion of Amundi Pioneer Asset Management; Amundi Pioneer the Board Institutional Asset Management, Inc.; and the Pioneer Funds since September 2018; and Chief Compliance Officer of Amundi Pioneer Distributor, Inc. since January 2014. ------------------------------------------------------------------------------------------------------------------------------------ Kelly O'Donnell (47) Since 2006. Serves Vice President - Investor Services Group of None Anti-Money Laundering at the discretion of Amundi Pioneer and Anti-Money Laundering Officer Officer the Board of all the Pioneer Funds since 2006 ------------------------------------------------------------------------------------------------------------------------------------ Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 55 This page is for your notes. 56 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 This page is for your notes. Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 57 This page is for your notes. 58 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 This page is for your notes. Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 59 This page is for your notes. 60 Pioneer Mid Cap Value Fund | Annual Report | 10/31/18 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 55014 Boston, Massachusetts 02205-5014 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 This report must be preceded or accompanied by a prospectus. The Fund files a complete schedule of investments with the Securities and Exchange Commission for the first and third quarters for each fiscal year on Form N-Q. Shareholders may view the filed Form N-Q by visiting the Commission's web site at www.sec.gov. [LOGO] Amundi Pioneer ============== ASSET MANAGEMENT Amundi Pioneer Asset Management, Inc. 60 State Street Boston, MA 02109 www.amundipioneer.com Securities offered through Amundi Pioneer Distributor, Inc. 60 State Street, Boston, MA 02109 Underwriter of Pioneer Mutual Funds, Member SIPC [C] 2018 Amundi Pioneer Asset Management 19443-12-1218 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)). Ms. Marguerite A. Piret, 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. The audit fees for the Fund were $23,000 payable to Ernst & Young LLP for the year ended October 31, 2018 and $23,000 payable for the year ended October 31, 2017. (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. There were no audit-related services in 2018 or 2017. (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. The tax fees for the Fund were $8,028 payable to Ernst & Young LLP for the year ended October 31, 2018 and $8,028 for the year ended October 31, 2017. (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. There were no other fees in 2018 or 2017. (e) (1) Disclose the audit committee's pre-approval policies and procedures described in paragraph (c)(7) of Rule 2-01 of Regulation S-X. PIONEER FUNDS APPROVAL OF AUDIT, AUDIT-RELATED, TAX AND OTHER SERVICES PROVIDED BY THE INDEPENDENT AUDITOR SECTION I - POLICY PURPOSE AND APPLICABILITY The Pioneer Funds recognize the importance of maintaining the independence of their outside auditors. Maintaining independence is a shared responsibility involving Amudi Pioneer Asset Management, Inc, the audit committee and the independent auditors. The Funds recognize that a Fund's independent auditors: 1) possess knowledge of the Funds, 2) are able to incorporate certain services into the scope of the audit, thereby avoiding redundant work, cost and disruption of Fund personnel and processes, and 3) have expertise that has value to the Funds. As a result, there are situations where it is desirable to use the Fund's independent auditors for services in addition to the annual audit and where the potential for conflicts of interests are minimal. Consequently, this policy, which is intended to comply with Rule 210.2-01(C)(7), sets forth guidelines and procedures to be followed by the Funds when retaining the independent audit firm to perform audit, audit-related tax and other services under those circumstances, while also maintaining independence. Approval of a service in accordance with this policy for a Fund shall also constitute approval for any other Fund whose pre-approval is required pursuant to Rule 210.2-01(c)(7)(ii). In addition to the procedures set forth in this policy, any non-audit services that may be provided consistently with Rule 210.2-01 may be approved by the Audit Committee itself and any pre-approval that may be waived in accordance with Rule 210.2-01(c)(7)(i)(C) is hereby waived. Selection of a Fund's independent auditors and their compensation shall be determined by the Audit Committee and shall not be subject to this policy. SECTION II - POLICY ---------------- -------------------------------- ------------------------------------------------- SERVICE SERVICE CATEGORY DESCRIPTION SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES CATEGORY ---------------- -------------------------------- ------------------------------------------------- I. AUDIT Services that are directly o Accounting research assistance SERVICES related to performing the o SEC consultation, registration independent audit of the Funds statements, and reporting o Tax accrual related matters o Implementation of new accounting standards o Compliance letters (e.g. rating agency letters) o Regulatory reviews and assistance regarding financial matters o Semi-annual reviews (if requested) o Comfort letters for closed end offerings ---------------- -------------------------------- ------------------------------------------------- II. Services which are not o AICPA attest and agreed-upon procedures AUDIT-RELATED prohibited under Rule o Technology control assessments SERVICES 210.2-01(C)(4) (the "Rule") o Financial reporting control assessments and are related extensions of o Enterprise security architecture the audit services support the assessment audit, or use the knowledge/expertise gained from the audit procedures as a foundation to complete the project. In most cases, if the Audit-Related Services are not performed by the Audit firm, the scope of the Audit Services would likely increase. The Services are typically well-defined and governed by accounting professional standards (AICPA, SEC, etc.) ---------------- -------------------------------- ------------------------------------------------- ------------------------------------- ------------------------------------ AUDIT COMMITTEE APPROVAL POLICY AUDIT COMMITTEE REPORTING POLICY ------------------------------------- ------------------------------------ o "One-time" pre-approval o A summary of all such for the audit period for all services and related fees pre-approved specific service reported at each regularly subcategories. Approval of the scheduled Audit Committee independent auditors as meeting. auditors for a Fund shall constitute pre approval for these services. ------------------------------------- ------------------------------------ o "One-time" pre-approval o A summary of all such for the fund fiscal year within services and related fees a specified dollar limit (including comparison to for all pre-approved specified dollar limits) specific service subcategories reported quarterly. o Specific approval is needed to exceed the pre-approved dollar limit for these services (see general Audit Committee approval policy below for details on obtaining specific approvals) o Specific approval is needed to use the Fund's auditors for Audit-Related Services not denoted as "pre-approved", or to add a specific service subcategory as "pre-approved" ------------------------------------- ------------------------------------ SECTION III - POLICY DETAIL, CONTINUED ----------------------- --------------------------- ----------------------------------------------- SERVICE CATEGORY SERVICE CATEGORY SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES DESCRIPTION ----------------------- --------------------------- ----------------------------------------------- III. TAX SERVICES Services which are not o Tax planning and support prohibited by the Rule, o Tax controversy assistance if an officer of the Fund o Tax compliance, tax returns, excise determines that using the tax returns and support Fund's auditor to provide o Tax opinions these services creates significant synergy in the form of efficiency, minimized disruption, or the ability to maintain a desired level of confidentiality. ----------------------- --------------------------- ----------------------------------------------- ------------------------------------- ------------------------- AUDIT COMMITTEE APPROVAL POLICY AUDIT COMMITTEE REPORTING POLICY ------------------------------------- ------------------------- ------------------------------------- ------------------------- o "One-time" pre-approval o A summary of for the fund fiscal year all such services and within a specified dollar limit related fees 				 (including comparison 			 to specified dollar 			 limits) reported 			 quarterly. o Specific approval is needed to exceed the pre-approved dollar limits for these services (see general Audit Committee approval policy below for details on obtaining specific approvals) o Specific approval is needed to use the Fund's auditors for tax services not denoted as pre-approved, or to add a specific service subcategory as "pre-approved" ------------------------------------- ------------------------- SECTION III - POLICY DETAIL, CONTINUED ----------------------- --------------------------- ----------------------------------------------- SERVICE CATEGORY SERVICE CATEGORY SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES DESCRIPTION ----------------------- --------------------------- ----------------------------------------------- IV. OTHER SERVICES Services which are not o Business Risk Management support prohibited by the Rule, o Other control and regulatory A. SYNERGISTIC, if an officer of the Fund compliance projects UNIQUE QUALIFICATIONS determines that using the Fund's auditor to provide these services creates significant synergy in the form of efficiency, minimized disruption, the ability to maintain a desired level of confidentiality, or where the Fund's auditors posses unique or superior qualifications to provide these services, resulting in superior value and results for the Fund. ----------------------- --------------------------- ----------------------------------------------- --------------------------------------- ------------------------ AUDIT COMMITTEE APPROVAL POLICY AUDIT COMMITTEE REPORTING POLICY ------------------------------------- -------------------------- o "One-time" pre-approval o A summary of for the fund fiscal year within all such services and a specified dollar limit related fees 			 (including comparison 			 to specified dollar 				 limits) reported quarterly. o Specific approval is needed to exceed the pre-approved dollar limits for these services (see general Audit Committee approval policy below for details on obtaining specific approvals) o Specific approval is needed to use the Fund's auditors for "Synergistic" or "Unique Qualifications" Other Services not denoted as pre-approved to the left, or to add a specific service subcategory as "pre-approved" ------------------------------------- -------------------------- SECTION III - POLICY DETAIL, CONTINUED ----------------------- ------------------------- ----------------------------------------------- SERVICE CATEGORY SERVICE CATEGORY SPECIFIC PROHIBITED SERVICE SUBCATEGORIES DESCRIPTION ----------------------- ------------------------- ----------------------------------------------- PROHIBITED SERVICES Services which result 1. Bookkeeping or other services in the auditors losing related to the accounting records or independence status financial statements of the audit under the Rule. client* 2. Financial information systems design and implementation* 3. Appraisal or valuation services, fairness* opinions, or contribution-in-kind reports 4. Actuarial services (i.e., setting actuarial reserves versus actuarial audit work)* 5. Internal audit outsourcing services* 6. Management functions or human resources 7. Broker or dealer, investment advisor, or investment banking services 8. Legal services and expert services unrelated to the audit 9. Any other service that the Public Company Accounting Oversight Board determines, by regulation, is impermissible ----------------------- ------------------------- ----------------------------------------------- ------------------------------------------- ------------------------------ AUDIT COMMITTEE APPROVAL POLICY AUDIT COMMITTEE REPORTING POLICY ------------------------------------------- ------------------------------ o These services are not to be o A summary of all performed with the exception of the(*) services and related services that may be permitted fees reported at each if they would not be subject to audit regularly scheduled procedures at the audit client (as Audit Committee meeting defined in rule 2-01(f)(4)) level will serve as continual the firm providing the service. confirmation that has 				 not provided any restricted services. ------------------------------------------- ------------------------------ -------------------------------------------------------------------------------- GENERAL AUDIT COMMITTEE APPROVAL POLICY: o For all projects, the officers of the Funds and the Fund's auditors will each make an assessment to determine that any proposed projects will not impair independence. o Potential services will be classified into the four non-restricted service categories and the "Approval of Audit, Audit-Related, Tax and Other Services" Policy above will be applied. Any services outside the specific pre-approved service subcategories set forth above must be specifically approved by the Audit Committee. o At least quarterly, the Audit Committee shall review a report summarizing the services by service category, including fees, provided by the Audit firm as set forth in the above policy. -------------------------------------------------------------------------------- (2) Disclose the percentage of services described in each of paragraphs (b) through (d) of this Item that were approved by the audit committee pursuant to paragraph (c)(7)(i)(C) of Rule 2-01 of Regulation S-X. Non-Audit Services Beginning with non-audit service contracts entered into on or after May 6, 2003, the effective date of the new SEC pre-approval rules, the Fund's audit committee is required to pre-approve services to affiliates defined by SEC rules to the extent that the services are determined to have a direct impact on the operations or financial reporting of the Fund. For the years ended October 31 2018 and 2017, there were no services provided to an affiliate that required the Fund's audit committee pre-approval. (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. The aggregate non-audit fees for the Fund were $8,028 payable to Ernst & Young LLP for the year ended October 31, 2018 and $8,028 for the year ended October 31, 2017. (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 December 28, 2018 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 December 28, 2018 By (Signature and Title)* /s/ Mark E. Bradley Mark E. Bradley, Treasurer & Chief Accounting & Financial Officer Date December 28, 2018 * Print the name and title of each signing officer under his or her signature.