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



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                        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.