UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                   FORM N-CSR

                   CERTIFIED SHAREHOLDER REPORT OF REGISTERED
                        MANAGEMENT INVESTMENT COMPANIES



		Investment Company Act file number 811-01835

                          Pioneer Series Trust XI
               (Exact name of registrant as specified in charter)


                       60 State Street, Boston, MA 02109
              (Address of principal executive offices) (ZIP code)


            Terrence J. Cullen, Amundi Pioneer Asset Management, Inc.,
                       60 State Street, Boston, MA 02109
                    (Name and address of agent for service)


Registrant's telephone number, including area code:  (617) 742-7825


Date of fiscal year end:  December 31


Date of reporting period:  January 1, 2018 through December 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 Core
                                  Equity Fund

--------------------------------------------------------------------------------
                                  Annual Report | December 31, 2018
--------------------------------------------------------------------------------

                                  Ticker Symbols:

                                  Class A   PIOTX
                                  Class C   PCOTX
                                  Class K   PCEKX
                                  Class R   CERPX
                                  Class Y   PVFYX

Beginning in February 2021, as permitted by regulations adopted by the
Securities and Exchange Commission, paper copies of the Fund's shareholder
reports like this one will no longer be sent by mail, unless you specifically
request paper copies of the reports from the Fund or from your financial
intermediary, such as a broker-dealer, bank or insurance company. Instead, the
reports will be made available on the Fund's website, and you will be notified
by mail each time a report is posted and provided with a website link to access
the report.

If you already elected to receive shareholder reports electronically, you will
not be affected by this change and you need not take any action. You may elect
to receive shareholder reports and other communications electronically by
contacting your financial intermediary or, if you invest directly with the
Fund, by calling 1-800-225-6292.

You may elect to receive all future reports in paper free of charge. If you
invest directly with the Fund, you can inform the Fund that you wish to
continue receiving paper copies of your shareholder reports by calling
1-800-225-6292. If you invest through a financial intermediary, you can contact
your financial intermediary to request that you continue to receive paper
copies of your shareholder reports. Your election to receive reports in paper
will apply to all funds held in your account if you invest through your
financial intermediary or all funds held with the Pioneer funds complex if you
invest directly.

                       [LOGO]   Amundi Pioneer
                                ==============
                              ASSET MANAGEMENT


                        visit us: www.amundipioneer.com



Table of Contents



                                                                          
President's Letter                                                            2

Portfolio Management Discussion                                               4

Portfolio Summary                                                            10

Prices and Distributions                                                     11

Performance Update                                                           12

Comparing Ongoing Fund Expenses                                              17

Schedule of Investments                                                      19

Financial Statements                                                         25

Notes to Financial Statements                                                34

Report of Independent Registered Public Accounting Firm                      44

Additional Information                                                       46

Approval of Investment Management Agreement                                  48

Trustees, Officers and Service Providers                                     53


                           Pioneer Core Equity Fund | Annual Report | 12/31/18 1



President's Letter

Since 1928, active portfolio management based on in-depth, fundamental
research, has been the foundation of Amundi Pioneer's investment approach. We
believe an active management investment strategy is a prudent approach to
investing, especially during periods of market volatility, which can result
from any number of risk factors, including slow U.S. economic growth, rising
interest rates, and geopolitical factors. Of course, in today's global economy,
risk factors extend well beyond U.S. borders, and political and economic issues
on the international front can also cause or contribute to volatility in U.S.
markets.

At Amundi Pioneer, each security under consideration is researched by our team
of experienced investment professionals, who visit companies and meet with
their management teams. At the end of this research process, if we have
conviction in a company's business model and management team, and regard the
security as a potentially solid investment opportunity, an Amundi Pioneer
portfolio manager makes an active decision to invest in that security. The
portfolio resulting from these decisions represents an expression of his or her
convictions, and strives to balance overall risk and return opportunity. As an
example, the Standard & Poor's 500 Index -- the predominant benchmark for many
U.S. Large-Cap Core Equity funds -- has 500 stocks. An Amundi Pioneer portfolio
manager chooses to invest in only those companies that he or she believes can
offer the most attractive opportunities to pursue the fund's investment
objective, thus potentially benefiting the fund's shareowners. This process
results in a portfolio that does not own all 500 stocks, but a much narrower
universe. The same active decision to invest in a company is also applied when
we decide to sell a security, either due to changing fundamentals, valuation
concerns, or market risks. We apply this active decision-making across all of
our equity, fixed-income, and global portfolios.

Today, as investors, we have many options. It is our view that active
management can serve shareholders well not only when markets are thriving, but
also during periods of market volatility and uncertainty, thus making it a
compelling investment choice. As you consider the many choices today, we
encourage you to work with your financial advisor to develop an overall
investment plan that addresses both your short- and long-term goals, and to
implement such a plan in a disciplined manner.

2 Pioneer Core Equity Fund | Annual Report | 12/31/18



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.
December 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 Core Equity Fund | Annual Report | 12/31/18 3



Portfolio Management Discussion | 12/31/18

In the following interview, Craig D. Sterling discusses the market environment
and the factors that influenced the performance of Pioneer Core Equity Fund
during the 12-month period ended December 31, 2018. Mr. Sterling, Managing
Director, Director of Core Equity and Head of Equity Research, U.S., and a
portfolio manager at Amundi Pioneer Asset Management, Inc. ("Amundi Pioneer"),
is responsible for the day-to-day management of the Fund's investment
portfolio, along with Ashesh "Ace" Savla, Team Leader of U.S. Equity
Quantitative Research, a vice president, and a portfolio manager at Amundi
Pioneer.

Q     How did the Fund perform during the 12-month period ended December 31,
      2018?

A     Pioneer Core Equity Fund's Class A shares returned -8.70% at net asset
      value during the 12-month period ended December 31, 2018, while the Fund's
      benchmark, the Standard & Poor's 500 Index (the S&P 500), returned -4.38%.
      During the same period, the average return of the 1,402 mutual funds in
      Morningstar's Large Blend Funds category was -6.27%.

      We are disappointed with the Fund's performance in 2018, but we remain
      committed to our structured, disciplined investment process and emphasis
      on valuations. While short-term developments can overwhelm equity
      valuations in the short term, as we witnessed in the latter part of 2018,
      we are confident our investment process can produce competitive long-term
      results.

Q     How would you describe the environment for the U.S. stock market during
      the 12-month period ended December 31, 2018?

A     The negative return of the S&P 500 for the 12-month period belies the fact
      that the investment backdrop was in fact quite favorable for much of the
      Fund's fiscal year. From the beginning of January through late September,
      stocks were well supported by the combination of robust economic growth,
      better-than-expected corporate earnings, and investors' hearty appetite
      for risk. Although that portion of the year brought its share of market
      volatility and adverse headlines, the S&P 500 nonetheless touched a record
      high in late September.

4 Pioneer Core Equity Fund | Annual Report | 12/31/18



      September proved to be the high-water mark for the S&P 500, however, as
      stocks subsequently experienced a sharp sell-off that erased all of the
      earlier gains and caused the S&P 500 to fall into negative territory for
      the year. A wide variety of factors contributed to the downturn, including
      a slowdown in global economic growth, uncertainty surrounding U.S. trade
      policy, and falling corporate earnings estimates for 2019. Stocks were
      further pressured by the U.S. Federal Reserve's (the Fed's) poorly
      communicated monetary policy outlook and, in December, the prospect of a
      U.S. government shutdown.

Q     What were the most important factors driving the Fund's benchmark-relative
      performance during the 12-month period ended December 31, 2018?

A     Three aspects of the Fund's positioning affected its benchmark-relative
      results in 2018. First, the portfolio entered the latter part of the year
      with a tilt toward the economically sensitive areas of the market, through
      overweights in the industrials and financials sectors. As a result, the
      Fund experienced an outsized negative performance impact once concerns
      about economic growth caused those sectors to slump during the sell-off in
      the fourth quarter. Among the individual portfolio positions that notably
      detracted from the Fund's benchmark-relative returns in those sectors were
      Bank of America, in financials, and United Rentals, Masco, and FedEx, in
      industrials.

      Despite their recent struggles, we believe many companies in those sectors
      are better managed than they were during past cycles, with more stable
      business models that are less sensitive to cyclical peaks and troughs. Our
      long-term view is that those traits will ultimately be reflected in their
      stock prices; however, it became clear by the end of the year that the
      market wants to see those companies manage through a downturn, or a period
      of stress, before awarding them higher valuations. Still, banks today
      feature more stable profits, lower levels of leverage, a greater focus on
      shareholder returns through buybacks and dividends*, and less regulatory
      pressure than they have faced historically.

      We also see long-term opportunities in non-residential construction
      companies and those that can capitalize on positive trends in home repair
      and remodeling. We believe such companies can benefit from the demographic
      tailwinds currently supporting household formation, as well as the
      continued strength in U.S. economic growth.

*     Dividends are not guaranteed.

                           Pioneer Core Equity Fund | Annual Report | 12/31/18 5



      Second, the portfolio was less defensive than the market as a whole due to
      underweight positions in the utilities and health care sectors, which
      detracted from the Fund's benchmark-relative performance. Believing
      utilities' valuations were excessive, we could not justify holding a
      meaningful position in the portfolio. In health care, we maintained an
      underweight relative to the S&P 500 in pharmaceuticals & biotechnology
      stocks, given our view that an adverse pricing environment and rising
      competition would represent important challenges. The pharma/biotech area
      had lagged in recent years, but it strongly outperformed in the latter
      half of 2018, and so the Fund's underweight hurt benchmark-relative
      returns.

      The third key aspect of the Fund's broader positioning, which was our
      decision to underweight the portfolio to mega-cap, high-momentum
      technology stocks, had a positive effect on benchmark-relative performance
      during the 12-month period. Although we were early in making that shift
      within the portfolio, the Fund's underweight contributed positively to
      relative returns once the information technology sector's performance
      turned lower in the fourth quarter. We also added value by maintaining a
      Fund position in Microsoft, whose robust fundamentals enabled it to
      outperform during both the market rally and the subsequent downturn.

Q     What were some other notable aspects of the portfolio's positioning that
      affected the Fund's benchmark-relative results during the 12-month period
      ended December 31, 2018?

A     The energy sector also proved to be a challenging area for the Fund during
      the period due to overweight positions, relative to the S&P 500, in three
      equipment-and-services stocks -- Halliburton, Schlumberger, and National
      Oilwell Varco -- that all lost considerable ground when oil prices plunged
      in the fourth quarter. Oilfield-services companies are sensitive to
      expectations for capital spending by major, integrated oil producers, and
      so concerns about the health of the broader sector tended to weigh heavily
      on that segment during the period. By the end of the 12-month period,
      National Oilwell Varco was no longer a Fund holding. At the same time,
      however, we had come to believe that valuations in the industry had
      reached depressed levels, and so we decided to retain the Fund's position
      in Halliburton, which we regard as one of the best oilfield-services firms
      in the field.

      On the plus side, the Fund's holdings in consumer staples posted a gain in
      aggregate and also outpaced the overall sector by a wide margin, thus
      benefiting benchmark-relative performance. The Fund entered 2018 with a
      very low weighting in the sector, which reflected our view that many

6 Pioneer Core Equity Fund | Annual Report | 12/31/18



      companies in the food/beverage/tobacco and household/personal care
      products industries were too richly valued, especially given the
      challenges from rising online competition and increasing price
      transparency. The consumer staples sector indeed underperformed in the
      first half of 2018, and so the Fund's underweight was a plus. In the
      second half of the year, we sought to take advantage of the improved
      valuations created by the first-half weakness in the sector by
      establishing overweight positions in Procter & Gamble (P&G) and PepsiCo,
      both of which are components of the S&P 500. By the end of the period, the
      overweights in those two stocks had benefited the Fund's
      benchmark-relative performance, with P&G actually finishing the 12-month
      period as the top overall positive contributor to relative returns.

      The Fund's investments in two restaurant operators that performed well due
      to the continued strength in consumer spending -- Yum! Brands and Chipotle
      Mexican Grill -- also made sizable positive contributions to
      benchmark-relative returns during the period.

Q     Did the Fund own any derivative securities during the 12-month period
      ended December 31, 2018? If so, did the investments have a material impact
      on benchmark-relative results?

A     At certain points in the year, we owned S&P 500 futures contracts in lieu
      of cash to maintain market exposure without reducing portfolio liquidity.
      Our view that valuations had become overextended following the January
      2018 market rally prompted us to buy futures contracts to guard against a
      potential downturn. The futures market was not pricing in much volatility
      in the equity market at the time, and so we were able to purchase the
      futures at a very reasonable cost. The futures contracts benefited the
      Fund's relative performance when the market corrected in late January and
      into February 2018. We subsequently closed out the position.

Q     How would you characterize the Fund's overall positioning at the close of
      the fiscal year ended December 31, 2018?

A     Generally speaking, we have favored owning shares of three types of
      companies in the portfolio. First, we have sought to own stocks of
      companies with strong underlying businesses that we believe can continue
      to post solid results, even if the economy experiences a meaningful
      slowdown. We have been finding a number of those ideas among the mega-cap
      technology stocks that corrected in the fourth quarter of 2018, such as
      Microsoft, Amazon.com, Alphabet, Apple, and Salesforce.com.

                           Pioneer Core Equity Fund | Annual Report | 12/31/18 7



      Additionally, we favor companies with stable, defensive business models
      and attractive valuations. Such companies can potentially provide a
      measure of defensiveness to the portfolio, which may prove helpful if the
      stock market continues to experience disruptions in 2019. Prime examples
      of such companies include Progressive, a leading auto and home insurance
      firm, Marsh & McLennan, the largest commercial insurance broker, and
      IntercontinentalExchange, a leading operator of stock and commodity
      exchanges. AT&T and Raytheon also represent top portfolio holdings in that
      area. Conversely, the Fund is underweight versus the S&P 500 to
      historically defensive sectors such as consumer staples and utilities.
      While many companies in those sectors feature stable business models, we
      believe they are vulnerable to underperformance due to their excessive
      valuations.

      In addition, we have maintained Fund positions in cyclical companies that
      we think were punished too severely during the sell-off in late 2018,
      including United Rentals, Stanley Black & Decker, and Micron Technology.
      In our view, those types of companies are poised for a recovery if the
      deceleration in economic growth proves less severe than expected. The
      stocks closed the 2018 calendar year at valuations that we would expect to
      see during a severe recession, a scenario we view as highly unlikely.

8 Pioneer Core Equity Fund | Annual Report | 12/31/18



Please refer to the Schedule of Investments on pages 19-24 for a full listing
of Fund securities.

All investments are subject to risk, including the possible loss of principal.
In the past several years, financial markets have experienced increased
volatility, depressed valuations, decreased liquidity and heightened
uncertainty. These conditions may continue, recur, worsen or spread.

At times, the Fund's investments may represent industries or industry sectors
that are interrelated or have common risks, making it more susceptible to any
economic, political, or regulatory developments or other risks affecting those
industries and sectors.

Investing in foreign and/or emerging markets securities involves risks relating
to interest rates, currency exchange rates, economic, and political
conditions.

These risks may increase share price volatility.

Before investing, consider the product's investment objectives, risks, charges
and expenses. Contact your advisor or Amundi Pioneer Asset Management, Inc.,
for a prospectus or summary prospectus containing this information. Read it
carefully.

Any information in this shareholder report regarding market or economic trends
or the factors influencing the Fund's historical or future performance are
statements of opinion as of the date of this report. Past performance is no
guarantee of future results.

                           Pioneer Core Equity Fund | Annual Report | 12/31/18 9



Portfolio Summary | 12/31/18

Sector Distribution
--------------------------------------------------------------------------------
(As a percentage of total investments)*



                                                                        
Information Technology                                                     17.7%
Financials                                                                 16.6%
Health Care                                                                12.6%
Consumer Discretionary                                                     12.5%
Industrials                                                                11.1%
Communication Services                                                     11.1%
Consumer Staples                                                            7.1%
Energy                                                                      5.5%
Materials                                                                   2.7%
Utilities                                                                   1.5%
Real Estate                                                                 1.5%
Government                                                                  0.1%


10 Largest Holdings
--------------------------------------------------------------------------------
(As a percentage of total investments)*



                                                                        
 1. Microsoft Corp.                                                        4.96%
--------------------------------------------------------------------------------
 2. Apple, Inc.                                                            4.44
--------------------------------------------------------------------------------
 3. AT&T, Inc.                                                             4.22
--------------------------------------------------------------------------------
 4. Alphabet, Inc.                                                         4.14
--------------------------------------------------------------------------------
 5. Amazon.com, Inc.                                                       3.92
--------------------------------------------------------------------------------
 6. Intercontinental Exchange, Inc.                                        3.61
--------------------------------------------------------------------------------
 7. Raytheon Co.                                                           3.45
--------------------------------------------------------------------------------
 8. PepsiCo., Inc.                                                         3.24
--------------------------------------------------------------------------------
 9. TOTAL SA (A.D.R.)                                                      2.96
--------------------------------------------------------------------------------
10. Marsh & McLennan Cos., Inc.                                            2.55
--------------------------------------------------------------------------------


*     Excludes temporary cash investments and all derivative contracts except
      for options purchased. The Fund is actively managed, and current holdings
      may be different. The holdings listed should not be considered
      recommendations to buy or sell any securities.

10 Pioneer Core Equity Fund | Annual Report | 12/31/18



Prices and Distributions | 12/31/18

Net Asset Value per Share
--------------------------------------------------------------------------------



--------------------------------------------------------------------------------
          Class             12/31/18                  12/31/17
--------------------------------------------------------------------------------
                                                 
           A                 $15.93                    $20.58
--------------------------------------------------------------------------------
           C                 $13.82                    $18.26
--------------------------------------------------------------------------------
           Y                 $16.14                    $20.80


--------------------------------------------------------------------------------
          Class             12/31/18                   5/4/18
--------------------------------------------------------------------------------
                                                 
           K*                $15.91                    $20.82


--------------------------------------------------------------------------------
          Class             12/31/18                  6/29/18
--------------------------------------------------------------------------------
                                                 
           R**               $15.90                    $21.08
--------------------------------------------------------------------------------


Distributions per Share: 1/1/18 - 12/31/18



--------------------------------------------------------------------------------
                     Net Investment         Short-Term           Long-Term
          Class         Income            Capital Gains        Capital Gains
--------------------------------------------------------------------------------
                                                        
           A           $0.1420              $0.2174              $2.7836
--------------------------------------------------------------------------------
           C           $    --              $0.2174              $2.7836
--------------------------------------------------------------------------------
           K*          $0.2050              $0.2174              $2.7836
--------------------------------------------------------------------------------
           R**         $0.1595              $0.2174              $2.7836
--------------------------------------------------------------------------------
           Y           $0.1673              $0.2174              $2.7836
--------------------------------------------------------------------------------


Index Definition
--------------------------------------------------------------------------------
The Standard & Poor's 500 Index is an unmanaged, commonly used measure of the
broad U.S. stock market. Index returns are calculated monthly, assume
reinvestment of dividends and, unlike Fund returns, do not reflect any fees,
expenses or sales charges. It is not possible to invest directly in an index.

The index defined here pertains to the "Value of $10,000 Investment" and "Value
of $5 Million Investment" charts on pages 12-16.

*     Class K shares commenced operations on May 4, 2018.

**    Class R shares commenced operations on June 29, 2018.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 11



Performance Update | 12/31/18                                     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 Core Equity Fund at public
offering price during the periods shown, compared to that of the Standard &
Poor's 500 Index.



Average Annual Total Returns
(As of December 31, 2018)
---------------------------------------------------
                 Net         Public
                 Asset       Offering      S&P
                 Value       Price         500
Period           (NAV)       (POP)         Index
---------------------------------------------------
                                  
10 years         11.75%       11.09%       13.12%
5 years           6.08         4.83         8.49
1 year           -8.70       -13.95        -4.38
---------------------------------------------------


Expense Ratio
(Per prospectus dated June 1, 2018)
---------------------------------------------------
                Gross
---------------------------------------------------
             
                0.89%
---------------------------------------------------


[THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL]

Value of $10,000 Investment



                                    Pioneer Core
                                    Equity Fund         S&P 500 Index
                                                  
12/08                               $ 9,425             $10,000
12/09                               $12,168             $12,646
12/10                               $14,064             $14,551
12/11                               $14,201             $14,859
12/12                               $16,262             $17,237
12/13                               $21,305             $22,819
12/14                               $23,530             $25,943
12/15                               $23,180             $26,302
12/16                               $25,126             $29,448
12/17                               $31,349             $35,876
12/18                               $28,623             $34,303


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. NAV
returns would have been lower had sales charges been reflected. POP returns
reflect deduction of maximum 5.75% sales charge. All results are historical and
assume the reinvestment of dividends and capital gains. Other share classes are
available for which performance and expenses will differ.

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

The performance table and graph do not reflect the deduction of fees and taxes
that a shareowner would pay on Fund distributions or the redemption of Fund
shares.

The Fund acquired the assets and liabilities of Pioneer Research Fund ("the
predecessor fund") on June 7, 2013. As a result of the reorganization, the
predecessor fund's performance and financial history became the performance and
financial history of the Fund. The performance of Class A shares of the Fund is
the performance of Class A shares of the predecessor fund for periods prior to
the reorganization, and has not been restated to reflect any differences in
expenses.

Please refer to the financial highlights for a more current expense ratio.

12 Pioneer Core Equity Fund | Annual Report | 12/31/18


Performance Update | 12/31/18                                     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 Core Equity Fund for the periods
shown, compared to that of the Standard & Poor's 500 Index.



Average Annual Total Returns
(As of December 31, 2018)
---------------------------------------------------
                                           S&P
                 If          If            500
Period           Held        Redeemed      Index
---------------------------------------------------
                                  
10 years         10.78%      10.78%        13.12%
5 years           5.21        5.21          8.49
1 year           -9.45       -9.45         -4.38
---------------------------------------------------


Expense Ratio
(Per prospectus dated June 1, 2018)
---------------------------------------------------
                Gross
---------------------------------------------------
             
                1.71%
---------------------------------------------------


[THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL]

Value of $10,000 Investment



                                    Pioneer Core
                                    Equity Fund         S&P 500 Index
                                                  
12/08                               $10,000             $10,000
12/09                               $12,793             $12,646
12/10                               $14,651             $14,551
12/11                               $14,667             $14,859
12/12                               $16,627             $17,237
12/13                               $21,585             $22,819
12/14                               $23,640             $25,943
12/15                               $23,087             $26,302
12/16                               $24,836             $29,448
12/17                               $30,733             $35,876
12/18                               $27,829             $34,303


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 you paid a 1% sales charge, your returns would
be lower than those shown above. "If Held" results represent the percent change
in net asset value per share. NAV returns would have been lower had sales
charges been reflected. All results are historical and assume the reinvestment
of dividends and capital gains. Other share classes are available for which
performance and expenses will differ.

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

The performance table and graph do not reflect the deduction of fees and taxes
that a shareowner would pay on Fund distributions or the redemption of Fund
shares.

The Fund acquired the assets and liabilities of Pioneer Research Fund ("the
predecessor fund") on June 7, 2013. As a result of the reorganization, the
predecessor fund's performance and financial history became the performance and
financial history of the Fund. The performance of Class C shares of the Fund is
the performance of Class C shares of the predecessor fund for periods prior to
the reorganization, and has not been restated to reflect any differences in
expenses.

Please refer to the financial highlights for a more current expense ratio.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 13


Performance Update | 12/31/18                                     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 Core Equity Fund during the
periods shown, compared to that of the Standard & Poor's 500 Index.



Average Annual Total Returns
(As of December 31, 2018)
---------------------------------------------------
                    Net
                    Asset            S&P
                    Value            500
Period              (NAV)            Index
---------------------------------------------------
                               
10 years            11.78%           13.12%
5 years              6.13             8.49
1 year              -8.47            -4.38
---------------------------------------------------


Expense Ratio
(Per prospectus dated June 1, 2018)
---------------------------------------------------
                Gross
---------------------------------------------------
             
                0.56%
---------------------------------------------------


[THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL]

Value of $5 Million Investment



                                    Pioneer Core
                                    Equity Fund         S&P 500 Index
                                                  
12/08                               $ 5,000,000         $ 5,000,000
12/09                               $ 6,455,308         $ 6,323,223
12/10                               $ 7,461,206         $ 7,275,714
12/11                               $ 7,533,613         $ 7,429,362
12/12                               $ 8,626,871         $ 8,618,318
12/13                               $11,302,574         $11,409,632
12/14                               $12,482,789         $12,971,442
12/15                               $12,296,828         $13,150,944
12/16                               $13,329,181         $14,723,787
12/17                               $16,630,956         $17,938,220
12/18                               $15,221,524         $17,151,744


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 May 4, 2018, is the net asset
value performance of the Fund's Class A shares, which has not been restated to
reflect any differences in expenses, including Rule 12b-1 fees applicable to
Class A shares. Since fees for Class A shares generally are higher than those
of Class K shares, the performance of Class K shares prior to their inception
would have been higher than the performance shown. For the period beginning May
4, 2018, the actual performance of Class K shares is reflected. Class K shares
are not subject to sales charges and are available for limited groups of
eligible investors, including institutional investors. All results are
historical and assume the reinvestment of dividends and capital gains. Other
share classes are available for which performance and expenses will differ.

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

The Fund acquired the assets and liabilities of Pioneer Research Fund ("the
predecessor fund") on June 7, 2013. As a result of the reorganization, the
predecessor fund's performance and financial history became the performance and
financial history of the Fund. The performance of Class A shares of the Fund is
the performance of Class A shares of the predecessor fund for periods prior to
the reorganization, and has not been restated to reflect any differences in
expenses.

The performance table and graph do not reflect the deduction of fees and taxes
that a shareowner would pay on Fund distributions or the redemption of Fund
shares.

Please refer to the financial highlights for more recent expense ratios.

14 Pioneer Core Equity Fund | Annual Report | 12/31/18


Performance Update | 12/31/18                                     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 Core Equity Fund for the periods
shown, compared to that of the Standard & Poor's 500 Index.



Average Annual Total Returns
(As of December 31, 2018)
---------------------------------------------------
                       Net
                       Asset         S&P
                       Value         500
Period                 (NAV)         Index
---------------------------------------------------
                               
10 years               11.74%        13.12%
5 years                 6.07          8.49
1 year                 -8.76         -4.38
---------------------------------------------------


Expense Ratio
(Per prospectus dated June 1, 2018)
---------------------------------------------------
                Gross
---------------------------------------------------
             
                1.28%
---------------------------------------------------


[THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL]

Value of $10,000 Investment



                                    Pioneer Core
                                    Equity Fund         S&P 500 Index
                                                  
12/08                               $10,000             $10,000
12/09                               $12,911             $12,646
12/10                               $14,922             $14,551
12/11                               $15,067             $14,859
12/12                               $17,254             $17,237
12/13                               $22,605             $22,819
12/14                               $24,966             $25,943
12/15                               $24,594             $26,302
12/16                               $26,658             $29,448
12/17                               $33,262             $35,876
12/18                               $30,349             $34,303


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 R shares for the period prior to the
commencement of operations of Class R shares on June 29, 2018, is the net asset
value performance of the Fund's Class A shares, reduced to reflect the higher
distribution and service fees of Class R shares. For the period beginning June
29, 2018, the actual performance of Class R shares is reflected. Class R shares
are not subject to sales charges and are available for limited groups of
eligible investors, including institutional investors. All results are
historical and assume the reinvestment of dividends and capital gains. Other
share classes are available for which performance and expenses will differ.

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

The Fund acquired the assets and liabilities of Pioneer Research Fund ("the
predecessor fund") on June 7, 2013. As a result of the reorganization, the
predecessor fund's performance and financial history became the performance and
financial history of the Fund. The performance of Class A shares of the Fund is
the performance of Class A shares of the predecessor fund for periods prior to
the reorganization, and has not been restated to reflect any differences in
expenses.

The performance table and graph do not reflect the deduction of fees and taxes
that a shareowner would pay on Fund distributions or the redemption of Fund
shares.

Please refer to the financial highlights for more recent expense ratios.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 15


Performance Update | 12/31/18                                     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 Core Equity Fund during the
periods shown, compared to that of the Standard & Poor's 500 Index.



Average Annual Total Returns
(As of December 31, 2018)
---------------------------------------------------
                 Net
                 Asset              S&P
                 Value              500
Period           (NAV)              Index
---------------------------------------------------
                              
10 years         12.05%             13.12%
5 years           6.36               8.49
1 year           -8.53              -4.38
---------------------------------------------------


Expense Ratio
(Per prospectus dated June 1, 2018)
---------------------------------------------------
                Gross
---------------------------------------------------
             
                0.63%
---------------------------------------------------


[THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL]

Value of $5 Million Investment



                                    Pioneer Core
                                    Equity Fund         S&P 500 Index
                                                  
12/08                               $ 5,000,000         $ 5,000,000
12/09                               $ 6,473,135         $ 6,323,223
12/10                               $ 7,501,876         $ 7,275,714
12/11                               $ 7,592,079         $ 7,429,362
12/12                               $ 8,716,602         $ 8,618,318
12/13                               $11,461,512         $11,409,632
12/14                               $12,693,210         $12,971,442
12/15                               $12,539,223         $13,150,944
12/16                               $13,634,402         $14,723,787
12/17                               $17,056,899         $17,938,220
12/18                               $15,602,361         $17,151,744


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 Fund acquired the assets and liabilities of Pioneer Research Fund ("the
predecessor fund") on June 7, 2013. As a result of the reorganization, the
predecessor fund's performance and financial history became the performance and
financial history of the Fund. The performance of Class Y shares of the Fund is
the performance of Class Y shares of the predecessor fund for periods prior to
the reorganization, and has not been restated to reflect any differences in
expenses.

Class Y shares are not subject to sales charges and are available for limited
groups of eligible investors, including institutional investors. All results
are historical and assume the reinvestment of dividends and capital gains.
Other share classes are available for which performance and expenses will
differ.

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

The performance table and graph do not reflect the deduction of fees and taxes
that a shareowner would pay on Fund distributions or the redemption of Fund
shares.

Please refer to the financial highlights for a more current expense ratio.

16 Pioneer Core Equity Fund | Annual Report | 12/31/18


Comparing Ongoing Fund Expenses

As a shareowner in the Fund, you incur two types of costs:

(1)   ongoing costs, including management fees, distribution and/or service
      (12b-1) fees, and other Fund expenses; and

(2)   transaction costs, including sales charges (loads) on purchase payments.

This example is intended to help you understand your ongoing expenses (in
dollars) of investing in the Fund and to compare these costs with the ongoing
costs of investing in other mutual funds. The example is based on an investment
of $1,000 at the beginning of the Fund's latest six-month period and held
throughout the six months.

Using the Tables
--------------------------------------------------------------------------------
Actual Expenses

The first table below provides information about actual account values and
actual expenses. You may use the information in this table, together with the
amount you invested, to estimate the expenses that you paid over the period as
follows:

(1)   Divide your account value by $1,000
      Example: an $8,600 account value (divided by) $1,000 = 8.6

(2)   Multiply the result in (1) above by the corresponding share class's number
      in the third row under the heading entitled "Expenses Paid During Period"
      to estimate the expenses you paid on your account during this period.

Expenses Paid on a $1,000 Investment in Pioneer Core Equity Fund

Based on actual returns from July 1, 2018, through December 31, 2018.



--------------------------------------------------------------------------------------------------
Share Class                         A             C             K              R            Y
--------------------------------------------------------------------------------------------------
                                                                          
Beginning Account Value          $1,000.00     $1,000.00     $1,000.00     $1,000.00     $1,000.00
on 7/1/18
--------------------------------------------------------------------------------------------------
Ending Account Value             $  891.34     $  888.01     $  893.15     $  912.40     $  891.96
on 12/31/18
--------------------------------------------------------------------------------------------------
Expenses Paid                    $    4.29     $    8.04     $    2.72     $    5.11     $    3.05
During Period*
--------------------------------------------------------------------------------------------------


*     Expenses are equal to the Fund's annualized net expense ratio of 0.90%,
      1.69%, 0.57%, 1.06%, and 0.64% for Class A, Class C, Class K, Class R, and
      Class Y shares, respectively, multiplied by the average account value over
      the period, multiplied by 184/365 (to reflect the one-half year period).

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 17


Hypothetical Example for Comparison Purposes

The table below provides information about hypothetical account values and
hypothetical expenses based on the Fund's actual expense ratio and an assumed
rate of return of 5% per year before expenses, which is not the Fund's actual
return. The hypothetical account values and expenses may not be used to
estimate the actual ending account balance or expenses you paid for the
period.

You may use this information to compare the ongoing costs of investing in the
Fund and other funds. To do so, compare this 5% hypothetical example with the
5% hypothetical examples that appear in the shareholder reports of the other
funds.

Please note that the expenses shown in the tables are meant to highlight your
ongoing costs only and do not reflect any transaction costs, such as sales
charges (loads) that are charged at the time of the transaction. Therefore, the
table below is useful in comparing ongoing costs only and will not help you
determine the relative total costs of owning different funds. In addition, if
these transaction costs were included, your costs would have been higher.

Expenses Paid on a $1,000 Investment in Pioneer Core Equity Fund

Based on a hypothetical 5% per year return before expenses, reflecting the
period from July 1, 2018, through December 31, 2018.



--------------------------------------------------------------------------------------------------
Share Class                         A             C             K              R            Y
--------------------------------------------------------------------------------------------------
                                                                          
Beginning Account Value          $1,000.00     $1,000.00     $1,000.00     $1,000.00     $1,000.00
on 7/1/18
--------------------------------------------------------------------------------------------------
Ending Account Value             $1,020.67     $1,016.69     $1,022.33     $1,019.86     $1,021.98
on 12/31/18
--------------------------------------------------------------------------------------------------
Expenses Paid                    $    4.58     $    8.59     $    2.91     $    5.40     $    3.26
During Period*
--------------------------------------------------------------------------------------------------


*     Expenses are equal to the Fund's annualized net expense ratio of 0.90%,
      1.69%, 0.57%, 1.06%, and 0.64% for Class A, Class C, Class K, Class R, and
      Class Y shares, respectively, multiplied by the average account value over
      the period, multiplied by 184/365 (to reflect the one-half year period).

18 Pioneer Core Equity Fund | Annual Report | 12/31/18



Schedule of Investments | 12/31/18



---------------------------------------------------------------------------------------------
Shares                                                                         Value
---------------------------------------------------------------------------------------------
                                                                         
                 UNAFFILIATED ISSUERS -- 99.8%
                 COMMON STOCKS -- 99.3% of Net Assets
                 Aerospace & Defense -- 3.4%
  320,365        Raytheon Co.                                                  $   49,127,973
                                                                               --------------
                 Total Aerospace & Defense                                     $   49,127,973
---------------------------------------------------------------------------------------------
                 Air Freight & Logistics -- 1.0%
   91,208        FedEx Corp.                                                   $   14,714,587
                                                                               --------------
                 Total Air Freight & Logistics                                 $   14,714,587
---------------------------------------------------------------------------------------------
                 Auto Components -- 1.0%
  236,693        Aptiv Plc                                                     $   14,573,188
                                                                               --------------
                 Total Auto Components                                         $   14,573,188
---------------------------------------------------------------------------------------------
                 Automobiles -- 0.5%
  204,821        Harley-Davidson, Inc.                                         $    6,988,493
                                                                               --------------
                 Total Automobiles                                             $    6,988,493
---------------------------------------------------------------------------------------------
                 Banks -- 4.3%
1,249,417        Bank of America Corp.                                         $   30,785,635
  315,789        JPMorgan Chase & Co.                                              30,827,322
                                                                               --------------
                 Total Banks                                                   $   61,612,957
---------------------------------------------------------------------------------------------
                 Beverages -- 3.2%
  417,113        PepsiCo., Inc.                                                $   46,082,644
                                                                               --------------
                 Total Beverages                                               $   46,082,644
---------------------------------------------------------------------------------------------
                 Biotechnology -- 0.7%
   27,637(a)     Regeneron Pharmaceuticals, Inc.                               $   10,322,419
                                                                               --------------
                 Total Biotechnology                                           $   10,322,419
---------------------------------------------------------------------------------------------
                 Capital Markets -- 5.2%
  682,428        Intercontinental Exchange, Inc.                               $   51,407,301
  594,923        Morgan Stanley                                                    23,588,697
                                                                               --------------
                 Total Capital Markets                                         $   74,995,998
---------------------------------------------------------------------------------------------
                 Chemicals -- 1.4%
   76,747        Ecolab, Inc.                                                  $   11,308,670
   64,778        International Flavors & Fragrances, Inc.                           8,697,742
                                                                               --------------
                 Total Chemicals                                               $   20,006,412
---------------------------------------------------------------------------------------------
                 Consumer Finance -- 1.1%
  270,621        Discover Financial Services                                   $   15,961,227
                                                                               --------------
                 Total Consumer Finance                                        $   15,961,227
---------------------------------------------------------------------------------------------
                 Containers & Packaging -- 1.3%
  398,772        Ball Corp.                                                    $   18,335,537
                                                                               --------------
                 Total Containers & Packaging                                  $   18,335,537
---------------------------------------------------------------------------------------------


The accompanying notes are an integral part of these financial statements.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 19



Schedule of Investments | 12/31/18 (continued)



---------------------------------------------------------------------------------------------
Shares                                                                         Value
---------------------------------------------------------------------------------------------
                                                                         
                 Diversified Telecommunication Services -- 4.7%
2,102,693        AT&T, Inc.                                                    $   60,010,858
  463,389        CenturyLink, Inc.                                                  7,020,344
                                                                               --------------
                 Total Diversified Telecommunication Services                  $   67,031,202
---------------------------------------------------------------------------------------------
                 Electric Utilities -- 1.5%
  286,277        American Electric Power Co., Inc.                             $   21,396,343
                                                                               --------------
                 Total Electric Utilities                                      $   21,396,343
---------------------------------------------------------------------------------------------
                 Electrical Equipment -- 0.7%
  164,120        Emerson Electric Co.                                          $    9,806,170
                                                                               --------------
                 Total Electrical Equipment                                    $    9,806,170
---------------------------------------------------------------------------------------------
                 Electronic Equipment, Instruments & Components -- 1.2%
  204,274        CDW Corp.                                                     $   16,556,408
                                                                               --------------
                 Total Electronic Equipment, Instruments & Components          $   16,556,408
---------------------------------------------------------------------------------------------
                 Energy Equipment & Services -- 1.3%
  726,560        Halliburton Co.                                               $   19,311,965
                                                                               --------------
                 Total Energy Equipment & Services                             $   19,311,965
---------------------------------------------------------------------------------------------
                 Entertainment -- 2.2%
  206,074(a)     Electronic Arts, Inc.                                         $   16,261,299
  168,717(a)     Live Nation Entertainment, Inc.                                    8,309,312
  288,674        Viacom, Inc., Class B                                              7,418,922
                                                                               --------------
                 Total Entertainment                                           $   31,989,533
---------------------------------------------------------------------------------------------
                 Equity Real Estate Investment Trusts (REITs) -- 1.5%
   97,790        Liberty Property Trust                                        $    4,095,445
  282,352        Prologis, Inc.                                                    16,579,710
                                                                               --------------
                 Total Equity Real Estate Investment Trusts (REITs)            $   20,675,155
---------------------------------------------------------------------------------------------
                 Food & Staples Retailing -- 1.7%
   67,551        Costco Wholesale Corp.                                        $   13,760,814
  162,099        Walgreens Boots Alliance, Inc.                                    11,076,225
                                                                               --------------
                 Total Food & Staples Retailing                                $   24,837,039
---------------------------------------------------------------------------------------------
                 Health Care Equipment & Supplies -- 2.7%
   27,629(a)     ABIOMED, Inc.                                                 $    8,980,530
  299,911(a)     Boston Scientific Corp.                                           10,598,855
   37,519        Cooper Cos., Inc.                                                  9,548,585
  239,432(a)     Hologic, Inc.                                                      9,840,655
                                                                               --------------
                 Total Health Care Equipment & Supplies                        $   38,968,625
---------------------------------------------------------------------------------------------
                 Health Care Providers & Services -- 3.0%
   59,541        Humana, Inc.                                                  $   17,057,306
  206,126(a)     Laboratory Corp. of America Holdings                              26,046,081
                                                                               --------------
                 Total Health Care Providers & Services                        $   43,103,387
---------------------------------------------------------------------------------------------


The accompanying notes are an integral part of these financial statements.

20 Pioneer Core Equity Fund | Annual Report | 12/31/18





---------------------------------------------------------------------------------------------
Shares                                                                         Value
---------------------------------------------------------------------------------------------
                                                                         
                 Health Care Technology -- 0.6%
  150,948(a)     Cerner Corp.                                                  $    7,915,713
                                                                               --------------
                 Total Health Care Technology                                  $    7,915,713
---------------------------------------------------------------------------------------------
                 Hotels, Restaurants & Leisure -- 1.5%
  234,665        Yum! Brands, Inc.                                             $   21,570,407
                                                                               --------------
                 Total Hotels, Restaurants & Leisure                           $   21,570,407
---------------------------------------------------------------------------------------------
                 Household Products -- 2.1%
  324,432        Procter & Gamble Co.                                          $   29,821,789
                                                                               --------------
                 Total Household Products                                      $   29,821,789
---------------------------------------------------------------------------------------------
                 Insurance -- 5.9%
  455,456        Marsh & McLennan Cos., Inc.                                   $   36,322,616
  407,433        Progressive Corp.                                                 24,580,433
  286,794        Prudential Financial, Inc.                                        23,388,051
                                                                               --------------
                 Total Insurance                                               $   84,291,100
---------------------------------------------------------------------------------------------
                 Interactive Media & Services -- 4.1%
   56,356(a)     Alphabet, Inc.                                                $   58,889,766
                                                                               --------------
                 Total Interactive Media & Services                            $   58,889,766
---------------------------------------------------------------------------------------------
                 Internet & Direct Marketing Retail -- 6.0%
   37,132(a)     Amazon.com, Inc.                                              $   55,771,150
   12,376(a)     Booking Holdings, Inc.                                            21,316,670
  309,833(a)     eBay, Inc.                                                         8,697,012
                                                                               --------------
                 Total Internet & Direct Marketing Retail                      $   85,784,832
---------------------------------------------------------------------------------------------
                 IT Services -- 2.3%
  248,296        Visa, Inc.                                                    $   32,760,174
                                                                               --------------
                 Total IT Services                                             $   32,760,174
---------------------------------------------------------------------------------------------
                 Life Sciences Tools & Services -- 0.3%
    7,996(a)     Mettler-Toledo International, Inc.                            $    4,522,378
                                                                               --------------
                 Total Life Sciences Tools & Services                          $    4,522,378
---------------------------------------------------------------------------------------------
                 Machinery -- 2.6%
  270,844        Stanley Black & Decker, Inc.                                  $   32,430,860
   70,377        Xylem, Inc.                                                        4,695,553
                                                                               --------------
                 Total Machinery                                               $   37,126,413
---------------------------------------------------------------------------------------------
                 Multiline Retail -- 0.7%
   88,271        Dollar General Corp.                                          $    9,540,330
                                                                               --------------
                 Total Multiline Retail                                        $    9,540,330
---------------------------------------------------------------------------------------------
                 Oil, Gas & Consumable Fuels -- 4.2%
  197,886        EOG Resources, Inc.                                           $   17,257,638
  808,561        TOTAL SA (A.D.R.)                                                 42,190,713
                                                                               --------------
                 Total Oil, Gas & Consumable Fuels                             $   59,448,351
---------------------------------------------------------------------------------------------


The accompanying notes are an integral part of these financial statements.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 21



Schedule of Investments | 12/31/18 (continued)



---------------------------------------------------------------------------------------------
Shares                                                                         Value
---------------------------------------------------------------------------------------------
                                                                         
                 Pharmaceuticals -- 5.2%
   29,014(a)     Elanco Animal Health, Inc.                                    $      914,811
  216,384        Eli Lilly & Co.                                                   25,039,957
  386,407        Merck & Co., Inc.                                                 29,525,359
  221,378        Zoetis, Inc.                                                      18,936,674
                                                                               --------------
                 Total Pharmaceuticals                                         $   74,416,801
---------------------------------------------------------------------------------------------
                 Road & Rail -- 1.1%
  159,396        Kansas City Southern                                          $   15,214,348
                                                                               --------------
                 Total Road & Rail                                             $   15,214,348
---------------------------------------------------------------------------------------------
                 Semiconductors & Semiconductor Equipment -- 2.6%
  380,892(a)     Advanced Micro Devices, Inc.                                  $    7,031,266
  723,075(a)     Micron Technology, Inc.                                           22,943,170
  207,715        Taiwan Semiconductor Manufacturing Co., Ltd. (A.D.R.)              7,666,760
                                                                               --------------
                 Total Semiconductors & Semiconductor Equipment                $   37,641,196
---------------------------------------------------------------------------------------------
                 Software -- 7.1%
  695,705        Microsoft Corp.                                               $   70,662,757
  515,118        Oracle Corp.                                                      23,257,578
   55,450(a)     salesforce.com, Inc.                                               7,594,987
                                                                               --------------
                 Total Software                                                $  101,515,322
---------------------------------------------------------------------------------------------
                 Specialty Retail -- 2.7%
  163,919        Home Depot, Inc.                                              $   28,164,563
  238,971        TJX Cos., Inc.                                                    10,691,562
                                                                               --------------
                 Total Specialty Retail                                        $   38,856,125
---------------------------------------------------------------------------------------------
                 Technology Hardware, Storage & Peripherals -- 4.4%
  400,907        Apple, Inc.                                                   $   63,239,070
                                                                               --------------
                 Total Technology Hardware, Storage & Peripherals              $   63,239,070
---------------------------------------------------------------------------------------------
                 Trading Companies & Distributors -- 2.3%
  317,564(a)     United Rentals, Inc.                                          $   32,559,837
                                                                               --------------
                 Total Trading Companies & Distributors                        $   32,559,837
---------------------------------------------------------------------------------------------
                 TOTAL COMMON STOCKS
                 (Cost $1,416,913,200)                                         $1,421,511,214
---------------------------------------------------------------------------------------------


---------------------------------------------------------------------------------------------
Principal
Amount
USD ($)
---------------------------------------------------------------------------------------------
                                                                         
                 U.S. GOVERNMENT AND AGENCY OBLIGATION --
                 0.1% OF NET ASSETS
2,000,000(b)     U.S. Treasury Bills, 1/22/19                                  $    1,997,444
---------------------------------------------------------------------------------------------
                 TOTAL U.S. GOVERNMENT AND AGENCY OBLIGATION
                 (Cost $1,997,299)                                             $    1,997,444
---------------------------------------------------------------------------------------------


The accompanying notes are an integral part of these financial statements.

22 Pioneer Core Equity Fund | Annual Report | 12/31/18





---------------------------------------------------------------------------------------------
Principal
Amount
USD ($)                                                                        Value
---------------------------------------------------------------------------------------------
                                                                         
                 TEMPORARY CASH INVESTMENTS --
                 0.4% of Net Assets
                 REPURCHASE AGREEMENTS -- 0.4%
3,675,000        $3,675,000 ScotiaBank, 2.92%, dated 12/31/18 plus
                 accrued interest on 1/2/19 collateralized by
                 $3,749,108 Federal National Mortgage Association,
                 4.0%, 10/1/48.                                                $    3,675,000
1,895,000        $1,895,000 TD Securities USA LLC, 2.97%, dated
                 12/31/18 plus accrued interest on 1/2/19
                 collateralized by $1,932,901 Freddie Mac Giant,
                 3.5%, 7/1/46.                                                      1,895,000
                                                                               --------------
                                                                               $    5,570,000
---------------------------------------------------------------------------------------------
                 TOTAL TEMPORARY CASH INVESTMENTS
                 (Cost $5,570,000)                                             $    5,570,000
---------------------------------------------------------------------------------------------
                 TOTAL INVESTMENTS IN UNAFFILIATED ISSUERS -- 99.8%
                 (Cost $1,424,480,499)                                         $1,429,078,658
---------------------------------------------------------------------------------------------
                 OTHER ASSETS AND LIABILITIES -- 0.2%                          $    3,178,253
---------------------------------------------------------------------------------------------
                 NET ASSETS -- 100.0%                                          $1,432,256,911
=============================================================================================


REIT         Real Estate Investment Trust.

(A.D.R.)     American Depositary Receipts.

(a)          Non-income producing security.

(b)          Security issued with a zero coupon. Income is recognized through
             accretion of discount.

Purchases and sales of securities (excluding temporary cash investments) for
the year ended December 31, 2018 aggregated $1,882,348,998 and $2,003,432,316,
respectively.

The Fund is permitted to engage in purchase and sale transactions ("cross
trades") with certain funds and accounts for which Amundi Pioneer Asset
Management, Inc., (the "Adviser"), serves as the Fund's investment adviser, as
set forth in Rule 17a-7 under the Investment Company Act of 1940, pursuant to
procedures adopted by the Board of Trustees. Under these procedures, cross
trades are effected at current market prices. During the year ended December
31, 2018, the Fund did not engage in cross trade activity.

At December 31, 2018, the net unrealized appreciation on investments based on
cost for federal tax purposes of $1,425,930,197 was as follows:



                                                                                  
         Aggregate gross unrealized appreciation for all investments in which
          there is an excess of value over tax cost                                  $ 133,536,266
         Aggregate gross unrealized depreciation for all investments in which
          there is an excess of tax cost over value                                   (130,387,805)
                                                                                     -------------
         Net unrealized appreciation                                                 $   3,148,461
                                                                                     =============


The accompanying notes are an integral part of these financial statements.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 23



Schedule of Investments | 12/31/18 (continued)

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 December 31, 2018, in
valuing the Fund's investments.



------------------------------------------------------------------------------------------------------------
                                               Level 1            Level 2        Level 3    Total
------------------------------------------------------------------------------------------------------------
                                                                                
Common Stocks                                  $1,421,511,214     $       --     $ --       $1,421,511,214
U.S. Government and
 Agency Obligation                                         --      1,997,444       --            1,997,444
Repurchase Agreements                                      --      5,570,000       --            5,570,000
------------------------------------------------------------------------------------------------------------
 Total Investments in Securities               $1,421,511,214     $7,567,444     $ --       $1,429,078,658
============================================================================================================


During the year ended December 31, 2018, there were no transfers between Levels
1, 2 and 3.

The accompanying notes are an integral part of these financial statements.

24 Pioneer Core Equity Fund | Annual Report | 12/31/18


Statement of Assets and Liabilities | 12/31/18



                                                                                  
ASSETS:
  Investments in unaffiliated issuers, at value (cost $1,424,480,499)                $1,429,078,658
  Cash                                                                                    3,546,680
  Receivables --
     Fund shares sold                                                                       545,824
     Dividends                                                                            1,614,475
     Interest                                                                                   454
  Other assets                                                                               28,785
----------------------------------------------------------------------------------------------------
       Total assets                                                                  $1,434,814,876
====================================================================================================
LIABILITIES:
  Payables --
     Fund shares repurchased                                                         $    1,823,237
     Distributions                                                                           49,760
     Trustees' fees                                                                           2,244
     Transfer Agent fees                                                                    259,688
     Registration fees                                                                      120,008
     Professional fees                                                                       52,399
  Due to affiliates --
     Management fees                                                                         97,052
     Other due to affiliates                                                                 36,851
  Due to broker                                                                                  34
  Accrued expenses                                                                          116,692
----------------------------------------------------------------------------------------------------
       Total liabilities                                                             $    2,557,965
====================================================================================================
NET ASSETS:
  Paid-in capital                                                                    $1,460,428,531
  Distributable earnings (loss)                                                         (28,171,620)
----------------------------------------------------------------------------------------------------
       Net assets                                                                    $1,432,256,911
====================================================================================================
NET ASSET VALUE PER SHARE:
No par value (unlimited number of shares authorized)
  Class A (based on $1,363,459,971/85,607,873 shares)                                $        15.93
  Class C (based on $9,415,765/681,395 shares)                                       $        13.82
  Class K (based on $41,733,267/2,623,528 shares)                                    $        15.91
  Class R (based on $44,532/2,801 shares)                                            $        15.90
  Class Y (based on $17,603,376/1,090,602 shares)                                    $        16.14
MAXIMUM OFFERING PRICE PER SHARE:
  Class A (based on $15.93 net assets value per share/
     100% - 5.75% maximum sales charge)                                              $        16.90
====================================================================================================


The accompanying notes are an integral part of these financial statements.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 25


Statement of Operations
FOR THE YEAR ENDED 12/31/18



                                                                                           
INVESTMENT INCOME:
  Dividends from unaffiliated issuers (net of foreign taxes
     withheld $1,031,182)                                                  $ 28,694,645
  Interest from unaffiliated issuers                                            501,186
---------------------------------------------------------------------------------------------------------------
       Total investment income                                                                   $  29,195,831
---------------------------------------------------------------------------------------------------------------
EXPENSES:
  Management fees                                                          $  8,493,320
  Administrative expense                                                        626,894
  Transfer agent fees
     Class A                                                                  1,051,902
     Class C                                                                     11,781
     Class Y                                                                     39,363
  Distribution fees
     Class A                                                                  4,019,481
     Class C                                                                    133,541
     Class R                                                                        124
  Shareowner communications expense                                             269,576
  Custodian fees                                                                 43,286
  Registration fees                                                              91,514
  Professional fees                                                             127,578
  Printing expense                                                               46,962
  Pricing fees                                                                       94
  Trustees' fees                                                                 78,639
  Miscellaneous                                                                  81,913
---------------------------------------------------------------------------------------------------------------
     Total expenses                                                                              $  15,115,968
---------------------------------------------------------------------------------------------------------------
       Net investment income                                                                     $  14,079,863
---------------------------------------------------------------------------------------------------------------
REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS:
  Net realized gain (loss) on:
     Investments in unaffiliated issuers                                   $173,458,949
     Class actions                                                              472,546          $ 173,931,495
---------------------------------------------------------------------------------------------------------------
  Change in net unrealized appreciation (depreciation) on:
     Investments in unaffiliated issuers                                                         $(321,835,356)
---------------------------------------------------------------------------------------------------------------
  Net realized and unrealized gain (loss) on investments                                         $(147,903,861)
---------------------------------------------------------------------------------------------------------------
  Net decrease in net assets resulting from operations                                           $(133,823,998)
===============================================================================================================


The accompanying notes are an integral part of these financial statements.

26 Pioneer Core Equity Fund | Annual Report | 12/31/18


Statements of Changes in Net Assets



----------------------------------------------------------------------------------------------------------------
                                                                       Year Ended                Year Ended
                                                                       12/31/18                  12/31/17
----------------------------------------------------------------------------------------------------------------
                                                                                           
FROM OPERATIONS:
Net investment income (loss)                                           $   14,079,863            $   13,633,655
Net realized gain (loss) on investments                                   173,931,495               194,750,732
Change in net unrealized appreciation (depreciation)
  on Investments                                                         (321,835,356)              144,903,051
----------------------------------------------------------------------------------------------------------------
     Net increase (decrease) in net assets resulting
        from operations                                                $ (133,823,998)           $  353,287,438
----------------------------------------------------------------------------------------------------------------
DISTRIBUTIONS TO SHAREOWNERS:
     Class A ($3.14 and $1.86 per share, respectively)                 $ (233,691,543)           $ (137,738,497)*
     Class C ($3.00 and $1.72 per share, respectively)                     (1,717,954)               (1,191,025)*
     Class K** ($3.21 and $-- per share, respectively)                     (7,608,473)                       --
     Class R*** ($3.16 and $-- per share, respectively)                        (7,560)                       --
     Class Y ($3.17 and $1.92 per share, respectively)                     (3,167,681)               (4,532,095)*
----------------------------------------------------------------------------------------------------------------
        Total distributions to shareowners                             $ (246,193,211)           $ (143,461,617)
----------------------------------------------------------------------------------------------------------------
FROM FUND SHARE TRANSACTIONS:
Net proceeds from sales of shares                                      $  140,655,901            $   43,063,410
Reinvestment of distributions                                             228,799,836               134,434,470
Cost of shares repurchased                                               (259,838,454)             (178,805,759)
----------------------------------------------------------------------------------------------------------------
     Net increase (decrease) in net assets resulting from
        Fund share transactions                                        $  109,617,283            $   (1,307,879)
----------------------------------------------------------------------------------------------------------------
     Net increase (decrease) in net assets                             $ (270,399,926)           $  208,517,942
NET ASSETS:****
Beginning of year                                                      $1,702,656,837            $1,494,138,895
----------------------------------------------------------------------------------------------------------------
End of year                                                            $1,432,256,911            $1,702,656,837
================================================================================================================
* For the year ended December 31, 2017, distributions to shareowners were presented as follows:
Net investment income:
  Class A ($0.16 per share)                                                                      $  (12,859,971)
  Class C ($0.02 per share)                                                                             (16,042)
  Class Y ($0.22 per share)                                                                            (602,881)
Net realized gain:
  Class A ($1.70 per share)                                                                      $ (124,878,526)
  Class C ($1.70 per share)                                                                          (1,174,983)
  Class Y ($1.70 per share)                                                                          (3,929,214)


**    Class K shares commenced operations on May 4, 2018.

***   Class R shares commenced operations on June 29, 2018.

****  For the year ended December 31, 2017, undistributed net investment income
      was presented as follows: $608,764.

The accompanying notes are an integral part of these financial statements.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 27


Statements of Changes in Net Assets (continued)



--------------------------------------------------------------------------------------------------------------
                                         Year Ended        Year Ended          Year Ended       Year Ended
                                         12/31/18          12/31/18            12/31/17         12/31/17
                                         Shares            Amount              Shares           Amount
--------------------------------------------------------------------------------------------------------------
                                                                                    
Class A
Shares sold                               1,303,566        $  26,373,832        1,054,354       $  21,151,762
Reinvestment of distributions            12,709,821          224,191,051        6,475,353         131,980,574
Less shares repurchased                  (7,588,320)        (156,138,331)      (8,079,357)       (161,270,681)
--------------------------------------------------------------------------------------------------------------
     Net increase (decrease)              6,425,067        $  94,426,552         (549,650)      $  (8,138,345)
==============================================================================================================
Class C
Shares sold                                 184,961        $   3,251,927          147,371       $   2,589,340
Reinvestment of distributions               107,229            1,638,461           63,102           1,132,397
Less shares repurchased                    (375,379)          (6,949,337)        (251,028)         (4,486,141)
--------------------------------------------------------------------------------------------------------------
     Net decrease                           (83,189)       $  (2,058,949)         (40,555)      $    (764,404)
==============================================================================================================
Class K*
Shares sold                               3,470,577        $  73,585,363               --       $          --
Reinvestment of distributions                22,127              346,284               --                  --
Less shares repurchased                    (869,176)         (17,731,891)              --                  --
--------------------------------------------------------------------------------------------------------------
     Net increase                         2,623,528        $  56,199,756               --       $          --
==============================================================================================================
Class R**
Shares sold                                   2,372        $      50,000               --       $          --
Reinvestment of distributions                   429                7,560               --                  --
Less shares repurchased                          --                   --               --                  --
--------------------------------------------------------------------------------------------------------------
     Net increase                             2,801        $      57,560               --       $          --
==============================================================================================================
Class Y
Shares sold                               1,744,626        $  37,394,779          942,355       $  19,322,308
Reinvestment of distributions               146,312            2,616,480           64,010           1,321,499
Less shares repurchased                  (3,626,653)         (79,018,895)        (650,514)        (13,048,937)
--------------------------------------------------------------------------------------------------------------
     Net increase (decrease)             (1,735,715)       $ (39,007,636)         355,851       $   7,594,870
==============================================================================================================


*     Class K shares commenced operations on May 4, 2018.

**    Class R shares commenced operations on June 29, 2018.

The accompanying notes are an integral part of these financial statements.

28 Pioneer Core Equity Fund | Annual Report | 12/31/18


Financial Highlights



------------------------------------------------------------------------------------------------------------------------------------
                                                             Year            Year          Year          Year            Year
                                                             Ended           Ended         Ended         Ended           Ended
                                                             12/31/18        12/31/17      12/31/16*     12/31/15*       12/31/14*
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                          
Class A
Net asset value, beginning of period                         $    20.58      $    18.01    $    16.80    $    17.18      $    15.70
------------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations:
  Net investment income (loss)                               $     0.17(a)   $     0.17(a) $     0.19(a) $     0.13(a)   $     0.18
  Net realized and unrealized gain (loss) on investments          (1.68)           4.26          1.22         (0.39)           1.46
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations           $    (1.51)     $     4.43    $     1.41    $    (0.26)     $     1.64
------------------------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
  Net investment income                                      $    (0.14)     $    (0.16)   $    (0.20)   $    (0.12)     $    (0.16)
  Net realized gain                                               (3.00)          (1.70)           --            --              --
------------------------------------------------------------------------------------------------------------------------------------
Total distributions                                          $    (3.14)     $    (1.86)   $    (0.20)   $    (0.12)     $    (0.16)
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                   $    (4.65)     $     2.57    $     1.21    $    (0.38)     $     1.48
------------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                               $    15.93      $    20.58    $    18.01    $    16.80      $    17.18
====================================================================================================================================
Total return (b)                                                  (8.70)%(c)      24.77%         8.39%        (1.49)%(d)      10.44%
Ratio of net expenses to average net assets (e)                    0.90%           0.89%         0.94%         0.93%           0.94%
Ratio of net income (loss) to average net assets                   0.82%           0.85%         1.15%         0.75%           1.03%
Portfolio turnover rate                                             114%             81%           80%          100%             57%
Net assets, end of period (in thousands)                     $1,363,460      $1,629,908    $1,436,208    $1,450,815      $1,605,301
====================================================================================================================================


*     The Fund was audited by an independent registered public accounting firm
      other than Ernst & Young LLP.

(a)   The per-share data presented above is based on the average shares
      outstanding for the periods 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 and no sales
      charges. Total return would be reduced if sales charges were taken into
      account.

(c)   If the Fund had not recognized gains in settlement of class action
      lawsuits during the year ended December 31, 2018, the total return would
      have been (8.74)%.

(d)   If the Fund had not recognized gains in settlement of class action
      lawsuits during the year ended December 31, 2015, the total return would
      have been (1.55)%.

(e)   Includes interest expense of 0.00%, 0.00%, 0.00%, 0.00% and 0.00%+,
      respectively.

+     Amount rounds to less than 0.01%.

The accompanying notes are an integral part of these financial statements.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 29



Financial Highlights (continued)



------------------------------------------------------------------------------------------------------------------------------------
                                                                  Year          Year         Year         Year             Year
                                                                  Ended         Ended        Ended        Ended            Ended
                                                                  12/31/18      12/31/17     12/31/16*    12/31/15*        12/31/14*
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                            
Class C
Net asset value, beginning of period                              $18.26        $ 16.17      $ 15.11      $ 15.48          $ 14.19
------------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations:
  Net investment income (loss)                                    $ 0.00+(a)    $  0.01(a)   $  0.05(a)   $ (0.01)(a)(b)   $  0.02
  Net realized and unrealized gain (loss) on investments           (1.44)          3.80         1.10        (0.35)            1.33
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations                $(1.44)       $  3.81      $  1.15      $ (0.36)         $  1.35
------------------------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
  Net investment income                                           $   --        $ (0.02)     $ (0.09)     $ (0.01)         $ (0.06)
  Net realized gain                                                (3.00)         (1.70)          --           --               --
------------------------------------------------------------------------------------------------------------------------------------
Total distributions                                               $(3.00)       $ (1.72)     $ (0.09)     $ (0.01)         $ (0.06)
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                        $(4.44)       $  2.09      $  1.06      $ (0.37)         $  1.29
------------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                                    $13.82        $ 18.26      $ 16.17      $ 15.11          $ 15.48
====================================================================================================================================
Total return (c)                                                   (9.45)%(d)     23.74%        7.58%       (2.34)%(e)        9.52%
Ratio of net expenses to average net assets (f)                     1.69%          1.71%        1.76%        1.74%            1.81%
Ratio of net income (loss) to average net assets                    0.02%          0.04%        0.33%       (0.06)%           0.14%
Portfolio turnover rate                                              114%            81%          80%         100%              57%
Net assets, end of period (in thousands)                          $9,416        $13,961      $13,016      $14,106          $13,848
====================================================================================================================================


*     The Fund was audited by an independent registered public accounting firm
      other than Ernst & Young LLP.

(a)   The per-share data presented above is based on the average shares
      outstanding for the periods presented.

(b)   The amount shown for a share outstanding does not correspond with the net
      investment gain on the Statement of Operations for the period due to
      timing of the sales and repurchase of sales.

(c)   Assumes initial investment at net asset value at the beginning of each
      period, reinvestment of all distributions and 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 December 31, 2018, the total return would
      have been (9.50)%.

(e)   If the Fund had not recognized gains in settlement of class action
      lawsuits during the year ended December 31, 2015, the total return would
      have been (2.40)%.

(f)   Includes interest expense of 0.00%, 0.00%, 0.00%, 0.00% and 0.00%+,
      respectively.

+     Amount rounds to less than 0.01%.

The accompanying notes are an integral part of these financial statements.

30 Pioneer Core Equity Fund | Annual Report | 12/31/18




---------------------------------------------------------------------------------
                                                                  5/4/18* to
                                                                  12/31/18
---------------------------------------------------------------------------------
                                                               
Class K
Net asset value, beginning of period                              $ 20.82
---------------------------------------------------------------------------------
Increase (decrease) from investment operations:
  Net investment income (loss) (a)                                $  0.16
  Net realized and unrealized gain (loss) on investments            (1.86)
---------------------------------------------------------------------------------
Net increase (decrease) from investment operations                $ (1.70)
---------------------------------------------------------------------------------
Distributions to shareowners:
  Net investment income                                           $ (0.21)
  Net realized gain                                                 (3.00)
---------------------------------------------------------------------------------
Total distributions                                               $ (3.21)
---------------------------------------------------------------------------------
Net increase (decrease) in net asset value                        $ (4.91)
---------------------------------------------------------------------------------
Net asset value, end of period                                    $ 15.91
=================================================================================
Total return (b)                                                    (8.47)%(c)(d)
Ratio of net expenses to average net assets                          0.57%(e)
Ratio of net income (loss) to average net assets                     1.17%(e)
Portfolio turnover rate                                               114%(d)
Net assets, end of period (in thousands)                          $41,733
=================================================================================


*     Class K shares commenced operations on May 4, 2018.

(a)   The per-share data presented above is based on the average shares
      outstanding for the period presented.

(b)   Assumes initial investment at net asset value at the beginning of each
      period, reinvestment of all distributions and the complete redemption of
      the investment at net asset value at the end of each period.

(c)   If the Fund had not recognized gains in settlement of class action
      lawsuits during the year ended December 31, 2018, the total return would
      have been (8.51)%.

(d)   Not annualized.

(e)   Annualized.

The accompanying notes are an integral part of these financial statements.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 31


Financial Highlights (continued)



---------------------------------------------------------------------------------
                                                                   6/29/18* to
                                                                   12/31/18
---------------------------------------------------------------------------------
                                                                
Class R
Net asset value, beginning of period                               $21.08
---------------------------------------------------------------------------------
Increase (decrease) from investment operations:
  Net investment income (loss) (a)                                 $ 0.06
  Net realized and unrealized gain (loss) on investments            (2.08)
---------------------------------------------------------------------------------
Net increase (decrease) from investment operations                 $(2.02)
---------------------------------------------------------------------------------
Distributions to shareowners:
  Net investment income                                            $(0.16)
  Net realized gain                                                 (3.00)
---------------------------------------------------------------------------------
Total distributions                                                $(3.16)
---------------------------------------------------------------------------------
Net increase (decrease) in net asset value                         $(5.18)
---------------------------------------------------------------------------------
Net asset value, end of period                                     $15.90
=================================================================================
Total return (b)                                                    (8.76)%(c)(d)
Ratio of net expenses to average net assets                          1.06%(e)
Ratio of net income (loss) to average net assets                     0.62%(e)
Portfolio turnover rate                                               114%(d)
Net assets, end of period (in thousands)                           $   45
=================================================================================


*     Class R shares commenced operations on June 29, 2018.

(a)   The per-share data presented above is based on the average shares
      outstanding for the period presented.

(b)   Assumes initial investment at net asset value at the beginning of each
      period, reinvestment of all distributions and the complete redemption of
      the investment at net asset value at the end of each period.

(c)   If the Fund had not recognized gains in settlement of class action
      lawsuits during the year ended December 31, 2018, the total return would
      have been (8.80)%.

(d)   Not annualized.

(e)   Annualized.

The accompanying notes are an integral part of these financial statements.

32 Pioneer Core Equity Fund | Annual Report | 12/31/18




------------------------------------------------------------------------------------------------------------------------------------
                                                                   Year           Year         Year         Year           Year
                                                                   Ended          Ended        Ended        Ended          Ended
                                                                   12/31/18       12/31/17     12/31/16*    12/31/15*      12/31/14*
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                            
Class Y
Net asset value, beginning of period                               $ 20.80        $ 18.18      $ 16.95      $ 17.34        $ 15.85
------------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations:
  Net investment income (loss)                                     $  0.22(a)     $  0.22(a)   $  0.25(a)   $  0.19(a)     $  0.20
  Net realized and unrealized gain (loss) on investments             (1.71)          4.32         1.23        (0.40)          1.51
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations                 $ (1.49)       $  4.54      $  1.48      $ (0.21)       $  1.71
------------------------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
  Net investment income                                            $ (0.17)       $ (0.22)     $ (0.25)     $ (0.18)       $ (0.22)
  Net realized gain                                                  (3.00)         (1.70)          --           --             --
------------------------------------------------------------------------------------------------------------------------------------
Total distributions                                                $ (3.17)       $ (1.92)     $ (0.25)     $ (0.18)       $ (0.22)
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                         $ (4.66)       $  2.62      $  1.23      $ (0.39)       $  1.49
------------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                                     $ 16.14        $ 20.80      $ 18.18      $ 16.95        $ 17.34
====================================================================================================================================
Total return (b)                                                     (8.53)%(c)     25.10%        8.73%       (1.21)%(d)     10.75%
Ratio of net expenses to average net assets (e)                       0.64%          0.63%        0.63%        0.62%          0.63%
Ratio of net income (loss) to average net assets                      1.05%          1.11%        1.47%        1.07%          1.37%
Portfolio turnover rate                                                114%            81%          80%         100%            57%
Net assets, end of period (in thousands)                           $17,603        $58,788      $44,915      $62,206        $66,424
====================================================================================================================================


*     The Fund was audited by an independent registered public accounting firm
      other than Ernst & Young LLP.

(a)   The per-share data presented above is based on the average shares
      outstanding for the periods presented.

(b)   Assumes initial investment at net asset value at the beginning of each
      period, reinvestment of all distributions and the complete redemption of
      the investment at net asset value at the end of each period.

(c)   If the Fund had not recognized gains in settlement of class action
      lawsuits during the year ended December 31, 2018, the total return would
      have been (8.60)%.

(d)   If the Fund had not recognized gains in settlement of class action
      lawsuits during the year ended December 31, 2015, the total return would
      have been (1.27)%.

(e)   Includes interest expense of 0.00%, 0.00%, 0.00%, 0.00% and 0.00%+,
      respectively.

+     Amount rounds to less than 0.01%.

The accompanying notes are an integral part of these financial statements.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 33


Notes to Financial Statements | 12/31/18

1. Organization and Significant Accounting Policies

Pioneer Core Equity Fund (the "Fund") is a series of Pioneer Series Trust XI
(the "Trust"), a Delaware statutory trust. The Fund is registered under the
Investment Company Act of 1940 as a diversified, open-end management investment
company. The investment objective of the Fund is to seek long-term capital
growth.

The Fund offers six classes of shares designated as Class A, Class C, Class K,
Class R, Class T and Class Y shares. Class K and Class R commenced operations
on May 4, 2018, and June 29, 2018, respectively. Class T shares had not
commenced operations as of December 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 K and Class Y shares.

Amundi Pioneer Asset Management, Inc., an indirect wholly owned subsidiary of
Amundi and Amundi's wholly owned subsidiary, Amundi USA, Inc., serves as the
Fund's investment adviser (the "Adviser"). Amundi Pioneer Distributor, Inc., an
affiliate of Amundi Pioneer Asset Management, Inc., serves as the Fund's
distributor (the "Distributor").

In August 2018, the Securities and Exchange Commission ("SEC") released a
Disclosure Update and Simplification Final Rule. The Final Rule amends
Regulation S-X disclosures requirements to conform them to U.S. Generally
Accepted Accounting Principles ("U.S. GAAP") for investment companies. The
Fund's financial statements were prepared in compliance with the new amendments
to Regulation S-X.

34 Pioneer Core Equity Fund | Annual Report | 12/31/18



The Fund is an investment company and follows investment company accounting and
reporting guidance under U.S. GAAP. U.S. GAAP requires the management of the
Fund to make estimates and assumptions that affect the reported amounts of
assets and liabilities, the disclosure of contingent assets and liabilities at
the date of the financial statements, and the reported amounts of income,
expenses and gain or loss on investments during the reporting period. Actual
results could differ from those estimates.

The following is a summary of significant accounting policies followed by the
Fund in the preparation of its financial statements:

A.    Security Valuation

      The net asset value of the Fund is computed once daily, on each day the
      New York Stock Exchange ("NYSE") is open, as of the close of regular
      trading on the NYSE.

      Equity securities that have traded on an exchange are valued by using the
      last sale price on the principal exchange where they are traded. Equity
      securities that have not traded on the date of valuation, or securities
      for which sale prices are not available, generally are valued using the
      mean between the last bid and asked prices or, if both last bid and asked
      prices are not available, at the last quoted bid price. Last sale and bid
      and asked prices are provided by independent third party pricing services.
      In the case of equity securities not traded on an exchange, prices are
      typically determined by independent third party pricing services using a
      variety of techniques and methods.

      The value of foreign securities is translated into U.S. dollars based on
      foreign currency exchange rate quotations supplied by a third party
      pricing source. Trading in non-U.S. equity securities is substantially
      completed each day at various times prior to the close of the NYSE. The
      values of such securities used in computing the net asset value of the
      Fund's shares are determined as of such times. The Fund may use a fair
      value model developed by an independent pricing service to value non-U.S.
      equity securities.

      Fixed-income securities are valued by using prices supplied by independent
      pricing services, which consider such factors as market prices, market
      events, quotations from one or more brokers, Treasury spreads, yields,
      maturities and ratings, or may use a pricing matrix or other fair value
      methods or techniques to provide an estimated value of the security or
      instrument. A pricing matrix is a means of valuing a debt security on the
      basis of current market prices for other debt securities, historical
      trading patterns in the market for fixed-income securities and/or other
      factors. Non-U.S. debt securities that are listed on an exchange will be
      valued at the bid price obtained from an independent third party pricing
      service. When independent third party pricing services

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 35



      are unable to supply prices, or when prices or market quotations are
      considered to be unreliable, the value of that security may be determined
      using quotations from one or more broker-dealers.

      Securities for which independent pricing services or broker-dealers are
      unable to supply prices or for which market prices and/or quotations are
      not readily available or are considered to be unreliable are valued by a
      fair valuation team comprised of certain personnel of the Adviser pursuant
      to procedures adopted by the Fund's Board of Trustees. The Adviser's fair
      valuation team uses fair value methods approved by the Valuation Committee
      of the Board of Trustees. The Adviser's fair valuation team is responsible
      for monitoring developments that may impact fair valued securities and for
      discussing and assessing fair values on an ongoing basis, and at least
      quarterly, with the Valuation Committee of the Board of Trustees.

      Inputs used when applying fair value methods to value a security may
      include credit ratings, the financial condition of the company, current
      market conditions and comparable securities. The Fund may use fair value
      methods if it is determined that a significant event has occurred after
      the close of the exchange or market on which the security trades and prior
      to the determination of the Fund's net asset value. Examples of a
      significant event might include political or economic news, corporate
      restructurings, natural disasters, terrorist activity or trading halts.
      Thus, the valuation of the Fund's securities may differ significantly from
      exchange prices, and such differences could be material.

      At December 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.

36 Pioneer Core Equity Fund | Annual Report | 12/31/18



      Security transactions are recorded as of trade date. Gains and losses on
      sales of investments are calculated on the identified cost method for both
      financial reporting and federal income tax purposes.

C.    Foreign Currency Translation

      The books and records of the Fund are maintained in U.S. dollars. Amounts
      denominated in foreign currencies are translated into U.S. dollars using
      current exchange rates.

      Net realized gains and losses on foreign currency transactions, if any,
      represent, among other things, the net realized gains and losses on
      foreign currency contracts, disposition of foreign currencies and the
      difference between the amount of income accrued and the U.S. dollars
      actually received. Further, the effects of changes in foreign currency
      exchange rates on investments are not segregated on the Statement of
      Operations from the effects of changes in the market prices of those
      securities, but are included with the net realized and unrealized gain or
      loss on investments.

D.    Federal Income Taxes

      It is the Fund's policy to comply with the requirements of the Internal
      Revenue Code applicable to regulated investment companies and to
      distribute all of its net taxable income and net realized capital gains,
      if any, to its shareowners. Therefore, no provision for federal income
      taxes is required. As of December 31, 2018, the Fund did not accrue any
      interest or penalties with respect to uncertain tax positions, which, if
      applicable, would be recorded as an income tax expense on the Statement of
      Operations. Tax returns filed within the prior three years remain subject
      to examination by federal and state tax authorities.

      The amount and character of income and capital gain distributions to
      shareowners are determined in accordance with federal income tax rules,
      which may differ from U.S. GAAP. Distributions in excess of net investment
      income or net realized gains are temporary over distributions for
      financial statement purposes resulting from differences in the recognition
      or classification of income or distributions for financial statement and
      tax purposes. Capital accounts within the financial statements are
      adjusted for permanent book/tax differences to reflect tax character, but
      are not adjusted for temporary differences.

      The Fund has elected to defer $31,912,405 of capital losses recognized
      between November 1, 2018 through December 31, 2018 to its fiscal year
      ending December 31, 2019.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 37



      The tax character of distributions paid during the years ended December
      31, 2018 and December 31, 2017, were as follows:



      --------------------------------------------------------------------------
                                                        2018               2017
      --------------------------------------------------------------------------
                                                             
      Distributions paid from:
      Ordinary income                           $ 29,689,577       $ 49,980,734
      Long-term capital gain                     216,503,634         93,480,883
      --------------------------------------------------------------------------
          Total                                 $246,193,211       $143,461,617
      ==========================================================================


      The following shows the components of distributable earnings on a federal
      income tax basis at December 31, 2018:



      --------------------------------------------------------------------------
                                                                          2018
      --------------------------------------------------------------------------
                                                                
      Distributable earnings:
      Undistributed ordinary income                                $    589,310
      Undistributed long-term capital gain                                3,014
      Current year late year loss                                   (31,912,405)
      Net unrealized appreciation                                     3,148,461
      --------------------------------------------------------------------------
         Total                                                     $(28,171,620)
      ==========================================================================


      The difference between book basis and tax basis unrealized appreciation is
      attributable to the tax deferral of losses on wash sales, and tax basis
      adjustments on other holdings.

E.    Fund Shares

      The Fund records sales and repurchases of its shares as of trade date. The
      Distributor earned $49,680 in underwriting commissions on the sale of
      Class A shares during the year ended December 31, 2018.

F.    Class Allocations

      Income, common expenses and realized and unrealized gains and losses are
      calculated at the Fund level and allocated daily to each class of shares
      based on its respective percentage of adjusted net assets at the beginning
      of the day.

      Distribution fees are calculated based on the average daily net asset
      value attributable to Class A, Class C and Class R shares of the Fund,
      respectively (see Note 4). Class K and Class Y shares do not pay
      distribution fees. All expenses and fees paid to the Fund's transfer agent
      for its services are allocated among the classes of shares based on the
      number of accounts in each class and the ratable allocation of related
      out-of-pocket expenses (see Note 3).

38 Pioneer Core Equity Fund | Annual Report | 12/31/18



      Distributions to shareowners are recorded as of the ex-dividend date.
      Distributions paid by the Fund with respect to each class of shares are
      calculated in the same manner and at the same time, except that net
      investment income dividends to Class A, Class C, Class K, Class R and
      Class Y shares can reflect different transfer agent and distribution
      expense rates.

G.    Risks

      The value of securities held by the Fund may go up or down, sometimes
      rapidly or unpredictably, due to general market conditions, such as real
      or perceived adverse economic, political or regulatory conditions,
      inflation, changes in interest rates, lack of liquidity in the bond
      markets or adverse investor sentiment. In the past several years,
      financial markets have experienced increased volatility, depressed
      valuations, decreased liquidity and heightened uncertainty. These
      conditions may continue, recur, worsen or spread.

      At times, the Fund's investments may represent industries or industry
      sectors that are interrelated or have common risks, making the Fund more
      susceptible to any economic, political, or regulatory developments or
      other risks affecting those industries and sectors. The Fund's investments
      in foreign markets and countries with limited developing markets may
      subject the Fund to a greater degree of risk than investments in a
      developed market. These risks include disruptive political or economic
      conditions and the imposition of adverse governmental laws or currency
      exchange restrictions.

      With the increased use of technologies such as the Internet to conduct
      business, the Fund is susceptible to operational, information security and
      related risks. While the Fund's Adviser has established business
      continuity plans in the event of, and risk management systems to prevent,
      limit or mitigate, such cyber-attacks, there are inherent limitations in
      such plans and systems including the possibility that certain risks have
      not been identified. Furthermore, the Fund cannot control the
      cybersecurity plans and systems put in place by service providers to the
      Fund such as Brown Brothers Harriman & Co., the Fund's custodian and
      accounting agent, and DST Asset Manager Solutions, Inc., the Fund's
      transfer agent. In addition, many beneficial owners of Fund shares hold
      them through accounts at broker-dealers, retirement platforms and other
      financial market participants over which neither the Fund nor Amundi
      Pioneer exercises control. Each of these may in turn rely on service
      providers to them, which are also subject to the risk of cyber-attacks.
      Cybersecurity failures or breaches at Amundi Pioneer or the Fund's service
      providers or intermediaries have the ability to cause disruptions and
      impact business operations, potentially resulting in financial

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 39



      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.

H.    Purchased Options

      The Fund may purchase put and call options to seek to increase total
      return. Purchased call and put options entitle the Fund to buy and sell a
      specified number of shares or units of a particular security, currency or
      index at a specified price at a specific date or within a specific period
      of time. Upon the purchase of a call or put option, the premium paid by
      the Fund is included on the Statement of Assets and Liabilities as an
      investment. All premiums are marked-to-market daily, and any unrealized
      appreciation or depreciation is recorded on the Fund's Statement of
      Operations. As the purchaser of an index option, the Fund has the right to
      receive a cash payment equal to any depreciation in the value of the index
      below the strike price of the option (in the case of a put) or equal to
      any appreciation in the value of the index over the strike price of the
      option (in the case of a call) as of the valuation date of the option.
      Premiums paid for purchased call and put options which have expired are
      treated as realized losses on investments on the Statement of Operations.
      Upon the exercise or closing of a purchased put option, the premium is
      offset against the proceeds on the sale of the underlying security or
      financial instrument in order to determine the realized gain or loss on
      investments. Upon the exercise or closing of a purchased call option, the
      premium is added to the cost of the security or financial instrument. The
      risk associated with purchasing options is limited to the premium
      originally paid. The average market value of purchased options contracts
      open during the year ended December 31, 2018, was $560,637. There were no
      open purchased options contracts at December 31, 2018.

40 Pioneer Core Equity Fund | Annual Report | 12/31/18



I.    Repurchase Agreements

      Repurchase agreements are arrangements under which the Fund purchases
      securities from a broker-dealer or a bank, called the counterparty, upon
      the agreement of the counterparty to repurchase the securities from the
      Fund at a later date, and at a specific price, which is typically higher
      than the purchase price paid by the Fund. The securities purchased serve
      as the Fund's collateral for the obligation of the counterparty to
      repurchase the securities. The value of the collateral, including accrued
      interest, is required to be equal to or in excess of the repurchase price.
      The collateral for all repurchase agreements is held in safekeeping in the
      customer-only account of the Fund's custodian or a sub-custodian of the
      Fund. The Adviser is responsible for determining that the value of the
      collateral remains at least equal to the repurchase price. In the event of
      a default by the counterparty, the Fund is entitled to sell the
      securities, but the Fund may not be able to sell them for the price at
      which they were purchased, thus causing a loss to the Fund. Additionally,
      if the counterparty becomes insolvent, there is some risk that the Fund
      will not have a right to the securities, or the immediate right to sell
      the securities.

      Open repurchase agreements as of December 31, 2018 are disclosed in the
      Fund's Schedule of Investments.

2. Management Agreement

The Adviser manages the Fund's portfolio. Effective October 1, 2018, Management
fees are calculated daily at the annual rate of 0.50% of the Fund's average
daily net assets up to $5 billion and 0.45% on assets over $5 billion. Prior to
October 1, 2018, Management fees were calculated daily at the annual rate of
0.50% of the Fund's average daily net assets. For the year ended December 31,
2018, the effective management fee was equivalent to 0.50% 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
$86,401 in management fees, administrative costs and certain other
reimbursements payable to the Adviser at December 31, 2018.

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.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 41



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 December 31, 2018, such out-of-pocket expenses by class of shares were as
follows:


--------------------------------------------------------------------------------
Shareowner Communications:
--------------------------------------------------------------------------------
                                                                    
Class A                                                                $262,572
Class C                                                                   5,241
Class K                                                                      --
Class R                                                                      --
Class Y                                                                   1,763
--------------------------------------------------------------------------------
 Total                                                                 $269,576
================================================================================


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 also 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 $47,502 in distribution fees payable to the Distributor at
December 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.

In addition, redemptions of each class of shares (except Class K 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

42 Pioneer Core Equity Fund | Annual Report | 12/31/18



the original purchase of those shares. There are no CDSCs for Class K, Class R
and Class Y shares. Proceeds from the CDSCs are paid to the Distributor. For
the year ended December 31, 2018, CDSCs in the amount of $1,321 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. Prior
to August 1, 2018, the credit facility was in the amount of $195 million.
Effective August 1, 2018, the Fund participates in a credit facility that is in
the amount of $250 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
December 31, 2018 the Fund had no borrowings under the credit facility.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 43



Report of Independent Registered Public Accounting Firm

To the Board of Trustees of Pioneer Series Trust XI and the Shareholders of
Pioneer Core Equity Fund:
--------------------------------------------------------------------------------

Opinion on the Financial Statements

We have audited the accompanying statement of assets and liabilities of Pioneer
Core Equity Fund (the "Fund") (one of the funds constituting Pioneer Series
Trust XI (the "Trust")), including the schedule of investments, as of December
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 financial highlights for the year ended
December 31, 2017 (collectively referred to as the "financial statements"). The
financial highlights for the periods ended December 31, 2014, December 31, 2015
and December 31, 2016 were audited by another independent registered public
accounting firm whose report, dated February 22, 2017, expressed an
unqualified opinion on those financial highlights. In our opinion, the
financial statements present fairly, in all material respects, the financial
position of Pioneer Core Equity Fund (one of the funds constituting Pioneer
Series Trust XI) at December 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 December 31, 2017, in conformity with U.S. generally accepted
accounting principles.

Basis for Opinion

These financial statements are the responsibility of the Trust'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 Trust 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 Trust is not required to have,
nor were we engaged to perform, an audit of the Trust'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 Trust's internal
control over financial reporting. Accordingly, we express no such opinion.

44 Pioneer Core Equity Fund | Annual Report | 12/31/18



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 December 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 Trust's auditor since 2017.

Boston, Massachusetts
February 27, 2019

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 45


ADDITIONAL INFORMATION (unaudited)

For the year ended December 31, 2018, certain dividends paid by the Fund may be
subject to a maximum tax rate of 15%, as provided for by the Jobs and Growth
Tax Relief Reconciliation Act (the Act) of 2003. The Fund intends to designate
up to the maximum amount of such dividends allowable under the Act, as taxed at
a maximum rate of 15%. Complete information will be computed and reported in
conjunction with your 2018 Form 1099-DIV.

The qualifying percentage of the Fund's ordinary income dividends for the
purpose of the corporate dividends received deduction was 80.34% .

The percentages of the Fund's ordinary income distributions that are exempt
from nonresident alien (NRA) tax withholding resulting from qualified short
term gains was 56.90%.

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, 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.

46 Pioneer Core Equity Fund | Annual Report | 12/31/18


Effective immediately following the completion of the Transaction on July 3,
2017, the Board, acting upon the recommendation of the Audit Committee, engaged
an 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 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.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 47


Approval of Investment Management Agreement

Amundi Pioneer Asset Management, Inc. ("APAM") serves as the investment adviser
to Pioneer Core Equity 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

48 Pioneer Core Equity Fund | Annual Report | 12/31/18


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' regular reviews and discussions were factored into
the Trustees' deliberations concerning the renewal of the investment management
agreement.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 49


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
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 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.

50 Pioneer Core Equity Fund | Annual Report | 12/31/18


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 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.

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.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 51


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.

52 Pioneer Core Equity Fund | Annual Report | 12/31/18


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.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 53




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 - present);  Director, Broadridge Financial
Chairman of the Board       Serves until a        Chairman (2008 - 2013) and Chief Executive Officer  Solutions, Inc. (investor
and Trustee                 successor trustee is  (2008 - 2012), Quadriserv, Inc. (technology         communications and securities
                            elected or earlier    products for securities lending industry); and      processing provider for
                            retirement            Senior Executive Vice President, The Bank of New    financial services industry)
                            or removal.           York (financial and securities services)            (2009 - present); Director,
                                                  (1986 - 2004)                                       Quadriserv, Inc. (2005 -
                                                                                                      2013); and Commissioner, New
                                                                                                      Jersey State Civil Service
                                                                                                      Commission (2011 - 2015)
------------------------------------------------------------------------------------------------------------------------------------
David R. Bock (75)          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
                            successor trustee     2004 and 2008 - present); Interim Chief Executive   mortgage REIT) (2004 - 2009,
                            is elected or         Officer, Oxford Analytica, Inc. (privately held     2012 - present); Director of
                            earlier retirement    research and consulting company) (2010);            The Swiss Helvetia Fund, Inc.
                            or removal.           Executive Vice President and Chief Financial        (closed-end fund) (2010 -
                                                  Officer, I-trax, Inc. (publicly traded health       2017); Director of Oxford
                                                  care services company) (2004 - 2007); and           Analytica, Inc. (2008 -
                                                  Executive Vice President and Chief Financial        2015); and Director of
                                                  Officer, Pedestal Inc. (internet-based mortgage     Enterprise Community
                                                  trading company) (2000 - 2002); Private             Investment, Inc. (privately-
                                                  Consultant (1995 - 1997); Managing Director,        held affordable housing
                                                  Lehman Brothers (1992 - 1995); and Executive, The   finance company) (1985 - 2010)
                                                  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                                                         Mellon Institutional Funds
                            is elected or                                                             Master Portfolio (oversaw 17
                            earlier retirement                                                        portfolios in fund complex)
                            or removal.                                                               (1989 - 2008)
------------------------------------------------------------------------------------------------------------------------------------

54 Pioneer Core Equity Fund | Annual Report | 12/31/18




------------------------------------------------------------------------------------------------------------------------------------
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     firm) (1982 - present); Desautels Faculty of
                            is elected or         Management, McGill University (1999 - 2017); and
                            earlier retirement    Manager of Research Operations and Organizational
                            or removal.           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     Inc. (insurance company) (1993 - 2001); Vice
                            is elected or         President - Corporate Finance and Treasury Group,
                            earlier retirement    Citibank, N.A. (1980 - 1986 and 1990 - 1993);
                            or removal.           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 1982.   President and Chief Executive Officer, Newbury      Director of New America High
Trustee                     Serves until a        Piret Company (investment banking firm) (1981 -     Income Fund, Inc.
                            successor trustee     present)                                            (closed-end investment
                            is elected or                                                             company) (2004 - present);
                            earlier retirement                                                        and Member, Board of
                            or removal.                                                               Governors, Investment
                                                                                                      Company 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     (financial and investment company services)
                            is elected or         (1969 - 2012); Director, BNY International
                            earlier retirement    Financing Corp. (financial services) (2002 -
                            or removal.           2012); and Director, Mellon Overseas Investment
                                                  Corp. (financial services) (2009 - 2012);
                                                  Director, Financial Models (technology) (2005 -
                                                  2007); Director, BNY Hamilton Funds, Ireland
                                                  (offshore investment companies) (2004 - 2007);
                                                  Chairman/Director, AIB/BNY Securities Services
                                                  Ltd., Ireland (financial services) (1999 - 2006);
                                                  and Chairman, BNY Alternative Investment Services,
                                                  Inc. (financial services) (2005 - 2007)
------------------------------------------------------------------------------------------------------------------------------------

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 55



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          Serves until a        Asset Management USA, Inc. (since September 2014);
and Chief Executive         successor trustee     Director, CEO and President of Amundi Pioneer
Officer                     is elected or         Asset Management, Inc. (since September 2014);
                            earlier retirement    Director, CEO and President of Amundi Pioneer
                            or removal            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 2008)  None
Trustee                     Serves until a        and Chief Investment Officer, U.S. (since 2010)
                            successor trustee     of Amundi Pioneer Asset Management USA, Inc.;
                            is elected or         Executive Vice President and Chief Investment
                            earlier retirement    Officer, U.S. of Amundi Pioneer (since 2008);
                            or removal            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.

56 Pioneer Core Equity Fund | Annual Report | 12/31/18



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 (54)  Since 2003. Serves    Vice President and Associate General Counsel of     None
Secretary and Chief         at the discretion     Amundi Pioneer since January 2008; Secretary and
Legal Officer               of 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     December 2006 and Assistant Secretary of all the
                            of 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 (56)           Since 2010. Serves    Senior Counsel of Amundi Pioneer since May 2013     None
Assistant Secretary         at the discretion     and Assistant Secretary of all the Pioneer Funds
                            of the Board          since June 2010; and Counsel of Amundi Pioneer
                                                  from June 2007 to May 2013
------------------------------------------------------------------------------------------------------------------------------------
Mark E. Bradley (59)        Since 2008. Serves    Vice President - Fund Treasury of Amundi            None
Treasurer and Chief         at the discretion     Pioneer; Treasurer of all of the Pioneer Funds
Financial and               of 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     Assistant Treasurer of all of the Pioneer Funds
                            of the Board
------------------------------------------------------------------------------------------------------------------------------------
Gary Sullivan (60)          Since 2002. Serves    Senior Manager - Fund Treasury of Amundi Pioneer;   None
Assistant Treasurer         at the discretion     and Assistant Treasurer of all of the
                            of the Board          Pioneer Funds
------------------------------------------------------------------------------------------------------------------------------------

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 57



Fund Officers (continued)


------------------------------------------------------------------------------------------------------------------------------------
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 (39)       Since 2009. Serves    Senior Manager - Fund Treasury of Amundi Pioneer    None
Assistant Treasurer         at the discretion     since November 2008; Assistant Treasurer of all
                            of 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 (48)            Since 2018. Serves    Managing Director, Chief Compliance Officer of      None
Chief Compliance Officer    at the discretion     Amundi Pioneer Asset Management; Amundi Pioneer
                            of 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 of Amundi Pioneer Asset Management   None
Anti-Money                  at the discretion     and Anti-Money Laundering Officer of all the
Laundering Officer          of the Board          Pioneer Funds since 2006
------------------------------------------------------------------------------------------------------------------------------------

58 Pioneer Core Equity Fund | Annual Report | 12/31/18



                          This page is for your notes.

                          Pioneer Core Equity Fund | Annual Report | 12/31/18 59



                          This page is for your notes.

60 Pioneer Core Equity Fund | Annual Report | 12/31/18


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 219427
Kansas City, MO 64121-9427

Our toll-free fax                                                 1-800-225-4240

Our internet e-mail address               us.ask.amundipioneer@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 https://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] 2019 Amundi Pioneer Asset Management 18630-13-0219



ITEM 2. CODE OF ETHICS.

(a) Disclose whether, as of the end of the period covered by the report, the
registrant has adopted a code of ethics that applies to the registrant's
principal executive officer, principal financial officer, principal accounting
officer or controller, or persons performing similar functions, regardless of
whether these individuals are employed by the registrant or a third party.  If
the registrant has not adopted such a code of ethics, explain why it has not
done so.

The registrant has adopted, as of the end of the period covered by this report,
a code of ethics that applies to the registrant's principal executive officer,
principal financial officer, principal accounting officer and controller.

(b) For purposes of this Item, the term "code of ethics" means written standards
that are reasonably designed to deter wrongdoing and to promote:

        (1) Honest and ethical conduct, including the ethical handling of actual
        or apparent conflicts of interest between personal and professional
        relationships;

        (2) Full, fair, accurate, timely, and understandable disclosure in
        reports and documents that a registrant files with, or submits to, the
        Commission and in other public communications made by the registrant;

        (3) Compliance with applicable governmental laws, rules, and
        regulations;

        (4) The prompt internal reporting of violations of the code to an
        appropriate person or persons identified in the code; and

        (5) Accountability for adherence to the code.

(c) The registrant must briefly describe the nature of any amendment, during the
period covered by the report, to a provision of its code of ethics that applies
to the registrant's principal executive officer, principal financial officer,
principal accounting officer or controller, or persons performing similar
functions, regardless of whether these individuals are employed by the
registrant or a third party, and that relates to any element of the code of
ethics definition enumerated in paragraph (b) of this Item. The registrant must
file a copy of any such amendment as an exhibit pursuant to Item 10(a), unless
the registrant has elected to satisfy paragraph (f) of this Item by posting its
code of ethics on its website pursuant to paragraph (f)(2) of this Item, or by
undertaking to provide its code of ethics to any person without charge, upon
request, pursuant to paragraph (f)(3) of this Item.

The registrant has made no amendments to the code of ethics during the period
covered by this report.

(d) If the registrant has, during the period covered by the report, granted a
waiver, including an implicit waiver, from a provision of the code of ethics to
the registrant's principal executive officer, principal financial officer,
principal accounting officer or controller, or persons performing similar
functions, regardless of whether these individuals are employed by the
registrant or a third party, that relates to one or more of the items set forth
in paragraph (b) of this Item, the registrant must briefly describe the nature
of the waiver, the name of the person to whom the waiver was granted, and the
date of the waiver.

Not applicable.

(e) If the registrant intends to satisfy the disclosure requirement under
paragraph (c) or (d) of this Item regarding an amendment to, or a waiver from,
a provision of its code of ethics that applies to the registrant's principal
executive officer, principal financial officer, principal accounting officer or
controller, or persons performing similar functions and that relates to any
element of the code of ethics definition enumerated in paragraph (b) of this
Item by posting such information on its Internet website, disclose the
registrant's Internet address and such intention.

Not applicable.

(f) The registrant must:

        (1) File with the Commission, pursuant to Item 12(a)(1), a copy of
        its code of ethics that applies to the registrant's principal
        executive officer,principal financial officer, principal accounting
        officer or controller, or persons performing similar functions,
        as an exhibit to its annual
        report on this Form N-CSR (see attachment);

        (2) Post the text of such code of ethics on its Internet website and
        disclose, in its most recent report on this Form N-CSR, its Internet
        address and the fact that it has posted such code of ethics on its
        Internet website; or

        (3) Undertake in its most recent report on this Form N-CSR to provide to
        any person without charge, upon request, a copy of such code of ethics
        and explain the manner in which such request may be made.
	See Item 10(2)

ITEM 3. AUDIT COMMITTEE FINANCIAL EXPERT.

(a) (1)  Disclose that the registrant's board of trustees has determined that
         the registrant either:

    (i)  Has at least one audit committee financial expert serving on its audit
         committee; or

    (ii) Does not have an audit committee financial expert serving on its audit
         committee.

The registrant's Board of Trustees has determined that the registrant has at
least one audit committee financial expert.

    (2) If the registrant provides the disclosure required by paragraph
(a)(1)(i) of this Item, it must disclose the name of the audit committee
financial expert and whether that person is "independent." In order to be
considered "independent" for purposes of this Item, a member of an audit
committee may not, other than in his or her capacity as a member of the audit
committee, the board of trustees, or any other board committee:

    (i)  Accept directly or indirectly any consulting, advisory, or other
         compensatory fee from the issuer; or

    (ii) Be an "interested person" of the investment company as defined in
         Section 2(a)(19) of the Act (15 U.S.C. 80a-2(a)(19)).

Mr. David R. Bock, an independent trustee, is such an audit committee
financial expert.

    (3) If the registrant provides the disclosure required by paragraph (a)(1)
(ii) of this Item, it must explain why it does not have an audit committee
financial expert.

Not applicable.


ITEM 4. PRINCIPAL ACCOUNTANT FEES AND SERVICES.

(a) Disclose, under the caption AUDIT FEES, the aggregate fees billed for each
of the last two fiscal years for professional services rendered by the principal
accountant for the audit of the registrant's annual financial statements or
services that are normally provided by the accountant in connection with
statutory and regulatory filings or engagements for those fiscal years.

The audit fees for the Trust were $ 25,500
payable to Ernst & Young LLP for the year ended
December 31, 2018 and $25,500
for the year ended December 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 Trust were $8,028
payable to Ernst & Young LLP for the year ended
December 31, 2018 and $8,028
for the year ended December 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 Trust'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 Trust.  For the
years ended December 31 2018 and 2017, there were no
services provided to an affiliate that required the
Trust'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 Trust were $8,028
payable to Ernst & Young LLP for the year ended
December 31, 2018 and $8,028 for the year
ended December 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 Series Trust XI


By (Signature and Title)* /s/ Lisa M. Jones
Lisa M. Jones, President & Chief Executive Officer

Date March 5, 2019


Pursuant to the requirements of the Securities Exchange Act of 1934 and the
Investment Company Act of 1940, this report has been signed below by the
following persons on behalf of the registrant and in the capacities and on the
dates indicated.


By (Signature and Title)* /s/ Lisa M. Jones
Lisa M. Jones, President & Chief Executive Officer

Date March 5, 2019


By (Signature and Title)* /s/ Mark E. Bradley
Mark E. Bradley, Treasurer & Chief Accounting & Financial Officer

Date March 5, 2019

* Print the name and title of each signing officer under his or her signature.