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, 2019


Date of reporting period: January 1, 2019 through December 31, 2019


Form N-CSR is to be used by management investment companies to file reports with
the Commission not later than 10 days after the transmission to stockholders of
any report that is required to be transmitted to stockholders under Rule 30e-1
under the Investment Company Act of 1940 (17 CFR 270.30e-1).  The Commission may
use the information provided on Form N-CSR in its regulatory, disclosure review,
inspection, and policymaking roles.

A registrant is required to disclose the information specified by Form N-CSR,
and the Commission will make this information public. A registrant is not
required to respond to the collection of information contained in Form N-CSR
unless the Form displays a currently valid Office of Management and Budget
("OMB") control number. Please direct comments concerning the accuracy of the
information collection burden estimate and any suggestions for reducing the
burden to Secretary, Securities and Exchange Commission, 450 Fifth Street, NW,
Washington, DC 20549-0609.  The OMB has reviewed this collection of information
under the clearance requirements of 44 U.S.C. ss. 3507.


ITEM 1. REPORTS TO STOCKHOLDERS.



                                  Pioneer Core
                                  Equity Fund

--------------------------------------------------------------------------------
                                  Annual Report | December 31, 2019
--------------------------------------------------------------------------------

                                  Ticker Symbols:

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

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

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

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

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



                       visit us: www.amundipioneer.com/us



Table of Contents



                                                                          
President's Letter                                                            2

Portfolio Management Discussion                                               4

Portfolio Summary                                                            10

Prices and Distributions                                                     11

Performance Update                                                           12

Comparing Ongoing Fund Expenses                                              17

Schedule of Investments                                                      19

Financial Statements                                                         24

Notes to Financial Statements                                                33

Report of Independent Registered Public Accounting Firm                      42

Additional Information                                                       44

Approval of Investment Management Agreement                                  45

Trustees, Officers and Service Providers                                     50


                           Pioneer Core Equity Fund | Annual Report | 12/31/19 1



President's Letter

Dear Shareholders,

As we enter 2020 and welcome a new decade, history has taught us the importance
of taking a long-term horizon when investing, which has typically proven to be
a prudent approach to generating solid returns over time. Since 1928, our
investment process has been built on a foundation of fundamental research and
active management, principles which have guided our investment decisions for
more than 90 years. We believe active management -- that is, making active
investment decisions -- can help mitigate the potential risks during periods of
market volatility. In today's global economy, investment risk can materialize
from a number of factors, including a slowing economy, changing U.S. Federal
Reserve interest-rate policy, oil price shocks, and political and geopolitical
factors.

At Amundi Pioneer, active management begins with our own fundamental, bottom-up
research process. Our team of dedicated research analysts and portfolio
managers analyze each security under consideration, communicating directly with
the management teams of the companies issuing the securities and working
together to identify those securities that best meet our investment criteria
for our family of funds. Our risk management approach begins with each and
every security, as we strive to carefully understand the potential opportunity,
while considering any and all risk factors.

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 stress. As you consider your long-term investment
goals, we encourage you to work with your financial advisor to develop an
investment plan that paves the way for you to pursue both your short and long
term goals.

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



We greatly appreciate the trust you have placed in us and look forward to
continuing to serve you in the future.

Sincerely,

/s/ Lisa M. Jones

Lisa M. Jones
Head of the Americas, President and CEO of U.S.
Amundi Pioneer Asset Management USA, Inc.
December 31, 2019

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

                           Pioneer Core Equity Fund | Annual Report | 12/31/19 3



Portfolio Management Discussion | 12/31/19

In the following interview, Craig D. Sterling discusses the market environment
and the factors that influenced the performance of Pioneer Core Equity Fund
during the 12-month period ended December 31, 2019. Mr. Sterling, Managing
Director, Director of Core Equity and Head of Equity Research, U.S., and a
portfolio manager at Amundi Pioneer Asset Management, Inc. (Amundi Pioneer), is
responsible for the day-to-day management of the Fund's investment portfolio,
along with Ashesh "Ace" Savla, Team Leader of U.S. Equity Quantitative
Research, a vice president, and a portfolio manager at Amundi Pioneer.

Q     How did the Fund perform during the 12-month period ended December 31,
      2019?

A     Pioneer Core Equity Fund's Class A shares returned 31.41% at net asset
      value during the 12-month period ended December 31, 2019, while the Fund's
      benchmark, the Standard & Poor's 500 Index (the S&P 500), returned 31.49%.
      During the same period, the average return of the 1,387 mutual funds in
      Morningstar's Large Blend Funds category was 28.77%.

Q     How would you describe the environment for the U.S. stock market during
      the 12-month period ended December 31, 2019?

A     The Fund's benchmark, the S&P 500, posted its strongest gain in six years
      for the full 12-month period ended December 31, 2019, as investors
      responded favorably to the combination of three interest-rate cuts by the
      U.S. Federal Reserve (Fed) between July and October, consistent and
      durable growth in the U.S. economy and, later in the year, the easing of
      trade tensions between the United States and China. Corporate profits,
      while weaker compared to 2018, were strong enough to sustain the rally
      given market expectations for a recovery in earnings growth in 2020. The
      increase in stock prices in 2019 was mostly valuation-driven, as trade
      issues and a weakening economy hampered earnings growth. That fact has
      many investors concerned that the market's rally is unsustainable.
      However, if one were to combine the 2018 and 2019 returns for the S&P 500,
      the market's rally over that two-year period essentially aligns with
      corporate earnings growth rates.

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



Q     What were the most important positive contributors to the Fund's
      benchmark-relative performance during the 12-month period ended December
      31, 2019?

A     The Fund's positioning in the health care sector was a key positive
      contributor to benchmark-relative results over the 12-month period. We
      began the period with a portfolio underweight in the group, reflecting
      concerns about possible regulatory changes as well as political
      uncertainty that existed early in the year. The sector indeed
      underperformed at that time, as valuations contracted due to investors'
      worries about the potential effects "Medicare for All" legislation could
      have on health care companies should such a proposal become reality. We
      sought to capitalize on the weakness by shifting the Fund to an overweight
      stance in the sector in the latter part of the calendar year. After we
      switched to an overweight position in health care, stocks in the sector
      performed very well in the fourth quarter of 2019, and so the decision
      proved to be a further positive contributor to the Fund's
      benchmark-relative performance. While we expect additional volatility as
      the presidential election season gets underway, we believe it is best to
      focus on a combination of valuations and what potential legislative
      outcomes could actually come to fruition in the years ahead, rather than
      to get caught up in rhetoric.

      Other positive contributors to the Fund's benchmark-relative returns over
      the 12-month period were stock selection in financials and a portfolio
      overweight to the sector. Financials was home to a number of the Fund's
      top individual performers for 2019, including shares of Berkshire
      Hathaway. We maintained an overweight allocation to financials in the
      portfolio at the end of the calendar year, as we believed valuations in
      the sector remained attractive.

      Although the Fund's results in information technology were mixed overall,
      the sector included two of the leading individual positive contributors to
      relative returns for the full 12-month period: semiconductor firms Lam
      Research and Micron Technology. Semiconductor stocks surged off late-2018
      lows as investors grew increasingly optimistic regarding the outlook for
      demand, and shares of both companies performed well. Another positive
      contributor to the Fund's benchmark-relative results within information
      technology was an overweight position in Microsoft, which outpaced the
      performance of the broader sector behind steady, positive earnings.

                           Pioneer Core Equity Fund | Annual Report | 12/31/19 5



Q     What aspects of the Fund's positioning detracted from benchmark-relative
      performance during the 12-month period ended December 31, 2019?

A     Stock selection in the energy sector detracted from the Fund's
      benchmark-relative results during the 12-month period, largely due to a
      portfolio position in EOG Resources. The company has been a core holding
      in the Fund due to its above-average return on capital, favorable growth
      profile, and cost advantages driven by technological innovation. However,
      the stock fell over the 12-month period on investors' concerns about
      potential overcapacity of shale production, as well as discussions about a
      ban on fracking on federal land by Democratic presidential candidates.
      While we think such a ban is unlikely to occur, we still believe EOG's
      stock valuation is compelling even if fracking restrictions are indeed
      implemented in the years ahead. Other individual portfolio positions that
      detracted from the Fund's relative performance within energy included
      Total and Halliburton.

      In information technology, an underweight position in Apple detracted from
      the Fund's benchmark-relative performance and offset some of the benefits
      from the aforementioned investments in semiconductor stocks. Although the
      portfolio's average exposure to Apple was about three-quarters of the
      company's weighting in the S&P 500, the gap was large enough to affect
      relative returns in a negative way, given that the stock was a strong
      performer over the 12-month period. Investor excitement about potentially
      rising demand stemming from the adoption of 5G communications as well as
      continued progress in other areas of Apple's business, such as wearables
      and services, drove the sharp run-up in the stock price. We appreciate the
      large, entrenched position of Apple, but we believe its valuation more
      than captures the worth of the company.

      A position in shipping company FedEx further detracted from the Fund's
      benchmark-relative returns during the 12-month period. The company has
      struggled to demonstrate a path to sustained economic profit in the
      rapidly evolving e-commerce business in the U.S., as it has continued to
      underestimate the capital investment required to compete effectively with
      other shipping companies and to co-exist with Amazon.com. (Amazon is also
      a Fund holding.) We eliminated the Fund's FedEx position before
      period-end, as we cannot see a viable investment case, despite what seemed
      to be an attractive valuation. On the other hand, we maintained a position
      in shares of another company that underperformed the benchmark over the
      calendar year: Abiomed, a health care equipment-and-services company.
      Abiomed is the sole developer and manufacturer of a unique, life-saving
      technology for the treatment of heart failure. Abiomed's short-term
      results felt the negative effects of a need to grow its sales team, but we
      are confident in the longer-term outlook for the company, given its strong
      position in a very large, underpenetrated market.

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



Q     Did the Fund have any exposure to derivative securities during the
      12-month period ended December 31, 2019? If so, did the investments have a
      material effect on benchmark-relative results?

A     No, the Fund had no exposure to derivatives during the 12-month period.

Q     How would you characterize the Fund's positioning and your broader view on
      the markets as of December 31, 2019?

A     We believe valuations for the overall equity market are reasonable
      compared to history, once low interest rates and tame inflation levels are
      taken into consideration. With that said, we see less potential upside
      from valuation expansion going forward, meaning that corporate earnings
      will need to come through for stock prices to keep moving higher.

      In this environment, our bottom-up, fundamental investment process has led
      us to look for opportunities among stocks of higher-quality, cyclical
      companies that offer favorable valuations and lower risk profiles than the
      market as a whole. Mega-cap financial stocks represent the Fund's
      highest-conviction positioning within that area of the market, based on
      their attractive valuations and our belief that such companies can exhibit
      stable fundamentals throughout an entire business cycle.

      Health care represented the Fund's second-largest sector overweight versus
      the S&P 500 at year-end, but we have been careful to own shares of
      companies that we believe can withstand political and legislative risks.
      We think too much pessimism is priced into the sector, given the
      prevalence of companies with stable business models and compelling
      valuations. Health care stocks, therefore, appear attractively valued to
      us compared to stocks in other market segments with lower economic
      sensitivity, including utilities and consumer staples. Accordingly, the
      Fund continues to have meaningful underweights in both of those sectors.

      As always, we have sought to position the Fund where we have been
      identifying the most attractive relative values. News flows are constantly
      and rapidly changing, due to uncertainties about the global economy, trade
      conflicts, geopolitical tensions, and the upcoming 2020 U.S. Presidential
      election. We expect that politics, in particular, will be a key driver of
      market performance in the coming year. Given that the range of legislative
      outcomes is quite vast depending on the results of November's U.S.
      elections, we expect increased market volatility as investors grapple with
      potential changes to the political status quo, which could include a
      reversal of the 2017 corporate tax cut and another possible attempt at
      sweeping health care reform, among other key initiatives. That said,
      volatility and uncertainty could also create opportunities for active
      investors, and we remain on the lookout for the chance to use market
      volatility to our advantage.

                           Pioneer Core Equity Fund | Annual Report | 12/31/19 7



      We continue to rely on the combination of our experienced fundamental
      analyst team and a proprietary corporate performance and valuation
      framework grounded in business-model economics, or economic value added
      ("EVA"). We view EVA as a solid measure of profitability that incorporates
      a charge for the shareholder capital required to generate operating
      profit, in addition to neutralizing the common accounting distortions that
      appear in a company's reported net income. We believe those key
      investment-process components are critical to the success of the Fund,
      given the evolving secular and cyclical shifts taking place in nearly
      every industry, and the unstable and always evolving political and
      economic environments.

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



Please refer to the Schedule of Investments on pages 19-23 for a full listing
of Fund securities.

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

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

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

These risks may increase share price volatility.

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

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

                           Pioneer Core Equity Fund | Annual Report | 12/31/19 9



Portfolio Summary | 12/31/19

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

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



                                                                        
Information Technology                                                     19.8%
Financials                                                                 18.1%
Health Care                                                                17.8%
Communication Services                                                     13.5%
Consumer Discretionary                                                      9.5%
Industrials                                                                 7.9%
Real Estate                                                                 3.9%
Consumer Staples                                                            3.5%
Energy                                                                      2.6%
Government                                                                  1.5%
Materials                                                                   1.4%
Utilities                                                                   0.5%


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



                                                                        
 1. Microsoft Corp.                                                        6.06%
--------------------------------------------------------------------------------
 2. Alphabet, Inc.                                                         5.72
--------------------------------------------------------------------------------
 3. Berkshire Hathaway, Inc., Class B                                      4.84
--------------------------------------------------------------------------------
 4. Verizon Communications, Inc.                                           4.77
--------------------------------------------------------------------------------
 5. Amazon.com, Inc.                                                       3.91
--------------------------------------------------------------------------------
 6. Medtronic Plc                                                          3.62
--------------------------------------------------------------------------------
 7. Bank of America Corp.                                                  3.54
--------------------------------------------------------------------------------
 8. JPMorgan Chase & Co.                                                   3.10
--------------------------------------------------------------------------------
 9. Merck & Co., Inc.                                                      2.50
--------------------------------------------------------------------------------
10. Progressive Corp.                                                      2.44
--------------------------------------------------------------------------------


*     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 | 12/31/19




Prices and Distributions | 12/31/19

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



--------------------------------------------------------------------------------
       Class                  12/31/19                   12/31/18
--------------------------------------------------------------------------------
                                                    
        A                      $20.30                     $15.93
--------------------------------------------------------------------------------
        C                      $17.51                     $13.82
--------------------------------------------------------------------------------
        K*                     $20.28                     $15.91
--------------------------------------------------------------------------------
        R**                    $20.20                     $15.90
--------------------------------------------------------------------------------
        Y                      $20.59                     $16.14
--------------------------------------------------------------------------------


Distributions per Share: 1/1/19 - 12/31/19
--------------------------------------------------------------------------------



--------------------------------------------------------------------------------
                   Net Investment        Short-Term          Long-Term
       Class          Income            Capital Gains       Capital Gains
--------------------------------------------------------------------------------
                                                     
        A            $0.1496                $ --              $0.4707
--------------------------------------------------------------------------------
        C            $0.0301                $ --              $0.4707
--------------------------------------------------------------------------------
        K            $0.2139                $ --              $0.4707
--------------------------------------------------------------------------------
        R            $0.1286                $ --              $0.4707
--------------------------------------------------------------------------------
        Y            $0.1985                $ --              $0.4707
--------------------------------------------------------------------------------


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 | 12/31/19 11



Performance Update | 12/31/19                                     Class A Shares

Investment Returns
--------------------------------------------------------------------------------
The mountain chart on the right shows the change in value of a $10,000
investment made in Class A shares of Pioneer Core Equity Fund at public
offering price during the periods shown, compared to that of the Standard &
Poor's 500 Index.



Average Annual Total Returns
(As of December 31, 2019)
---------------------------------------------------
                    Net        Public
                    Asset      Offering     S&P
                    Value      Price        500
Period              (NAV)      (POP)        Index
---------------------------------------------------
                                   
10 years            11.95%     11.29%       13.56%
5 years              9.84       8.54        11.70
1 year              31.41      23.85        31.49
---------------------------------------------------


Expense Ratio
(Per prospectus dated May 1, 2019)
---------------------------------------------------
Gross
---------------------------------------------------

0.90%
---------------------------------------------------


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

Value of $10,000 Investment



                                    Pioneer Core
                                    Equity Fund         S&P 500 Index
                                                  
12/09                               $ 9,425             $10,000
12/10                               $10,894             $11,506
12/11                               $10,999             $11,749
12/12                               $12,596             $13,630
12/13                               $16,502             $18,044
12/14                               $18,225             $20,514
12/15                               $17,954             $20,798
12/16                               $19,461             $23,285
12/17                               $24,282             $28,369
12/18                               $22,170             $27,125
12/19                               $29,134             $35,666


Call 1-800-225-6292 or visit www.amundipioneer.com/us for the most recent
month-end performance results. Current performance may be lower or higher than
the performance data quoted.

The performance data quoted represents past performance, which is no guarantee
of future results. Investment return and principal value will fluctuate, and
shares, when redeemed, may be worth more or less than their original cost.

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

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

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

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

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

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



Performance Update | 12/31/19                                     Class C Shares

Investment Returns
--------------------------------------------------------------------------------
The mountain chart on the right shows the change in value of a $10,000
investment made in Class C shares of Pioneer Core Equity Fund for the periods
shown, compared to that of the Standard & Poor's 500 Index.



Average Annual Total Returns
(As of December 31, 2019)
---------------------------------------------------
                                            S&P
                    If         If           500
Period              Held       Redeemed     Index
---------------------------------------------------
                                   
10 years            10.99%     10.99%       13.56%
5 years              8.95       8.95        11.70
1 year              30.42      30.42        31.49
---------------------------------------------------


Expense Ratio
(Per prospectus dated May 1, 2019)
---------------------------------------------------
Gross
---------------------------------------------------

1.69%
---------------------------------------------------


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

Value of $10,000 Investment



                                    Pioneer Core
                                    Equity Fund         S&P 500 Index
                                                  
12/09                               $10,000             $10,000
12/10                               $11,452             $11,506
12/11                               $11,465             $11,749
12/12                               $12,998             $13,630
12/13                               $16,872             $18,044
12/14                               $18,479             $20,514
12/15                               $18,047             $20,798
12/16                               $19,414             $23,285
12/17                               $24,024             $28,369
12/18                               $21,754             $27,125
12/19                               $28,371             $35,666


Call 1-800-225-6292 or visit www.amundipioneer.com/us for the most recent
month-end performance results. Current performance may be lower or higher than
the performance data quoted.

The performance data quoted represents past performance, which is no guarantee
of future results. Investment return and principal value will fluctuate, and
shares, when redeemed, may be worth more or less than their original cost.

Class C shares held for less than one year are also subject to a 1% contingent
deferred sales charge (CDSC). If you paid a 1% sales charge, your returns would
be lower than those shown above. "If Held" results represent the percent change
in net asset value per share. NAV returns would have been lower had sales
charges been reflected. All results are historical and assume the reinvestment
of dividends and capital gains. Other share classes are available for which
performance and expenses will differ.

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

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

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

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

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 13



Performance Update | 12/31/19                                     Class K Shares

Investment Returns
--------------------------------------------------------------------------------
The mountain chart on the right shows the change in value of a $5 million
investment made in Class K shares of Pioneer Core Equity Fund during the
periods shown, compared to that of the Standard & Poor's 500 Index.



Average Annual Total Returns
(As of December 31, 2019)
---------------------------------------------------
                      Net
                      Asset      S&P
                      Value      500
Period                (NAV)      Index
---------------------------------------------------
                           
10 years              12.01%     13.56%
5 years                9.96      11.70
1 year                31.85      31.49
---------------------------------------------------


Expense Ratio
(Per prospectus dated May 1, 2019)
---------------------------------------------------
Gross
---------------------------------------------------

0.57%
---------------------------------------------------


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

Value of $5 Million Investment



                                    Pioneer Core
                                    Equity Fund         S&P 500 Index
                                                  
12/09                               $ 5,000,000         $ 5,000,000
12/10                               $ 5,779,125         $ 5,753,168
12/11                               $ 5,835,208         $ 5,874,663
12/12                               $ 6,681,998         $ 6,814,814
12/13                               $ 8,754,481         $ 9,022,006
12/14                               $ 9,668,624         $10,256,985
12/15                               $ 9,524,586         $10,398,924
12/16                               $10,324,202         $11,642,627
12/17                               $12,881,613         $14,184,395
12/18                               $11,789,928         $13,562,501
12/19                               $15,545,334         $17,832,845


Call 1-800-225-6292 or visit www.amundipioneer.com/us for the most recent
month-end performance results. Current performance may be lower or higher than
the performance data quoted.

The performance data quoted represents past performance, which is no guarantee
of future results. Investment return and principal value will fluctuate, and
shares, when redeemed, may be worth more or less than their original cost.

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

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

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

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

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

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



Performance Update | 12/31/19                                     Class R Shares

Investment Returns
--------------------------------------------------------------------------------
The mountain chart on the right shows the change in value of a $10,000
investment made in Class R shares of Pioneer Core Equity Fund for the periods
shown, compared to that of the Standard & Poor's 500 Index.



Average Annual Total Returns
(As of December 31, 2019)
---------------------------------------------------
                       Net
                       Asset      S&P
                       Value      500
Period                 (NAV)      Index
---------------------------------------------------
                            
10 years               11.90%     13.56%
5 years                 9.74      11.70
1 year                 30.90      31.49
---------------------------------------------------


Expense Ratio
(Per prospectus dated May 1, 2019)
---------------------------------------------------
Gross
---------------------------------------------------

1.06%
---------------------------------------------------


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

Value of $10,000 Investment



                                    Pioneer Core
                                    Equity Fund         S&P 500 Index
                                                  
12/09                               $10,000             $10,000
12/10                               $11,558             $11,506
12/11                               $11,670             $11,749
12/12                               $13,364             $13,630
12/13                               $17,509             $18,044
12/14                               $19,337             $20,514
12/15                               $19,049             $20,798
12/16                               $20,648             $23,285
12/17                               $25,763             $28,369
12/18                               $23,507             $27,125
12/19                               $30,770             $35,666


Call 1-800-225-6292 or visit www.amundipioneer.com/us for the most recent
month-end performance results. Current performance may be lower or higher than
the performance data quoted.

The performance data quoted represents past performance, which is no guarantee
of future results. Investment return and principal value will fluctuate, and
shares, when redeemed, may be worth more or less than their original cost.

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

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

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

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

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

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 15



Performance Update | 12/31/19                                     Class Y Shares

Investment Returns
--------------------------------------------------------------------------------
The mountain chart on the right shows the change in value of a $5 million
investment made in Class Y shares of Pioneer Core Equity Fund during the
periods shown, compared to that of the Standard & Poor's 500 Index.



Average Annual Total Returns
(As of December 31, 2019)
---------------------------------------------------
                       Net
                       Asset      S&P
                       Value      500
Period                 (NAV)      Index
---------------------------------------------------
                            
10 years               12.25%     13.56%
5 years                10.13      11.70
1 year                 31.80      31.49
---------------------------------------------------


Expense Ratio
(Per prospectus dated May 1, 2019)
----------------------------------
Gross
----------------------------------

0.64%
----------------------------------


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

Value of $5 Million Investment



                                    Pioneer Core
                                    Equity Fund         S&P 500 Index
                                                  
12/09                               $ 5,000,000         $ 5,000,000
12/10                               $ 5,794,624         $ 5,753,168
12/11                               $ 5,864,299         $ 5,874,663
12/12                               $ 6,732,907         $ 6,814,814
12/13                               $ 8,853,139         $ 9,022,006
12/14                               $ 9,804,531         $10,256,985
12/15                               $ 9,685,588         $10,398,924
12/16                               $10,531,530         $11,642,627
12/17                               $13,175,146         $14,184,395
12/18                               $12,051,627         $13,562,501
12/19                               $15,884,077         $17,832,845


Call 1-800-225-6292 or visit www.amundipioneer.com/us for the most recent
month-end performance results. Current performance may be lower or higher than
the performance data quoted.

The performance data quoted represents past performance, which is no guarantee
of future results. Investment return and principal value will fluctuate, and
shares, when redeemed, may be worth more or less than their original cost.

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

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

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

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

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

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



Comparing Ongoing Fund Expenses

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

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

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

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

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

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

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

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

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

Based on actual returns from July 1, 2019 through December 31, 2019.



-----------------------------------------------------------------------------------------------
Share Class                         A            C            K             R           Y
-----------------------------------------------------------------------------------------------
                                                                      
Beginning Account Value          $1,000.00    $1,000.00    $1,000.00    $1,000.00    $1,000.00
on 7/1/19
-----------------------------------------------------------------------------------------------
Ending Account Value             $1,106.42    $1,102.36    $1,108.17    $1,104.18    $1,107.94
on 12/31/19
-----------------------------------------------------------------------------------------------
Expenses Paid                        $4.78        $8.96        $2.98        $6.63        $3.51
During Period*
-----------------------------------------------------------------------------------------------


*     Expenses are equal to the Fund's annualized expense ratio of 0.90%, 1.69%,
      0.56%, 1.25%, and 0.66% for Class A, Class C, Class K, Class R, and Class
      Y, respectively, multiplied by the average account value over the period,
      multiplied by 184/365 (to reflect the one-half year period).

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 17



Hypothetical Example for Comparison Purposes

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

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

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

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

Based on a hypothetical 5% per year return before expenses, reflecting the
period from July 1, 2019 through December 31, 2019.



-----------------------------------------------------------------------------------------------
Share Class                         A            C            K             R           Y
-----------------------------------------------------------------------------------------------
                                                                      
Beginning Account Value          $1,000.00    $1,000.00    $1,000.00    $1,000.00    $1,000.00
on 7/1/19
-----------------------------------------------------------------------------------------------
Ending Account Value             $1,020.67    $1,016.69    $1,022.38    $1,018.90    $1,021.88
on 12/31/19
-----------------------------------------------------------------------------------------------
Expenses Paid                        $4.58        $8.59        $2.85        $6.36        $3.36
During Period*
-----------------------------------------------------------------------------------------------


*     Expenses are equal to the Fund's annualized expense ratio of 0.90%, 1.69%,
      0.56%, 1.25%, and 0.66% for Class A, Class C, Class K, Class R, and Class
      Y, respectively, multiplied by the average account value over the period,
      multiplied by 184/365 (to reflect the one-half year period).

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



Schedule of Investments | 12/31/19



-------------------------------------------------------------------------------------------------------------------
Shares                                                                                               Value
-------------------------------------------------------------------------------------------------------------------
                                                                                               
                   UNAFFILIATED ISSUERS -- 99.7%
                   COMMON STOCKS -- 97.0% of Net Assets
                   Aerospace & Defense -- 1.4%
   109,649         Raytheon Co.                                                                      $   24,094,271
                                                                                                     --------------
                   Total Aerospace & Defense                                                         $   24,094,271
-------------------------------------------------------------------------------------------------------------------
                   Auto Components -- 1.4%
    63,122         Aptiv PLC                                                                         $    5,994,696
   387,712         BorgWarner, Inc.                                                                      16,818,947
                                                                                                     --------------
                   Total Auto Components                                                             $   22,813,643
-------------------------------------------------------------------------------------------------------------------
                   Banks -- 8.8%
 1,703,546         Bank of America Corp.                                                             $   59,998,890
   377,432         JPMorgan Chase & Co.                                                                  52,614,021
   737,162         Wells Fargo & Co.                                                                     39,659,316
                                                                                                     --------------
                   Total Banks                                                                       $  152,272,227
-------------------------------------------------------------------------------------------------------------------
                   Beverages -- 1.2%
   151,846         PepsiCo., Inc.                                                                    $   20,752,793
                                                                                                     --------------
                   Total Beverages                                                                   $   20,752,793
-------------------------------------------------------------------------------------------------------------------
                   Biotechnology -- 1.4%
   190,933         AbbVie, Inc.                                                                      $   16,905,208
    23,318(a)      Biogen, Inc.                                                                           6,919,150
                                                                                                     --------------
                   Total Biotechnology                                                               $   23,824,358
-------------------------------------------------------------------------------------------------------------------
                   Capital Markets -- 0.7%
   127,567         Intercontinental Exchange, Inc.                                                   $   11,806,326
                                                                                                     --------------
                   Total Capital Markets                                                             $   11,806,326
-------------------------------------------------------------------------------------------------------------------
                   Chemicals -- 1.4%
   306,588         Dow, Inc.                                                                         $   16,779,561
    35,620         Ecolab, Inc.                                                                           6,874,304
                                                                                                     --------------
                   Total Chemicals                                                                   $   23,653,865
-------------------------------------------------------------------------------------------------------------------
                   Communications Equipment -- 1.0%
    89,890(a)      Arista Networks, Inc.                                                             $   18,283,626
                                                                                                     --------------
                   Total Communications Equipment                                                    $   18,283,626
-------------------------------------------------------------------------------------------------------------------
                   Consumer Discretionary -- 2.2%
   842,406         Comcast Corp.                                                                     $   37,882,998
                                                                                                     --------------
                   Total Consumer Discretionary                                                      $   37,882,998
-------------------------------------------------------------------------------------------------------------------
                   Diversified Telecommunication Services -- 5.2%
   638,171         CenturyLink, Inc.                                                                 $    8,430,239
 1,317,575         Verizon Communications, Inc.                                                          80,899,105
                                                                                                     --------------
                   Total Diversified Telecommunication Services                                      $   89,329,344
-------------------------------------------------------------------------------------------------------------------
                   Electric Utilities -- 0.5%
    83,292         American Electric Power Co., Inc.                                                 $    7,871,927
                                                                                                     --------------
                   Total Electric Utilities                                                          $    7,871,927
-------------------------------------------------------------------------------------------------------------------


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

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



Schedule of Investments | 12/31/19 (continued)



-------------------------------------------------------------------------------------------------------------------
Shares                                                                                               Value
-------------------------------------------------------------------------------------------------------------------
                                                                                               
                   Electronic Equipment, Instruments & Components -- 1.2%
   186,409         Amphenol Corp.                                                                    $   20,175,046
                                                                                                     --------------
                   Total Electronic Equipment, Instruments & Components                              $   20,175,046
-------------------------------------------------------------------------------------------------------------------
                   Energy Equipment & Services -- 1.2%
   524,845         Schlumberger, Ltd.                                                                $   21,098,769
                                                                                                     --------------
                   Total Energy Equipment & Services                                                 $   21,098,769
-------------------------------------------------------------------------------------------------------------------
                   Entertainment -- 0.2%
    55,725(a)      Live Nation Entertainment, Inc.                                                   $    3,982,666
                                                                                                     --------------
                   Total Entertainment                                                               $    3,982,666
-------------------------------------------------------------------------------------------------------------------
                   Equity Real Estate Investment Trusts (REITs) -- 3.9%
   282,684         Digital Realty Trust, Inc.                                                        $   33,848,582
   108,620         Essex Property Trust, Inc.                                                            32,679,413
                                                                                                     --------------
                   Total Equity Real Estate Investment Trusts (REITs)                                $   66,527,995
-------------------------------------------------------------------------------------------------------------------
                   Financials -- 1.1%
   416,744         Charles Schwab Corp.                                                              $   19,820,345
                                                                                                     --------------
                   Total Financials                                                                  $   19,820,345
-------------------------------------------------------------------------------------------------------------------
                   Food & Staples Retailing -- 2.3%
   457,490         Sysco Corp.                                                                       $   39,133,695
                                                                                                     --------------
                   Total Food & Staples Retailing                                                    $   39,133,695
-------------------------------------------------------------------------------------------------------------------
                   Health Care Equipment & Supplies -- 6.7%
    43,621(a)      ABIOMED, Inc.                                                                     $    7,441,306
    36,361(a)      Align Technology, Inc.                                                                10,146,173
    57,756         Cooper Cos., Inc.                                                                     18,556,425
   540,868         Medtronic Plc                                                                         61,361,475
   129,024         Zimmer Biomet Holdings, Inc.                                                          19,312,312
                                                                                                     --------------
                   Total Health Care Equipment & Supplies                                            $  116,817,691
-------------------------------------------------------------------------------------------------------------------
                   Health Care Providers & Services -- 2.3%
   107,536         Humana, Inc.                                                                      $   39,414,095
                                                                                                     --------------
                   Total Health Care Providers & Services                                            $   39,414,095
-------------------------------------------------------------------------------------------------------------------
                   Insurance -- 7.2%
   362,537(a)      Berkshire Hathaway, Inc., Class B                                                 $   82,114,631
   572,464         Progressive Corp.                                                                     41,440,669
                                                                                                     --------------
                   Total Insurance                                                                   $  123,555,300
-------------------------------------------------------------------------------------------------------------------
                   Interactive Media & Services -- 5.6%
    72,381(a)      Alphabet, Inc.                                                                    $   96,946,388
                                                                                                     --------------
                   Total Interactive Media & Services                                                $   96,946,388
-------------------------------------------------------------------------------------------------------------------
                   Internet & Direct Marketing Retail -- 5.1%
    35,870(a)      Amazon.com, Inc.                                                                  $   66,282,021
    10,953(a)      Booking Holdings, Inc.                                                                22,494,505
                                                                                                     --------------
                   Total Internet & Direct Marketing Retail                                          $   88,776,526
-------------------------------------------------------------------------------------------------------------------


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

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





-------------------------------------------------------------------------------------------------------------------
Shares                                                                                               Value
-------------------------------------------------------------------------------------------------------------------
                                                                                               
                   IT Services -- 4.8%
   120,791         Accenture PLC                                                                     $   25,434,961
   291,338         Cognizant Technology Solutions Corp.                                                  18,068,783
   201,052         Visa, Inc.                                                                            37,777,671
                                                                                                     --------------
                   Total IT Services                                                                 $   81,281,415
-------------------------------------------------------------------------------------------------------------------
                   Machinery -- 2.0%
   122,830         Stanley Black & Decker, Inc.                                                      $   20,357,844
   174,627         Xylem, Inc.                                                                           13,758,861
                                                                                                     --------------
                   Total Machinery                                                                   $   34,116,705
-------------------------------------------------------------------------------------------------------------------
                   Miscellaneous Manufacturers -- 1.3%
   125,707         Illinois Tool Works, Inc.                                                         $   22,580,748
                                                                                                     --------------
                   Total Miscellaneous Manufacturers                                                 $   22,580,748
-------------------------------------------------------------------------------------------------------------------
                   Oil, Gas & Consumable Fuels -- 1.3%
   267,648         EOG Resources, Inc.                                                               $   22,418,196
                                                                                                     --------------
                   Total Oil, Gas & Consumable Fuels                                                 $   22,418,196
-------------------------------------------------------------------------------------------------------------------
                   Pharmaceuticals -- 7.1%
   316,606(a)      Elanco Animal Health, Inc.                                                        $    9,324,046
   275,818         Eli Lilly & Co.                                                                       36,250,760
   466,760         Merck & Co., Inc.                                                                     42,451,822
   441,405         Novo Nordisk AS (A.D.R.)                                                              25,548,521
    62,754         Zoetis, Inc.                                                                           8,305,492
                                                                                                     --------------
                   Total Pharmaceuticals                                                             $  121,880,641
-------------------------------------------------------------------------------------------------------------------
                   Road & Rail -- 1.9%
    74,112         Kansas City Southern                                                              $   11,350,994
   105,528         Norfolk Southern Corp.                                                                20,486,151
                                                                                                     --------------
                   Total Road & Rail                                                                 $   31,837,145
-------------------------------------------------------------------------------------------------------------------
                   Semiconductors & Semiconductor Equipment -- 1.0%
   319,895(a)      Micron Technology, Inc.                                                           $   17,203,953
                                                                                                     --------------
                   Total Semiconductors & Semiconductor Equipment                                    $   17,203,953
-------------------------------------------------------------------------------------------------------------------
                   Software -- 9.0%
    86,987(a)      Adobe, Inc.                                                                       $   28,689,182
    38,663(a)      Guidewire Software, Inc.                                                               4,244,038
   651,762         Microsoft Corp.                                                                      102,782,867
   103,634(a)      salesforce.com, Inc.                                                                  16,855,034
    23,878(a)      Zendesk, Inc.                                                                          1,829,771
                                                                                                     --------------
                   Total Software                                                                    $  154,400,892
-------------------------------------------------------------------------------------------------------------------
                   Specialty Retail -- 2.9%
   142,609         Home Depot, Inc.                                                                  $   31,142,953
    92,414         Tractor Supply Co.                                                                     8,635,164
    38,463(a)      Ulta Beauty, Inc.                                                                      9,736,524
                                                                                                     --------------
                   Total Specialty Retail                                                            $   49,514,641
-------------------------------------------------------------------------------------------------------------------


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

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 21



Schedule of Investments | 12/31/19 (continued)



-------------------------------------------------------------------------------------------------------------------
Shares                                                                                               Value
-------------------------------------------------------------------------------------------------------------------
                                                                                               
                   Technology Hardware, Storage & Peripherals -- 2.5%
    90,374         Apple, Inc.                                                                       $   26,538,325
   288,181         NetApp, Inc.                                                                          17,939,267
                                                                                                     --------------
                   Total Technology Hardware, Storage & Peripherals                                  $   44,477,592
-------------------------------------------------------------------------------------------------------------------
                   Trading Companies & Distributors -- 1.2%
   124,613(a)      United Rentals, Inc.                                                              $   20,781,710
                                                                                                     --------------
                   Total Trading Companies & Distributors                                            $   20,781,710
-------------------------------------------------------------------------------------------------------------------
                   TOTAL COMMON STOCKS
                   (Cost $1,363,458,819)                                                             $1,669,327,532
-------------------------------------------------------------------------------------------------------------------


-------------------------------------------------------------------------------------------------------------------
Principal
Amount
USD ($)
-------------------------------------------------------------------------------------------------------------------
                                                                                               
                   U.S. GOVERNMENT AND AGENCY OBLIGATIONS -- 1.5%
                   of Net Assets
16,000,000(b)      U.S. Treasury Bills, 1/21/20                                                      $   15,987,587
10,000,000(b)      U.S. Treasury Bills, 2/18/20                                                           9,980,547
-------------------------------------------------------------------------------------------------------------------
                   TOTAL U.S. GOVERNMENT AND AGENCY OBLIGATIONS
                   (Cost $25,966,075)                                                                $   25,968,134
-------------------------------------------------------------------------------------------------------------------
                   TEMPORARY CASH INVESTMENTS -- 1.2% of Net Assets
                   REPURCHASE AGREEMENTS -- 1.2%
14,000,000         $14,000,000, Nova Scotia, 1.56%, dated 12/31/19 plus accrued
                   interest on 1/2/20, collateralized by $14,281,238 Federal
                   National Mortgage Association, 3.5%-4.5%, 11/1/33-9/1/49.                         $   14,000,000
 3,500,000         $3,500,000, TD Securities USA LLC, 1.55%, dated 12/31/19
                   plus accrued interest on 1/2/20, collateralized by the following:
                   $1,039,110, U.S. Treasury Bill, 12/3/20,
                   $2,530,926, U.S. Treasury Bond, 6.00%-6.625%,
                   2/15/26-2/15/27.                                                                       3,500,000
 3,500,000         $3,500,000, TD Securities USA LLC, 1.57%, dated 12/31/19
                   plus accrued interest on 1/2/20, collateralized by $3,570,000
                   Federal National Mortgage Association, 3.0%, 11/1/49.                                  3,500,000
                                                                                                     --------------
                                                                                                     $   21,000,000
-------------------------------------------------------------------------------------------------------------------
                   TOTAL TEMPORARY CASH INVESTMENTS
                   (Cost $21,000,000)                                                                $   21,000,000
-------------------------------------------------------------------------------------------------------------------
                   TOTAL INVESTMENTS IN UNAFFILIATED ISSUERS -- 99.7%
                   (Cost $1,410,424,894)                                                             $1,716,295,666
-------------------------------------------------------------------------------------------------------------------
                   OTHER ASSETS AND LIABILITIES -- 0.3%                                              $    4,651,496
-------------------------------------------------------------------------------------------------------------------
                   NET ASSETS -- 100.0%                                                              $1,720,947,162
===================================================================================================================


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

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



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
year ended December 31, 2019, aggregated $1,458,117,863 and $1,630,382,046,
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, 2019, the Fund did not engage in any cross trade activity.

At December 31, 2019, the net unrealized appreciation on investments based on
cost for federal tax purposes of $1,414,960,725 was as follows:



                                                                                      
        Aggregate gross unrealized appreciation for all investments in which
         there is an excess of value over tax cost                                       $317,129,380
        Aggregate gross unrealized depreciation for all investments in which
         there is an excess of tax cost over value                                        (15,794,439)
                                                                                         ------------
        Net unrealized appreciation                                                      $301,334,941
                                                                                         ============


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, 2019, in
valuing the Fund's investments:



---------------------------------------------------------------------------------------------------------
                                     Level 1              Level 2           Level 3       Total
---------------------------------------------------------------------------------------------------------
                                                                              
Common Stocks                        $1,669,327,532       $        --       $ --          $1,669,327,532
U.S. Government and
 Agency Obligations                              --        25,968,134         --              25,968,134
Repurchase Agreements                            --        21,000,000         --              21,000,000
---------------------------------------------------------------------------------------------------------
   Total Investments
     in Securities                   $1,669,327,532       $46,968,134       $ --          $1,716,295,666
=========================================================================================================


During the year ended December 31, 2019, there were no transfers between Levels
1, 2 and 3.

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

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 23



Statement of Assets and Liabilities | 12/31/19



                                                                                 
ASSETS:
  Investments in unaffiliated issuers, at value (cost $1,410,424,894)               $1,716,295,666
  Cash                                                                                   3,962,619
  Receivables --
     Investment securities sold                                                            383,719
     Fund shares sold                                                                      129,347
     Dividends                                                                           1,555,540
     Interest                                                                                1,189
  Other assets                                                                              25,713
--------------------------------------------------------------------------------------------------
       Total assets                                                                 $1,722,353,793
==================================================================================================
LIABILITIES:
  Payables --
     Fund shares repurchased                                                        $      617,773
     Distributions                                                                          45,930
     Administrative fees                                                                    25,247
     Professional fees                                                                      58,294
     Transfer agent fees                                                                   236,828
     Registration fees                                                                     120,008
     Shareowner communications expense                                                      21,221
  Due to affiliates --
     Management fees                                                                       175,034
     Other due to affiliates                                                                 4,220
  Accrued expenses                                                                         102,076
--------------------------------------------------------------------------------------------------
       Total liabilities                                                            $    1,406,631
==================================================================================================
NET ASSETS:
  Paid-in capital                                                                   $1,367,790,415
  Distributable earnings                                                               353,156,747
--------------------------------------------------------------------------------------------------
       Net assets                                                                   $1,720,947,162
==================================================================================================
NET ASSET VALUE PER SHARE:
No par value (unlimited number of shares authorized)
  Class A (based on $1,647,120,491/81,132,186 shares)                               $        20.30
  Class C (based on $11,207,900/640,217 shares)                                     $        17.51
  Class K (based on $36,205,714/1,785,066 shares)                                   $        20.28
  Class R (based on $141,360/6,998 shares)                                          $        20.20
  Class Y (based on $26,271,697/1,276,179 shares)                                   $        20.59
MAXIMUM OFFERING PRICE PER SHARE:
  Class A (based on $20.30 net asset value per share/100%-5.75%
     maximum sales charge)                                                          $        21.54
==================================================================================================


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

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



Statement of Operations
FOR THE YEAR ENDED 12/31/19



                                                                                   
INVESTMENT INCOME:
  Dividends from unaffiliated issuers (net of foreign taxes
     withheld $249,046)                                                $ 26,488,053
  Interest from unaffiliated issuers                                        850,020
------------------------------------------------------------------------------------------------------
       Total investment income                                                           $  27,338,073
------------------------------------------------------------------------------------------------------
EXPENSES:
  Management fees                                                      $  8,050,979
  Administrative expense                                                    586,798
  Transfer agent fees
     Class A                                                              1,030,634
     Class C                                                                  8,475
     Class K                                                                     40
     Class R                                                                    101
     Class Y                                                                 18,115
  Distribution fees
     Class A                                                              3,852,274
     Class C                                                                104,048
     Class R                                                                    428
  Shareowner communications expense                                         319,214
  Custodian fees                                                             25,380
  Registration fees                                                          96,139
  Professional fees                                                         112,331
  Printing expense                                                           57,110
  Pricing fees                                                                   28
  Trustees' fees                                                             75,969
  Miscellaneous                                                              90,875
------------------------------------------------------------------------------------------------------
     Total expenses                                                                      $  14,428,938
------------------------------------------------------------------------------------------------------
       Net investment income                                                             $  12,909,135
------------------------------------------------------------------------------------------------------
REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS:
  Net realized gain (loss) on:
     Investments in unaffiliated issuers                               $118,814,123
     Class actions                                                          246,585      $ 119,060,708
------------------------------------------------------------------------------------------------------
  Change in net unrealized appreciation (depreciation) on:
     Investments in unaffiliated issuers                               $301,272,613      $ 301,272,613
------------------------------------------------------------------------------------------------------
  Net realized and unrealized gain (loss) on investments                                 $ 420,333,321
------------------------------------------------------------------------------------------------------
  Net increase in net assets resulting from operations                                   $ 433,242,456
======================================================================================================


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

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 25



Statements of Changes in Net Assets



------------------------------------------------------------------------------------------------------------
                                                                        Year Ended           Year Ended
                                                                        12/31/19             12/31/18
------------------------------------------------------------------------------------------------------------
                                                                                       
FROM OPERATIONS:
Net investment income (loss)                                            $   12,909,135       $   14,079,863
Net realized gain (loss) on investments                                    119,060,708          173,931,495
Change in net unrealized appreciation (depreciation)
  on investments                                                           301,272,613         (321,835,356)
------------------------------------------------------------------------------------------------------------
     Net increase (decrease) in net assets resulting
       from operations                                                  $  433,242,456       $ (133,823,998)
------------------------------------------------------------------------------------------------------------
DISTRIBUTIONS TO SHAREOWNERS:
     Class A ($0.62 and $3.14 per share, respectively)                  $  (49,515,192)      $ (233,691,543)
     Class C ($0.50 and $3.00 per share, respectively)                        (312,029)          (1,717,954)
     Class K* ($0.68 and $3.21 per share, respectively)                     (1,262,342)          (7,608,473)
     Class R** ($0.60 and $3.16 per share, respectively)                        (3,107)              (7,560)
     Class Y ($0.67 and $3.17 per share, respectively)                        (821,419)          (3,167,681)
------------------------------------------------------------------------------------------------------------
       Total distributions to shareowners                               $  (51,914,089)      $ (246,193,211)
------------------------------------------------------------------------------------------------------------
FROM FUND SHARE TRANSACTIONS:
Net proceeds from sales of shares                                       $   32,472,258       $  140,655,901
Reinvestment of distributions                                               49,118,209          228,799,836
Cost of shares repurchased                                                (174,228,583)        (259,838,454)
------------------------------------------------------------------------------------------------------------
     Net increase (decrease) in net assets resulting
       from Fund share transactions                                     $  (92,638,116)      $  109,617,283
------------------------------------------------------------------------------------------------------------
     Net increase (decrease) in net assets                              $  288,690,251       $ (270,399,926)
NET ASSETS:
Beginning of year                                                       $1,432,256,911       $1,702,656,837
------------------------------------------------------------------------------------------------------------
End of year                                                             $1,720,947,162       $1,432,256,911
============================================================================================================


*     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.

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





-----------------------------------------------------------------------------------------------------------
                                          Year Ended      Year Ended         Year Ended      Year Ended
                                          12/31/19        12/31/19           12/31/18        12/31/18
                                          Shares          Amount             Shares          Amount
-----------------------------------------------------------------------------------------------------------
                                                                                 
Class A
Shares sold                                  834,735      $  15,565,764       1,303,566      $  26,373,832
Reinvestment of distributions              2,375,773         47,483,048      12,709,821        224,191,051
Less shares repurchased                   (7,686,195)      (144,032,558)     (7,588,320)      (156,138,331)
-----------------------------------------------------------------------------------------------------------
     Net increase (decrease)              (4,475,687)     $ (80,983,746)      6,425,067      $  94,426,552
===========================================================================================================
Class C
Shares sold                                   84,055      $   1,360,402         184,961      $   3,251,927
Reinvestment of distributions                 17,672            301,852         107,229          1,638,461
Less shares repurchased                     (142,905)        (2,291,000)       (375,379)        (6,949,337)
-----------------------------------------------------------------------------------------------------------
     Net decrease                            (41,178)     $    (628,746)        (83,189)     $  (2,058,949)
===========================================================================================================
Class K*
Shares sold                                  348,095      $   6,733,606       3,470,577      $  73,585,363
Reinvestment of distributions                 32,395            648,818          22,127            346,284
Less shares repurchased                   (1,218,952)       (22,255,809)       (869,176)       (17,731,891)
-----------------------------------------------------------------------------------------------------------
     Net increase (decrease)                (838,462)     $ (14,873,385)      2,623,528      $  56,199,756
===========================================================================================================
Class R**
Shares sold                                    6,472      $     119,876           2,372      $      50,000
Reinvestment of distributions                    155              3,075             429              7,560
Less shares repurchased                       (2,430)           (45,340)             --                 --
-----------------------------------------------------------------------------------------------------------
     Net increase                              4,197      $      77,611           2,801      $      57,560
===========================================================================================================
Class Y
Shares sold                                  447,310      $   8,692,610       1,744,626      $  37,394,779
Reinvestment of distributions                 33,520            681,416         146,312          2,616,480
Less shares repurchased                     (295,253)        (5,603,876)     (3,626,653)       (79,018,895)
-----------------------------------------------------------------------------------------------------------
     Net increase (decrease)                 185,577      $   3,770,150      (1,735,715)     $ (39,007,636)
===========================================================================================================


*     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.

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 27



Financial Highlights



------------------------------------------------------------------------------------------------------------------------------------
                                                                 Year        Year            Year        Year        Year
                                                                 Ended       Ended           Ended       Ended       Ended
                                                                 12/31/19    12/31/18        12/31/17    12/31/16*   12/31/15*
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                      
Class A
Net asset value, beginning of period                             $    15.93  $    20.58      $    18.01  $    16.80  $    17.18
------------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations:
  Net investment income (loss) (a)                               $     0.15  $     0.17      $     0.17  $     0.19  $     0.13
  Net realized and unrealized gain (loss) on investments               4.84       (1.68)           4.26        1.22       (0.39)
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations               $     4.99  $    (1.51)     $     4.43  $     1.41  $    (0.26)
------------------------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
  Net investment income                                          $    (0.15) $    (0.14)     $    (0.16) $    (0.20) $    (0.12)
  Net realized gain                                                   (0.47)      (3.00)          (1.70)         --          --
------------------------------------------------------------------------------------------------------------------------------------
Total distributions                                              $    (0.62) $    (3.14)     $    (1.86) $    (0.20) $    (0.12)
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                       $     4.37  $    (4.65)     $     2.57  $     1.21  $    (0.38)
------------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                                   $    20.30  $    15.93      $    20.58  $    18.01  $    16.80
====================================================================================================================================
Total return (b)                                                      31.41%      (8.70)%(c)      24.77%       8.39%      (1.49)%(d)
Ratio of net expenses to average net assets                            0.90%       0.90%           0.89%       0.94%       0.93%
Ratio of net investment income (loss) to average net assets            0.80%       0.82%           0.85%       1.15%       0.75%
Portfolio turnover rate                                                  93%        114%             81%         80%        100%
Net assets, end of period (in thousands)                         $1,647,120  $1,363,460      $1,629,908  $1,436,208  $1,450,815
====================================================================================================================================


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

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

(b)   Assumes initial investment at net asset value at the beginning of each
      period, reinvestment of all distributions, the complete redemption of the
      investment at net asset value at the end of each period and no sales
      charges. Total return would be reduced if sales charges were taken into
      account.

(c)   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)%.

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

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





------------------------------------------------------------------------------------------------------------------------------------
                                                                     Year          Year          Year       Year        Year
                                                                     Ended         Ended         Ended      Ended       Ended
                                                                     12/31/19      12/31/18      12/31/17   12/31/16*   12/31/15*
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                         
Class C
Net asset value, beginning of period                                 $ 13.82       $18.26        $ 16.17    $ 15.11     $ 15.48
------------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations:
  Net investment income (loss) (a)                                   $  0.00+      $ 0.00+       $  0.01    $  0.05     $ (0.01)(b)
  Net realized and unrealized gain (loss) on investments                4.19        (1.44)          3.80       1.10       (0.35)
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations                   $  4.19       $(1.44)       $  3.81    $  1.15     $ (0.36)
------------------------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
  Net investment income                                              $ (0.03)      $   --        $ (0.02)   $ (0.09)    $ (0.01)
  Net realized gain                                                    (0.47)       (3.00)         (1.70)        --          --
------------------------------------------------------------------------------------------------------------------------------------
Total distributions                                                  $ (0.50)      $(3.00)       $ (1.72)   $ (0.09)    $ (0.01)
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                           $  3.69       $(4.44)       $  2.09    $  1.06     $ (0.37)
------------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                                       $ 17.51       $13.82        $ 18.26    $ 16.17     $ 15.11
====================================================================================================================================
Total return (c)                                                       30.42%(d)    (9.45)%(e)     23.74%      7.58%      (2.34)%(f)
Ratio of net expenses to average net assets                             1.69%        1.69%          1.71%      1.76%       1.74%
Ratio of net investment income (loss) to average net assets             0.01%        0.02%          0.04%      0.33%      (0.06)%
Portfolio turnover rate                                                   93%         114%            81%        80%        100%
Net assets, end of period (in thousands)                             $11,208       $9,416        $13,961    $13,016     $14,106
====================================================================================================================================


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

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

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

(c)   Assumes initial investment at net asset value at the beginning of each
      period, reinvestment of all distributions, the complete redemption of the
      investment at net asset value at the end of each period and no sales
      charges. Total return would be reduced if sales charges were taken into
      account.

(d)   If the Fund had not recognized gains in settlement of class action
      lawsuits during the year ended December 31, 2019, the total return would
      have been 30.35%.

(e)   If the Fund had not recognized gains in settlement of class action
      lawsuits during the year ended December 31, 2018, the total return would
      have been (9.50)%.

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

+     Amount rounds to less than 0.01%.

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

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 29



Financial Highlights (continued)



------------------------------------------------------------------------------------------------------------------
                                                                                   Year Ended      5/4/18* to
                                                                                   12/31/19        12/31/18
------------------------------------------------------------------------------------------------------------------
                                                                                             
Class K
Net asset value, beginning of period                                               $ 15.91         $ 20.82
------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations:
  Net investment income (loss) (a)                                                 $  0.21         $  0.16
  Net realized and unrealized gain (loss) on investments                              4.84           (1.86)
------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations                                 $  5.05         $ (1.70)
------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
  Net investment income                                                            $ (0.21)        $ (0.21)
  Net realized gain                                                                  (0.47)          (3.00)
------------------------------------------------------------------------------------------------------------------
Total distributions                                                                $ (0.68)        $ (3.21)
------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                                         $  4.37         $ (4.91)
------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                                                     $ 20.28         $ 15.91
==================================================================================================================
Total return (b)                                                                     31.85%          (8.47)%(c)(d)
Ratio of net expenses to average net assets                                           0.56%           0.57%(e)
Ratio of net investment income (loss) to average net assets                           1.15%           1.17%(e)
Portfolio turnover rate                                                                 93%            114%(d)
Net assets, end of period (in thousands)                                           $36,206         $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.

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





------------------------------------------------------------------------------------------------------------------
                                                                                Year Ended          6/29/18* to
                                                                                12/31/19            12/31/18
------------------------------------------------------------------------------------------------------------------
                                                                                              
Class R
Net asset value, beginning of period                                            $15.90              $21.08
------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations:
  Net investment income (loss) (a)                                              $ 0.08              $ 0.06
  Net realized and unrealized gain (loss) on investments                          4.82               (2.08)
------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations                              $ 4.90              $(2.02)
------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
  Net investment income                                                         $(0.13)             $(0.16)
  Net realized gain                                                              (0.47)              (3.00)
------------------------------------------------------------------------------------------------------------------
Total distributions                                                             $(0.60)             $(3.16)
------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                                      $ 4.30              $(5.18)
------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                                                  $20.20              $15.90
==================================================================================================================
Total return (b)                                                                 30.90%              (8.76)%(c)(d)
Ratio of net expenses to average net assets                                       1.25%               1.06%(e)
Ratio of net investment income (loss) to average net assets                       0.43%               0.62%(e)
Portfolio turnover rate                                                             93%                114%(d)
Net assets, end of period (in thousands)                                        $  141              $   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.

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



Financial Highlights (continued)



------------------------------------------------------------------------------------------------------------------------------------
                                                                    Year          Year           Year       Year        Year
                                                                    Ended         Ended          Ended      Ended       Ended
                                                                    12/31/19      12/31/18       12/31/17   12/31/16*   12/31/15*
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                         
Class Y
Net asset value, beginning of period                                $ 16.14       $ 20.80        $ 18.18    $ 16.95     $ 17.34
------------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations:
  Net investment income (loss) (a)                                  $  0.20       $  0.22        $  0.22    $  0.25     $  0.19
  Net realized and unrealized gain (loss) on investments               4.92         (1.71)          4.32       1.23       (0.40)
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations                  $  5.12       $ (1.49)       $  4.54    $  1.48     $ (0.21)
------------------------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
  Net investment income                                             $ (0.20)      $ (0.17)       $ (0.22)   $ (0.25)    $ (0.18)
  Net realized gain                                                   (0.47)        (3.00)         (1.70)        --          --
------------------------------------------------------------------------------------------------------------------------------------
Total distributions                                                 $ (0.67)      $ (3.17)       $ (1.92)   $ (0.25)    $ (0.18)
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                          $  4.45       $ (4.66)       $  2.62    $  1.23     $ (0.39)
------------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                                      $ 20.59       $ 16.14        $ 20.80    $ 18.18     $ 16.95
====================================================================================================================================
Total return (b)                                                      31.80%(c)     (8.53)%(d)     25.10%      8.73%      (1.21)%(e)
Ratio of net expenses to average net assets                            0.66%         0.64%          0.63%      0.63%       0.62%
Ratio of net investment income (loss) to average net assets            1.03%         1.05%          1.11%      1.47%       1.07%
Portfolio turnover rate                                                  93%          114%            81%        80%        100%
Net assets, end of period (in thousands)                            $26,272       $17,603        $58,788    $44,915     $62,206
====================================================================================================================================


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

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

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

(c)   If the Fund had not recognized gains in settlement of class action
      lawsuits during the year ended December 31, 2019, the total return would
      have been 31.74%.

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

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

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

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



Notes to Financial Statements | 12/31/19

1. Organization and Significant Accounting Policies

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

The Fund offers five classes of shares designated as Class A, Class C, Class K,
Class R and Class Y shares. Class K and Class R commenced operations on May 4,
2018, and June 29, 2018, respectively. Each class of shares represents an
interest in the same portfolio of investments of the Fund and has identical
rights (based on relative net asset values) to assets and liquidation proceeds.
Share classes can bear different rates of class-specific fees and expenses,
such as transfer agent and distribution fees. Differences in class-specific
fees and expenses will result in differences in net investment income and,
therefore, the payment of different dividends from net investment income earned
by each class. The Amended and Restated Declaration of Trust of the Fund gives
the Board of Trustees the flexibility to specify either per-share voting or
dollar-weighted voting when submitting matters for shareowner approval. Under
per-share voting, each share of a class of the Fund is entitled to one vote.
Under dollar-weighted voting, a shareowner's voting power is determined not by
the number of shares owned, but by the dollar value of the shares on the record
date. Each share class has exclusive voting rights with respect to matters
affecting only that class, including with respect to the distribution plan for
that class. There is no distribution plan for Class K and Class Y shares.

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

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

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 33



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

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

A.    Security Valuation

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

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

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

      Repurchase agreements are valued at par. Cash may include overnight time
      deposits at approved financial institutions.

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



      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, 2019, no securities were valued using fair value methods
      (other than securities valued using prices supplied by independent pricing
      services, broker-dealers or using a third party insurance industry pricing
      model).

B.    Investment Income and Transactions

      Dividend income is recorded on the ex-dividend date, except that certain
      dividends from foreign securities where the ex-dividend date may have
      passed are recorded as soon as the Fund becomes aware of the ex-dividend
      data in the exercise of reasonable diligence.

      Interest income, including interest on income-bearing cash accounts, is
      recorded on the accrual basis. Dividend and interest income are reported
      net of unrecoverable foreign taxes withheld at the applicable country
      rates and net of income accrued on defaulted securities.

      Interest and dividend income payable by delivery of additional shares is
      reclassified as PIK (payment-in-kind) income upon receipt and is included
      in interest and dividend income, respectively.

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

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 35



C.    Federal Income Taxes

      It is the Fund's policy to comply with the requirements of the Internal
      Revenue Code applicable to regulated investment companies and to
      distribute all of its net taxable income and net realized capital gains,
      if any, to its shareowners. Therefore, no provision for federal income
      taxes is required. As of December 31, 2019, 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 tax character of distributions paid during the years ended December
      31, 2019 and December 31, 2018, were as follows:



      --------------------------------------------------------------------------
                                                         2019             2018
      --------------------------------------------------------------------------
                                                             
      Distributions paid from:
      Ordinary income                              $12,723,309     $ 29,689,577
      Long-term capital gain                        39,190,780      216,503,634
      --------------------------------------------------------------------------
          Total                                    $51,914,089     $246,193,211
      ==========================================================================


      The following shows the components of distributable earnings (losses) on a
      federal income tax basis at December 31, 2019:



      --------------------------------------------------------------------------
                                                                          2019
      --------------------------------------------------------------------------
                                                                
      Distributable earnings:
      Undistributed ordinary income                                $    579,260
      Undistributed long-term capital gain                           51,242,546
      Net unrealized appreciation                                   301,334,941
      --------------------------------------------------------------------------
          Total                                                    $353,156,747
      ==========================================================================


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

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



D.    Fund Shares

      The Fund records sales and repurchases of its shares as of trade date. The
      Distributor earned $38,815 in underwriting commissions on the sale of
      Class A shares during the year ended December 31, 2019.

E.    Class Allocations

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

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

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

F.    Risks

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

      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.

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 37



      With the increased use of technologies such as the Internet to conduct
      business, the Fund is susceptible to operational, information security and
      related risks. While the Fund's Adviser has established business
      continuity plans in the event of, and risk management systems to prevent,
      limit or mitigate, such cyber-attacks, there are inherent limitations in
      such plans and systems, including the possibility that certain risks have
      not been identified. Furthermore, the Fund cannot control the
      cybersecurity plans and systems put in place by service providers to the
      Fund such as Brown Brothers Harriman & Co., the Fund's custodian and
      accounting agent, and DST Asset Manager Solutions, Inc., the Fund's
      transfer agent. In addition, many beneficial owners of Fund shares hold
      them through accounts at broker-dealers, retirement platforms and other
      financial market participants over which neither the Fund nor Amundi
      Pioneer exercises control. Each of these may in turn rely on service
      providers to them, which are also subject to the risk of cyber-attacks.
      Cybersecurity failures or breaches at Amundi Pioneer or the Fund's service
      providers or intermediaries have the ability to cause disruptions and
      impact business operations, potentially resulting in financial losses,
      interference with the Fund's ability to calculate its net asset value,
      impediments to trading, the inability of Fund shareowners to effect share
      purchases, redemptions or exchanges or receive distributions, loss of or
      unauthorized access to private shareowner information and violations of
      applicable privacy and other laws, regulatory fines, penalties,
      reputational damage, or additional compliance costs. Such costs and losses
      may not be covered under any insurance. In addition, maintaining vigilance
      against cyber-attacks may involve substantial costs over time, and system
      enhancements may themselves be subject to cyber-attacks.

      The Fund's prospectus contains unaudited information regarding the Fund's
      principal risks. Please refer to that document when considering the Fund's
      principal risks.

G.    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

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



      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 at December 31, 2019, are disclosed in the
      Schedule of Investments.

2. Management Agreement

The Adviser manages the Fund's portfolio. 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% of the Fund's average daily net assets over $5 billion.
For the year ended December 31, 2019, the net 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
$121,157 in management fees, administrative costs and certain other
reimbursements payable to the Adviser at December 31, 2019.

3. Transfer Agent

DST Asset Manager Solutions, Inc. serves as the transfer agent to the Fund at
negotiated rates. Transfer agent fees and payables shown on the Statement of
Operations and the Statement of Assets and Liabilities, respectively, include
sub-transfer agent expenses incurred through the Fund's omnibus relationship
contracts.

In addition, the Fund reimbursed the transfer agent for out-of-pocket expenses
incurred by the transfer agent related to shareowner communications activities
such as proxy and statement mailings, and outgoing phone calls. For the year
ended December 31, 2019, such out-of-pocket expenses by class of shares were as
follows:



--------------------------------------------------------------------------------
Shareowner Communications:
--------------------------------------------------------------------------------
                                                                    
Class A                                                                $313,071
Class C                                                                   4,650
Class K                                                                      18
Class R                                                                      58
Class Y                                                                   1,417
--------------------------------------------------------------------------------
 Total                                                                 $319,214
================================================================================


                          Pioneer Core Equity Fund | Annual Report | 12/31/19 39



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 $58,097 in distribution fees payable to the Distributor at
December 31, 2019.

The Fund also has adopted a separate service plan for Class R shares (the
"Service Plan"). The Service Plan authorizes the Fund to pay securities
dealers, plan administrators or other service organizations that agree to
provide certain services to retirement plans or plan participants holding
shares of the Fund a service fee of up to 0.25% of the Fund's average daily net
assets attributable to Class R shares held by such plans.

In addition, redemptions of Class A and Class C shares may be subject to a
contingent deferred sales charge ("CDSC"). A CDSC of 1.00% may be imposed on
redemptions of certain net asset value purchases of Class A shares within 12
months of purchase. Redemptions of Class C shares within 12 months of purchase
are subject to a CDSC of 1.00%, based on the lower of cost or market value of
shares being redeemed. Shares purchased as part of an exchange remain subject
to any CDSC that applied to the original purchase of those shares. There are no
CDSCs for Class K, Class R and Class Y shares. Proceeds from the CDSCs are paid
to the Distributor. For the year ended December 31, 2019, CDSCs in the amount
of $870 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 credit
facility or the limits set for borrowing by the Fund's prospectus and the 1940
Act. The Fund participates in a credit facility that is in the amount of

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



$250 million. Under such facility, depending on the type of loan, interest on
borrowings is payable at the London Interbank Offered Rate ("LIBOR") plus a
credit spread. The Funds also pays an annual commitment fee to participate in a
credit facility. The commitment fee is allocated among participating Funds
based on an allocation schedule set forth in the credit agreement. For the year
ended December 31, 2019, the Fund had no borrowings under the credit facility.

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 41



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, 2019, and the related statement of operations for the year then ended, the
statements of changes in net assets for each of the two years in the period
then ended, the financial highlights for each of the three years in the period
then ended and the related notes (collectively referred to as the "financial
statements"). The financial highlights for the periods ended 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, 2019, the results of its operations for the year then ended, the
changes in its net assets for each of the two years in the period then ended,
and its financial highlights for each of the three years in the period then
ended 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.

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



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, 2019, 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 auditor of one or more Amundi Pioneer investment
companies since 2017.

Boston, Massachusetts
February 26, 2020

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 43



ADDITIONAL INFORMATION (unaudited)

For the year ended December 31, 2019, certain dividends paid by the Fund may be
subject to a maximum tax rate of 20%. The Fund intends to designate up to the
maximum amount of such dividends allowable, as taxed at a maximum rate of 20%.
Complete information will be computed and reported in conjunction with your
2019 Form 1099-DIV.

The qualifying percentage of the Fund's ordinary income dividends for the
purpose of the corporate dividends received deduction was 100%.

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



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 2019 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 2019,
July 2019 and September 2019. 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 2019, 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 2019, 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 2019.

At a meeting held on September 17, 2019, based on their evaluation of the
information provided by APAM and third parties, the Trustees of the Fund,
including the Independent Trustees voting separately, unanimously approved the
renewal of the investment management agreement for another year. In approving
the renewal of the investment management agreement, the Trustees

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 45



considered various factors that they determined were relevant, including the
factors described below. The Trustees did not identify any single factor as the
controlling factor in determining to approve the renewal of the agreement.

Nature, Extent and Quality of Services

The Trustees considered the nature, extent and quality of the services that had
been provided by APAM to the Fund, taking into account the investment objective
and strategy of the Fund. The Trustees also reviewed APAM's investment approach
for the Fund and its research process. The Trustees considered the resources of
APAM and the personnel of APAM who provide investment management services to
the Fund. They also reviewed the amount of non-Fund assets managed by the
portfolio managers of the Fund. They considered the non-investment resources
and personnel of APAM that are involved in APAM's services to the Fund,
including APAM's compliance, risk management, and legal resources and
personnel. The Trustees noted the substantial attention and high priority given
by APAM's senior management to the Pioneer Fund complex.

The Trustees considered that APAM supervises and monitors the performance of
the Fund's service providers and provides the Fund with personnel (including
Fund officers) and other resources that are necessary for the Fund's business
management and operations. The Trustees also considered that, as administrator,
APAM is responsible for the administration of the Fund's business and other
affairs. The Trustees considered the fees paid to APAM for the provision of
administration services.

Based on these considerations, the Trustees concluded that the nature, extent
and quality of services that had been provided by APAM to the Fund were
satisfactory and consistent with the terms of the investment management
agreement.

Performance of the Fund

In considering the Fund's performance, the Trustees regularly review and
discuss throughout the year data prepared by APAM and information comparing the
Fund's performance with the performance of its peer group of funds, as
classified by Morningstar, Inc. (Morningstar), and the performance of the
Fund's benchmark index. They also discuss the Fund's performance with APAM on a
regular basis. The Trustees' regular reviews and discussions were factored into
the Trustees' deliberations concerning the renewal of the investment management
agreement.

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



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 second 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.

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 47



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.

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



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 $1.6
trillion in assets (including the Pioneer Funds). The Trustees considered that
APAM's relationship with Amundi creates potential opportunities for APAM, APIAM
and Amundi that derive from APAM's relationships with the Fund, including
Amundi's ability to market the services of APAM globally. The Trustees noted
that APAM has access to additional research and portfolio management
capabilities as a result of its relationship with Amundi and Amundi's enhanced
global presence that may contribute to an increase in the resources available to
APAM. The Trustees considered that APAM and the Fund receive reciprocal
intangible benefits from the relationship, including mutual brand recognition
and, for the Fund, direct and indirect access to the resources of a large global
asset manager. The Trustees concluded that any such benefits received by APAM as
a result of its relationship with the Fund were reasonable.

Conclusion

After consideration of the factors described above as well as other factors,
the Trustees, including the Independent Trustees, concluded that the investment
management agreement for the Fund, including the fees payable thereunder, was
fair and reasonable and voted to approve the proposed renewal of the investment
management agreement.

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 49



Trustees, Officers and Service Providers

Investment Adviser and Administrator
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

Transfer Agent
DST Asset Manager Solutions, Inc.

Proxy Voting Policies and Procedures of the Fund are available without charge,
upon request, by calling our toll free number (1-800-225-6292). Information
regarding how the Fund voted proxies relating to portfolio securities during
the most recent 12-month period ended June 30 is publicly available to
shareowners at www.amundipioneer.com/us. This information is also available on
the Securities and Exchange Commission's web site at www.sec.gov.

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 45 U.S. registered
investment portfolios for which Amundi Pioneer serves as investment adviser
(the "Pioneer Funds"). The address for all Trustees and all officers of the
Fund is 60 State Street, Boston, Massachusetts 02109.

The Statement of Additional Information of the Fund includes additional
information about the Trustees and is available, without charge, upon request,
by calling 1-800-225-6292.

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



Independent Trustees



Name, Age and Position     Term of Office and                                                           Other Directorships
Held With the Fund         Length of Service              Principal Occupation                          Held by Trustee
------------------------------------------------------------------------------------------------------------------------------------
                                                                                               
Thomas J. Perna (68)       Trustee since 2006.            Private investor (2004 - 2008 and 2013 -      Director, Broadridge
Chairman of the Board      Serves until a successor       present); Chairman (2008 - 2013) and Chief    Financial Solutions, Inc.
and Trustee                trustee is elected or earlier  Executive Officer (2008 - 2012), Quadriserv,  (investor communications
                           retirement or removal.         Inc. (technology products for securities      and securities processing
                                                          lending industry); and Senior Executive Vice  provider for financial
                                                          President, The Bank of New York (financial    services industry) (2009 -
                                                          and securities services) (1986 - 2004)        present); Director,
                                                                                                        Quadriserv, Inc. (2005 -
                                                                                                        2013); and Commissioner,
                                                                                                        New Jersey State Civil
                                                                                                        Service Commission
                                                                                                        (2011 - 2015)
------------------------------------------------------------------------------------------------------------------------------------
John E. Baumgardner,       Trustee since 2019.            Of Counsel (2019 - present), Partner          Chairman, The Lakeville
Jr. (68)                   Serves until a successor       (1983-2018), Sullivan & Cromwell LLP          Journal Company, LLC,
Trustee                    trustee is elected or earlier  (law firm).                                   (privately-held community
                           retirement or removal.                                                       newspaper group)
                                                                                                        (2015-present)
------------------------------------------------------------------------------------------------------------------------------------
Diane Durnin (62)          Trustee since 2019.            Managing Director - Head of Product           None
Trustee                    Serves until a successor       Strategy and Development, BNY Mellon
                           trustee is elected or earlier  Investment Management (2012-2018); Vice
                           retirement or removal.         Chairman - The Dreyfus Corporation
                                                          (2005 - 2018): Executive Vice President
                                                          Head of Product, BNY Mellon Investment
                                                          Management (2007-2012); Executive Director -
                                                          Product Strategy, Mellon Asset Management
                                                          (2005-2007); Executive Vice President Head
                                                          of Products, Marketing and Client Service,
                                                          Dreyfus Corporation (2000-2005); and Senior
                                                          Vice President Strategic Product and
                                                          Business Development, Dreyfus Corporation
                                                          (1994-2000)
------------------------------------------------------------------------------------------------------------------------------------
Benjamin M. Friedman (75)  Trustee since 2008.            William Joseph Maier Professor of Political   Trustee, Mellon
Trustee                    Serves until a successor       Economy, Harvard University (1972 - present)  Institutional Funds
                           trustee is elected or earlier                                                Investment Trust and Mellon
                           retirement or removal.                                                       Institutional Funds Master
                                                                                                        Portfolio (oversaw 17
                                                                                                        portfolios in fund complex)
                                                                                                        (1989 - 2008)
------------------------------------------------------------------------------------------------------------------------------------

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 51



Independent Trustees (continued)



Name, Age and Position     Term of Office and                                                           Other Directorships
Held With the Fund         Length of Service              Principal Occupation                          Held by Trustee
------------------------------------------------------------------------------------------------------------------------------------
                                                                                               
Lorraine H. Monchak (62)   Trustee since 2017.            Chief Investment Officer, 1199 SEIU Funds     None
Trustee                    (Advisory Trustee from         (healthcare workers union pension funds)
                           2014 - 2017). Serves until     (2001 - present); Vice President -
                           a successor trustee is         International Investments Group, American
                           elected or earlier retirement  International Group, Inc. (insurance
                           or removal.                    company) (1993 - 2001); Vice President -
                                                          Corporate Finance and Treasury Group,
                                                          Citibank, N.A. (1980 - 1986 and 1990 -
                                                          1993); Vice President - Asset/Liability
                                                          Management Group, Federal Farm Funding
                                                          Corporation (government-sponsored issuer of
                                                          debt securities) (1988 - 1990); Mortgage
                                                          Strategies Group, Shearson Lehman Hutton,
                                                          Inc. (investment bank) (1987 - 1988); and
                                                          Mortgage Strategies Group, Drexel Burnham
                                                          Lambert, Ltd. (investment bank)
                                                          (1986 - 1987)
------------------------------------------------------------------------------------------------------------------------------------
Marguerite A. Piret (71)   Trustee since 1982.            President and Chief Executive Officer,        Director of New America High
Trustee                    Serves until a successor       Metric Financial Inc. (formerly known as      Income Fund, Inc.
                           trustee is elected or earlier  Newbury Piret Company) (investment banking    (closed-end investment
                           retirement or removal.         firm) (1981 - present)                        company) (2004 - present);
                                                                                                        and Member, Board of
                                                                                                        Governors, Investment
                                                                                                        Company Institute
                                                                                                        (2000 - 2006)
------------------------------------------------------------------------------------------------------------------------------------
Fred J. Ricciardi (72)     Trustee since 2014.            Consultant (investment company services)      None
Trustee                    Serves until a successor       (2012 - present); Executive Vice President,
                           trustee is elected or earlier  BNY Mellon (financial and investment company
                           retirement or removal.         services) (1969 - 2012); Director, BNY
                                                          International Financing Corp. (financial
                                                          services) (2002 - 2012); 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)
------------------------------------------------------------------------------------------------------------------------------------


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



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 (57)*        Trustee since 2017.            Director, CEO and President of Amundi         None
Trustee, President and     Serves until a successor       Pioneer Asset Management USA, Inc. (since
Chief Executive Officer    trustee is elected or earlier  September 2014); Director, CEO and President
                           retirement or removal          of Amundi Pioneer Asset Management, Inc.
                                                          (since September 2014); Director, CEO and
                                                          President of Amundi Pioneer Distributor,
                                                          Inc. (since September 2014); Director, CEO
                                                          and President of Amundi Pioneer
                                                          Institutional Asset Management, Inc. (since
                                                          September 2014); Chair, Amundi Pioneer Asset
                                                          Management USA, Inc., Amundi Pioneer
                                                          Distributor, Inc. and Amundi Pioneer
                                                          Institutional Asset Management, Inc.
                                                          (September 2014 - 2018); Managing Director,
                                                          Morgan Stanley Investment Management
                                                          (2010 - 2013); Director of Institutional
                                                          Business, CEO of International, Eaton Vance
                                                          Management (2005 - 2010); and Director of
                                                          Amundi USA, Inc. (since 2017)
------------------------------------------------------------------------------------------------------------------------------------
Kenneth J. Taubes (61)*    Trustee since 2014.            Director and Executive Vice President (since  None
Trustee                    Serves until a successor       2008) and Chief Investment Officer, U.S.
                           trustee is elected or earlier  (since 2010) of Amundi Pioneer Asset
                           retirement or removal          Management USA, Inc.; Director and
                                                          Executive Vice President and Chief
                                                          Investment Officer, U.S. of Amundi Pioneer
                                                          (since 2008); Executive Vice President and
                                                          Chief Investment Officer, U.S. of Amundi
                                                          Pioneer Institutional Asset Management, Inc.
                                                          (since 2009); Portfolio Manager of Amundi
                                                          Pioneer (since 1999); and Director of Amundi
                                                          USA, Inc. (since 2017)
------------------------------------------------------------------------------------------------------------------------------------



* Ms. Jones and Mr. Taubes are Interested Trustees because they are officers or
directors of the Fund's investment adviser and certain of its affiliates.

                          Pioneer Core Equity Fund | Annual Report | 12/31/19 53



Fund Officers



Name, Age and Position     Term of Office and                                                          Other Directorships
Held With the Fund         Length of Service              Principal Occupation                          Held by Officer
------------------------------------------------------------------------------------------------------------------------------------
                                                                                               
Christopher J. Kelley (55) Since 2003. Serves at the      Vice President and Associate General Counsel  None
Secretary and Chief        discretion of the Board        of Amundi Pioneer since January 2008;
Legal Officer                                             Secretary and 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 (58)     Since 2010. Serves at the      Fund Governance Director of Amundi Pioneer    None
Assistant Secretary        discretion of the Board        since December 2006 and Assistant Secretary
                                                          of all the 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 (57)          Since 2010. Serves at the      Assistant General Counsel of Amundi Pioneer   None
Assistant Secretary        discretion of the Board        since May 2013 and Assistant Secretary of
                                                          all the Pioneer Funds since June 2010; and
                                                          Counsel of Amundi Pioneer from June 2007 to
                                                          May 2013
------------------------------------------------------------------------------------------------------------------------------------
Mark E. Bradley (60)       Since 2008. Serves at the      Vice President - Fund Treasury of Amundi      None
Treasurer and Chief        discretion of the Board        Pioneer; Treasurer of all of the Pioneer
Financial and                                             Funds since March 2008; Deputy Treasurer of
Accounting Officer                                        Amundi 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 (54)      Since 2000. Serves at the      Director - Fund Treasury of Amundi Pioneer;   None
Assistant Treasurer        discretion of the Board        and Assistant Treasurer of all of the
                                                          Pioneer Funds
------------------------------------------------------------------------------------------------------------------------------------
Gary Sullivan (61)         Since 2002. Serves at the      Senior Manager - Fund Treasury of Amundi      None
Assistant Treasurer        discretion of the Board        Pioneer; and Assistant Treasurer of all of
                                                          the Pioneer Funds
------------------------------------------------------------------------------------------------------------------------------------


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





Name, Age and Position     Term of Office and                                                           Other Directorships
Held With the Fund         Length of Service              Principal Occupation                          Held by Officer
------------------------------------------------------------------------------------------------------------------------------------
                                                                                               
John Malone (48)           Since 2018. Serves at the      Managing Director, Chief Compliance Officer   None
Chief Compliance Officer   discretion of the Board        of Amundi Pioneer Asset Management; Amundi
                                                          Pioneer 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 (48)       Since 2006. Serves at the      Vice President - Amundi Pioneer Asset         None
Anti-Money Laundering      discretion of the Board        Management; and Anti-Money Laundering
Officer                                                   Officer of all the Pioneer Funds since 2006
------------------------------------------------------------------------------------------------------------------------------------


                          Pioneer Core Equity Fund | Annual Report | 12/31/19 55




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



How to Contact Amundi Pioneer

We are pleased to offer a variety of convenient ways for you to contact us for
assistance or information.

Call us for:
--------------------------------------------------------------------------------
Account Information, including existing accounts,
new accounts, prospectuses, applications
and service forms                                                 1-800-225-6292

FactFoneSM for automated fund yields, prices,
account information and transactions                              1-800-225-4321

Retirement plans information                                      1-800-622-0176

Write to us:
--------------------------------------------------------------------------------
Amundi Pioneer
P.O. Box 219427
Kansas City, MO 64121-9427

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

Our internet e-mail address                us.askamundipioneer@amundipioneer.com
(for general questions about Amundi Pioneer only)

Visit our web site: www.amundipioneer.com/us

This report must be preceded or accompanied by a prospectus.

The Fund files a complete schedule of portfolio holdings with the Securities
and Exchange Commission for the first and third quarters of each fiscal year as
an exhibit to its reports on Form N-PORT. Shareholders may view the filed Form
N-PORT by visiting the Commission's web site at https://www.sec.gov.



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

Amundi Pioneer Asset Management, Inc.
60 State Street
Boston, MA 02109
www.amundipioneer.com/us

Securities offered through Amundi Pioneer Distributor, Inc.
60 State Street, Boston, MA 02109
Underwriter of Pioneer Mutual Funds, Member SIPC
[C] 2020 Amundi Pioneer Asset Management 18630-14-0220



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, 2019 and $25,500
for the year ended December 31, 2018.


(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.

Audit-Related Fees
There were no audit-related services in 2019 or 2018.


(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, 2019 and $8,028
for the year ended December 31, 2018.


(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 2019 or 2018.

(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 2019 and 2018, 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, 2019 and $8,028 for the year
ended December 31, 2018.


(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.

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 3, 2020


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 3, 2020


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

Date March 3, 2020

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