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

                                   FORM N-CSR

                   CERTIFIED SHAREHOLDER REPORT OF REGISTERED
                        MANAGEMENT INVESTMENT COMPANIES



		Investment Company Act file number 811-01835

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


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


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


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


Date of fiscal year end:  December 31


Date of reporting period:  January 1, 2019 through June 30, 2019


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

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


ITEM 1. REPORTS TO STOCKHOLDERS.



                                  Pioneer Core
                                  Equity Fund

--------------------------------------------------------------------------------
                                  Semiannual Report | June 30, 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

Trustees, Officers and Service Providers                                     42


                        Pioneer Core Equity Fund | Semiannual Report | 6/30/19 1



President's Letter

Since 1928, active portfolio management based on in-depth, fundamental
research, has been the foundation of Amundi Pioneer's investment approach. We
believe an active management investment strategy is a prudent approach to
investing, especially during periods of market volatility, which can result
from any number of risk factors, including slow U.S. economic growth, rising
interest rates, and geopolitical factors. Of course, in today's global economy,
risk factors extend well beyond U.S. borders. In fact, it's not unusual for
political and economic issues on the international front to cause or contribute
to volatility in U.S. markets.

At Amundi Pioneer, each security under consideration is researched by our team
of experienced investment professionals, who communicate directly with the
management teams of those companies. At the end of this research process, if we
have conviction in a company's business model and management team, and regard
the security as a potentially solid investment opportunity, an Amundi Pioneer
portfolio manager makes an active decision to invest in that security. The
portfolio resulting from these decisions represents an expression of his or her
convictions, and strives to balance overall risk and return opportunity.

As an example, the Standard & Poor's 500 Index -- the predominant benchmark for
many U.S. Large-Cap Core Equity funds -- has 500 stocks. An Amundi Pioneer
portfolio manager chooses to invest in only those companies that he or she
believes can offer the most attractive opportunities to pursue the fund's
investment objective, thus potentially benefiting the fund's shareowners. This
process results in a portfolio that does not own all 500 stocks, but a much
narrower universe.

The same active decision to invest in a company is also applied when we decide
to sell a security, either due to changing fundamentals, valuation concerns, or
market risks. We apply this active decision-making across all of our equity,
fixed-income, and global portfolios.

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

2 Pioneer Core Equity Fund | Semiannual Report | 6/30/19



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

Sincerely,

/s/ Lisa M. Jones

Lisa M. Jones
Head of the Americas, President and CEO of U.S.
Amundi Pioneer Asset Management USA, Inc.
June 30, 2019

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

                        Pioneer Core Equity Fund | Semiannual Report | 6/30/19 3



Portfolio Management Discussion | 6/30/19

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 six-month period ended June 30, 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 six-month period ended June 30, 2019?

A     Pioneer Core Equity Fund's Class A shares returned 18.77% at net asset
      value during the six-month period ended June 30, 2019, while the Fund's
      benchmark, the Standard & Poor's 500 Index (the S&P 500), returned 18.54%.
      During the same period, the average return of the 1,447 mutual funds in
      Morningstar's Large Blend Funds category was 17.21%.

Q     How would you describe the environment for the U.S. stock market in the
      first six months of 2019?

A     U.S. equities staged a strong rally during the six-month period. In fact,
      the Fund's benchmark, the S&P 500, registered its best performance for the
      first half of a calendar year since 1997, returning more than 18.5% from
      January 1st through June 30th.

      Heading into the six-month period, equity markets faced a potentially
      challenging combination of slowing global economic growth, rising tariffs
      on both U.S. and Chinese goods due to ongoing trade disputes between the
      two countries, and uncertainty about the outlook for corporate profits.
      However, a shift in U.S. Federal Reserve (Fed) interest-rate policy, from
      tightening throughout 2018 to potentially easing in 2019, far outweighed
      the other concerns and spurred a market rally.

      After raising interest rates four times in 2018, the Fed adopted an
      increasingly dovish tone on monetary policy as the six-month period
      progressed, fueling expectations that it may reverse course from interest-
      rate hikes and actually cut rates several times by mid-2020. The
      expectations represented a stark contrast to the market consensus of late
      2018, when investors were anticipating continued Fed interest-rate

4 Pioneer Core Equity Fund | Semiannual Report | 6/30/19



      increases through 2019. The 180-degree turn in Fed monetary policy
      provided a firm underpinning for the equity market, and more than overcame
      the potential headwinds from the other factors mentioned earlier.

      Over the first half of 2019, equity markets were positive in every month
      except for May, when concerns about trade disputes and tariffs reached
      their apex. Growth stocks outperformed value stocks during the period, as
      investors were attracted to companies with the ability to generate organic
      earnings growth independent of broader economic trends. The Russell 1000
      Growth Index gained 21.49% in the first half of the year, outpacing the
      16.24% return of the Russell 1000 Value Index.

      Within the S&P 500, all sectors posted positive returns for the six-month
      period, with information technology leading the way. Health care and
      energy were the S&P 500's weakest-performing sectors over the period,
      though the returns of those sectors were also solidly positive.

Q     What were the most important factors driving the Fund's benchmark-relative
      performance during the six-month period ended June 30, 2019?

A     Stock selection was the primary driver of the Fund's positive benchmark-
      relative returns during the period, led by outperformance in the health
      care, information technology, and financials sectors. Conversely, the
      Fund's holdings in communications services, energy, and industrials lagged
      the performance of the corresponding benchmark sectors. Sector allocations
      were also a positive for the Fund versus the S&P 500, highlighted by the
      portfolio's average underweight to the weaker-performing health care
      sector, and an overweight in consumer discretionary, which was a strong
      performer over the six months.

      With regard to individual stocks, strong security selection results in
      health care stemmed in part from a portfolio position in Laboratory
      Corporation of America, which bounced back from a weak 2018 and
      contributed positively to the Fund's benchmark-relative performance for
      the six-month period. Laboratory Corporation, which we believe is a stable
      and well- managed company, overcame some short-term difficulties, which
      led to renewed investor interest during the period. Another positive
      contributor to the Fund's benchmark-relative returns were shares of
      Zoetis, a producer of medicine and vaccinations for animals, including
      house pets and livestock. The stock gained ground during the period after
      the company posted robust earnings results and increased its market share.

                        Pioneer Core Equity Fund | Semiannual Report | 6/30/19 5



      In information technology, the Fund's outperformance of the S&P 500
      derived primarily from positions in semiconductor stocks, many of which
      surged off their late-2018 lows, including Advanced Micro Devices, Micron
      Technology, and Lam Research.

      In financials, the Fund's relative returns benefited from the
      outperformance of Progressive, which continued to evolve as a
      best-in-breed company in the insurance industry. A position in Discover
      Financial Services, one of the largest credit card issuers in the world,
      was another leading contributor to the Fund's benchmark-relative results
      over the six-month period. We initially invested in the stock when the
      share price was discounting a deterioration in credit quality that we
      thought unlikely to materialize at a time of low unemployment and rising
      wages. We chose to sell the Fund's shares in Discover during the second
      calendar quarter of 2019, after they reached valuations we no longer saw
      as compelling.

      In addition, although the Fund lagged the benchmark's return within
      industrials, the sector was also home to United Rentals, one of the top
      contributors to the Fund's overall performance for the six-month period.

Q     What aspects of the Fund's positioning detracted from benchmark-relative
      performance during the six-month period ended June 30, 2019?

A     Lack of portfolio exposure to social-media leader Facebook was the key
      detractor from the Fund's benchmark-relative performance in both the
      communication services sector, and overall. During the period, investors
      seemed willing to look beyond the possibility of regulatory or user
      backlash against Facebook resulting from privacy issues and
      anti-competitive behavior. Instead, the market focused on the possible
      upside from growth in the company's Instagram platform, and potential
      future revenues from Facebook's recently announced cryptocurrency
      development. We view other internet media stocks, including Alphabet, as
      more attractive than Facebook, given that such companies have what we
      believe to be more viable business models as well as greater potential to
      create value over the long term.

      In energy, a key detractor from the Fund's benchmark-relative returns
      during the period was a position in Halliburton, a large oil-and-gas
      equipment & services company. We based our investment thesis for
      Halliburton on the company's strong competitive position in the U.S.
      market, but some previously low-end competitors proceeded to improve their
      abilities to offer higher-value solutions. The resulting decline in
      Halliburton's competitive advantage, combined with weaker-than-expected
      spending by its target customer base, prompted us to sell the Fund's
      position. Also in energy, an investment in the high-quality

6 Pioneer Core Equity Fund | Semiannual Report | 6/30/19



      exploration-and-production company EOG Resources detracted from the Fund's
      relative performance, but we chose to maintain the position based on our
      positive view regarding EOG's longer-term potential.

      Finally, in industrials, a portfolio position in FedEx was the primary
      reason for the Fund's performance shortfall versus the S&P 500 within the
      sector. FedEx has had difficulties integrating its acquisition of the
      European company DHL, while also disappointing investors with a management
      turnover as well as rising capital expenditures. Believing our original
      investment thesis was no longer valid, we exited the Fund's position.

Q     Did the Fund own any derivative securities during the six-month period
      ended June 30, 2019? If so, did the investments have a material impact on
      benchmark-relative results?

A     No. The Fund did not own any derivatives during the reporting period.

Q     How would you characterize the Fund's overall positioning during the
      six-month period ended June 30, 2019, and could you discuss any changes
      you made to the portfolio?

A     As the second calendar quarter of 2019 progressed (April through June), we
      reduced the portfolio's weighting in cyclical (economically sensitive)
      stocks and rotated into stocks of companies with either more defensive
      characteristics, or that have featured growth trends largely independent
      of economic developments and conditions. Given the elevated risks with
      respect to both economic growth and the equity markets, we believed
      attractively valued stocks of high-quality companies with secular (versus
      cyclical) growth potential would experience stronger investor demand.

      Accordingly, we lowered the Fund's exposure to companies that may be
      vulnerable to weaker-than-expected capital expenditures, and where we
      thought stock valuations had gotten ahead of themselves. As part of the
      shift, we reduced the Fund's weightings in the semiconductor, capital
      goods, and automotive industries. At the individual company level, we
      reduced the size of the Fund's positions in Micron Technology and United
      Rentals, and exited the position in Advanced Micro Devices.

      We rotated the proceeds of those sales into areas of the market where we
      saw robust fundamentals, more compelling valuations, and lower economic
      sensitivity. We increased the Fund's weighting in health care,
      particularly among large-cap pharmaceuticals and managed-care companies.
      In making the move, we purposely avoided owning stocks of companies in
      traditionally defensive sectors such as consumer staples and utilities. We
      think many stocks in those areas are very expensive, and therefore offer
      little upside. We also feel that investors may not fully appreciate the
      higher risks involved with investing in those sectors.

                        Pioneer Core Equity Fund | Semiannual Report | 6/30/19 7



      We continued to hold a sizable portfolio weighting in the information
      technology sector, with a preference for companies leveraged to important
      growth trends such as cloud computing, software-as-a-service, and
      digitization. Although tech stocks have done well this year, we believe
      many remain undervalued relative to the companies' potential growth rates.
      We also remained bullish on the U.S. consumer sector, especially stocks of
      companies that we believe may benefit from the home repair and remodeling
      theme, such as Home Depot.

      In financials, we believe that scale, brand, and technological
      capabilities are now driving the banking industry to a larger and larger
      degree, and that belief forms the basis for the Fund's holdings of Bank of
      America and JPMorgan Chase. We also like Progressive, the insurer we
      discussed earlier, as the company appears to have separated itself from
      its competitors through its durable brand and ability to use technology to
      help manage risk.

Q     Do you have any closing thoughts for investors?

A     While equities registered solid, even spectacular returns in the first
      half of the calendar year, we think weaker global economic growth trends
      may feed through into slower corporate earnings growth over the next few
      quarters. The Fed has communicated its willingness to cut interest rates,
      which could help stabilize economic activity and give the market greater
      confidence about the prospects for a "soft landing" of the domestic
      economy. However, if the Fed fails to act quickly enough -- or if the
      uncertainty surrounding trade disputes persists for longer than expected
      -- the resulting risks for the market could be high.

      In our view, such circumstances may prompt investors to gravitate toward
      attractively valued stocks of higher quality and more defensive companies
      with robust underlying business models, high profitability, below-average
      debt, and secular growth opportunities. We believe our emphasis on holding
      shares of those types of companies in the Fund's portfolio is well suited
      to this environment.

8 Pioneer Core Equity Fund | Semiannual Report | 6/30/19



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 | Semiannual Report | 6/30/19 9



Portfolio Summary | 6/30/19

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



                                                                        
Information Technology                                                     21.0%
Financials                                                                 17.0%
Health Care                                                                16.7%
Consumer Discretionary                                                     14.4%
Communication Services                                                      6.8%
Industrials                                                                 5.9%
Real Estate                                                                 4.3%
Energy                                                                      4.1%
Consumer Staples                                                            3.9%
Government                                                                  3.1%
Materials                                                                   2.3%
Utilities                                                                   0.5%


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



                                                                        
 1. Microsoft Corp.                                                        5.95%
--------------------------------------------------------------------------------
 2. Amazon.com, Inc.                                                       5.62
--------------------------------------------------------------------------------
 3. JPMorgan Chase & Co.                                                   4.81
--------------------------------------------------------------------------------
 4. Home Depot, Inc.                                                       4.11
--------------------------------------------------------------------------------
 5. Alphabet, Inc.                                                         3.84
--------------------------------------------------------------------------------
 6. Humana, Inc.                                                           3.00
--------------------------------------------------------------------------------
 7. Progressive Corp.                                                      3.00
--------------------------------------------------------------------------------
 8. Merck & Co., Inc.                                                      2.92
--------------------------------------------------------------------------------
 9. EOG Resources, Inc.                                                    2.91
--------------------------------------------------------------------------------
10. Bank of America Corp.                                                  2.65
--------------------------------------------------------------------------------


*     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 | Semiannual Report | 6/30/19



Prices and Distributions | 6/30/19

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



--------------------------------------------------------------------------------
          Class                    6/30/19                   12/31/18
--------------------------------------------------------------------------------
                                                        
            A                       $18.92                    $15.93
--------------------------------------------------------------------------------
            C                       $16.35                    $13.82
--------------------------------------------------------------------------------
            K                       $18.93                    $15.91
--------------------------------------------------------------------------------
            R                       $18.85                    $15.90
--------------------------------------------------------------------------------
            Y                       $19.20                    $16.14
--------------------------------------------------------------------------------


Distributions per Share: 1/1/19 - 6/30/19
--------------------------------------------------------------------------------



--------------------------------------------------------------------------------
                      Net Investment          Short-Term          Long-Term
          Class          Income              Capital Gains       Capital Gains
--------------------------------------------------------------------------------
                                                            
            A              $ --                  $ --                $ --
--------------------------------------------------------------------------------
            C              $ --                  $ --                $ --
--------------------------------------------------------------------------------
            K              $ --                  $ --                $ --
--------------------------------------------------------------------------------
            R              $ --                  $ --                $ --
--------------------------------------------------------------------------------
            Y              $ --                  $ --                $ --
--------------------------------------------------------------------------------


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.

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/19 11



Performance Update | 6/30/19                                      Class A Shares

Investment Returns
--------------------------------------------------------------------------------
The mountain chart on the right shows the change in value of a $10,000
investment made in Class A shares of Pioneer 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 June 30, 2019)
------------------------------------------------------
                  Net          Public
                  Asset        Offering       S&P
                  Value        Price          500
Period            (NAV)        (POP)          Index
------------------------------------------------------
                                     
10 years          13.10%       12.44%         14.70%
5 years            8.61         7.33          10.71
1 year             5.87        -0.22          10.42
------------------------------------------------------


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
                                                  
6/09                                $ 9,425             $10,000
6/10                                $10,628             $11,443
6/11                                $14,136             $14,955
6/12                                $14,713             $15,770
6/13                                $17,264             $19,018
6/14                                $21,370             $23,698
6/15                                $22,465             $25,457
6/16                                $21,858             $26,473
6/17                                $26,474             $31,211
6/18                                $30,498             $35,698
6/19                                $32,289             $39,416


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 | Semiannual Report | 6/30/19



Performance Update | 6/30/19                                      Class C Shares

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



Average Annual Total Returns
(As of June 30, 2019)
------------------------------------------------------
                                               S&P
                   If           If             500
Period             Held         Redeemed       Index
------------------------------------------------------
                                      
10 years           12.12%        12.12%        14.70%
5 years             7.72          7.72         10.71
1 year              5.05          5.05         10.42
------------------------------------------------------


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
                                                  
6/09                                $10,000             $10,000
6/10                                $11,173             $11,443
6/11                                $14,716             $14,955
6/12                                $15,182             $15,770
6/13                                $17,638             $19,018
6/14                                $21,641             $23,698
6/15                                $22,556             $25,457
6/16                                $21,781             $26,473
6/17                                $26,158             $31,211
6/18                                $29,884             $35,698
6/19                                $31,394             $39,416


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 | Semiannual Report | 6/30/19 13



Performance Update | 6/30/19                                      Class K Shares

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



Average Annual Total Returns
(As of June 30, 2019)
------------------------------------------------------
                               Net
                               Asset          S&P
                               Value          500
Period                         (NAV)          Index
------------------------------------------------------
                                        
10 years                       13.15%         14.70%
5 years                         8.70          10.71
1 year                          6.26          10.42
------------------------------------------------------


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
                                                  
6/09                                $ 5,000,000         $ 5,000,000
6/10                                $ 5,638,234         $ 5,721,488
6/11                                $ 7,499,371         $ 7,477,511
6/12                                $ 7,805,054         $ 7,884,886
6/13                                $ 9,158,620         $ 9,508,949
6/14                                $11,336,645         $11,849,007
6/15                                $11,917,993         $12,728,534
6/16                                $11,595,838         $13,236,737
6/17                                $14,044,540         $15,605,596
6/18                                $16,187,162         $17,848,762
6/19                                $17,201,284         $19,708,142


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 more recent expense ratios.

14 Pioneer Core Equity Fund | Semiannual Report | 6/30/19



Performance Update | 6/30/19                                      Class R Shares

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



Average Annual Total Returns
(As of June 30, 2019)
------------------------------------------------------
                              Net
                              Asset           S&P
                              Value           500
Period                        (NAV)           Index
------------------------------------------------------
                                        
10 years                      13.08%          14.70%
5 years                        8.55           10.71
1 year                         5.61           10.42
------------------------------------------------------


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
                                                  
6/09                                $10,000             $10,000
6/10                                $11,276             $11,443
6/11                                $14,999             $14,955
6/12                                $15,610             $15,770
6/13                                $18,317             $19,018
6/14                                $22,673             $23,698
6/15                                $23,836             $25,457
6/16                                $23,192             $26,473
6/17                                $28,089             $31,211
6/18                                $32,359             $35,698
6/19                                $34,173             $39,416


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 more recent expense ratios.

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/19 15



Performance Update | 6/30/19                                      Class Y Shares

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



Average Annual Total Returns
(As of June 30, 2019)
------------------------------------------------------
                               Net
                               Asset           S&P
                               Value           500
Period                         (NAV)           Index
------------------------------------------------------
                                         
10 years                       13.40%          14.70%
5 years                         8.91           10.71
1 year                          6.11           10.42
------------------------------------------------------


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
                                                  
6/09                                $ 5,000,000         $ 5,000,000
6/10                                $ 5,651,032         $ 5,721,488
6/11                                $ 7,532,567         $ 7,477,511
6/12                                $ 7,855,260         $ 7,884,886
6/13                                $ 9,240,696         $ 9,508,949
6/14                                $11,474,833         $11,849,007
6/15                                $12,101,430         $12,728,534
6/16                                $11,816,188         $13,236,737
6/17                                $14,344,898         $15,605,596
6/18                                $16,570,915         $17,848,762
6/19                                $17,583,565         $19,708,142


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 | Semiannual Report | 6/30/19



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 January 1, 2019, through June 30, 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 1/1/19
------------------------------------------------------------------------------------------------
Ending Account Value             $1,187.70    $1,183.10    $1,189.80    $1,185.50    $1,189.60
on 6/30/19
------------------------------------------------------------------------------------------------
Expenses Paid                        $4.88        $9.31        $3.04        $6.88        $3.58
During Period*
------------------------------------------------------------------------------------------------


*     Expenses are equal to the Fund's annualized expense ratio of 0.90%, 1.72%,
      0.56%, 1.27%, 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 181/365 (to reflect the one-half year period).


                       Pioneer Core Equity Fund | Semiannual Report | 6/30/19 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 January 1, 2019, through June 30, 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 1/1/19
------------------------------------------------------------------------------------------------
Ending Account Value             $1,020.33    $1,016.27    $1,022.02    $1,018.50    $1,021.52
on 6/30/19
------------------------------------------------------------------------------------------------
Expenses Paid                        $4.51        $8.60        $2.81        $6.36        $3.31
During Period*
------------------------------------------------------------------------------------------------


*     Expenses are equal to the Fund's annualized expense ratio of 0.90%, 1.72%,
      0.56%, 1.27%, 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 181/365 (to reflect the one-half year period).

18 Pioneer Core Equity Fund | Semiannual Report | 6/30/19



Schedule of Investments | 6/30/19 (unaudited)



--------------------------------------------------------------------------------------------------------------
Shares                                                                                          Value
--------------------------------------------------------------------------------------------------------------
                                                                                          
                    UNAFFILIATED ISSUERS -- 98.1%
                    COMMON STOCKS -- 95.0% of Net Assets
                    Aerospace & Defense -- 1.2%
   109,649          Raytheon Co.                                                                $   19,065,768
                                                                                                --------------
                    Total Aerospace & Defense                                                   $   19,065,768
--------------------------------------------------------------------------------------------------------------
                    Auto Components -- 2.1%
   227,358          Aptiv PLC                                                                   $   18,377,347
   402,191          BorgWarner, Inc.                                                                16,883,978
                                                                                                --------------
                    Total Auto Components                                                       $   35,261,325
--------------------------------------------------------------------------------------------------------------
                    Banks -- 8.4%
 1,450,639          Bank of America Corp.                                                       $   42,068,531
   683,577          JPMorgan Chase & Co.                                                            76,423,909
    76,757(a)       SVB Financial Group                                                             17,238,855
                                                                                                --------------
                    Total Banks                                                                 $  135,731,295
--------------------------------------------------------------------------------------------------------------
                    Beverages -- 1.9%
   235,166          PepsiCo., Inc.                                                              $   30,837,317
                                                                                                --------------
                    Total Beverages                                                             $   30,837,317
--------------------------------------------------------------------------------------------------------------
                    Capital Markets -- 3.0%
    36,176          BlackRock, Inc.                                                             $   16,977,397
   221,840          Intercontinental Exchange, Inc.                                                 19,064,930
   310,872          Morgan Stanley                                                                  13,619,302
                                                                                                --------------
                    Total Capital Markets                                                       $   49,661,629
--------------------------------------------------------------------------------------------------------------
                    Chemicals -- 1.5%
   334,701          Dow, Inc.                                                                   $   16,504,106
    41,989          Ecolab, Inc.                                                                     8,290,308
                                                                                                --------------
                    Total Chemicals                                                             $   24,794,414
--------------------------------------------------------------------------------------------------------------
                    Communications Equipment -- 0.6%
    36,856(a)       Arista Networks, Inc.                                                       $    9,568,555
                                                                                                --------------
                    Total Communications Equipment                                              $    9,568,555
--------------------------------------------------------------------------------------------------------------
                    Containers & Packaging -- 0.7%
   169,048          Ball Corp.                                                                  $   11,831,670
                                                                                                --------------
                    Total Containers & Packaging                                                $   11,831,670
--------------------------------------------------------------------------------------------------------------
                    Diversified Telecommunication Services -- 2.1%
 1,013,892          AT&T, Inc.                                                                  $   33,975,521
                                                                                                --------------
                    Total Diversified Telecommunication Services                                $   33,975,521
--------------------------------------------------------------------------------------------------------------
                    Electric Utilities -- 0.5%
    83,292          American Electric Power Co., Inc.                                           $    7,330,529
                                                                                                --------------
                    Total Electric Utilities                                                    $    7,330,529
--------------------------------------------------------------------------------------------------------------


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

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/19 19



Schedule of Investments | 6/30/19 (unaudited) (continued)



--------------------------------------------------------------------------------------------------------------
Shares                                                                                          Value
--------------------------------------------------------------------------------------------------------------
                                                                                          
                    Electronic Equipment, Instruments & Components -- 2.1%
   186,409          Amphenol Corp.                                                              $   17,884,079
   139,882          CDW Corp.                                                                       15,526,902
                                                                                                --------------
                    Total Electronic Equipment, Instruments & Components                        $   33,410,981
--------------------------------------------------------------------------------------------------------------
                    Entertainment -- 0.8%
    71,337(a)       Live Nation Entertainment, Inc.                                             $    4,726,076
   288,674          Viacom, Inc., Class B                                                            8,622,692
                                                                                                --------------
                    Total Entertainment                                                         $   13,348,768
--------------------------------------------------------------------------------------------------------------
                    Equity Real Estate Investment Trusts (REITs) -- 4.3%
   147,633          Digital Realty Trust, Inc.                                                  $   17,389,691
    58,544          Essex Property Trust, Inc.                                                      17,090,750
    97,790          Liberty Property Trust                                                           4,893,412
   145,628          Prologis, Inc.                                                                  11,664,803
   113,744          Simon Property Group, Inc.                                                      18,171,741
                                                                                                --------------
                    Total Equity Real Estate Investment Trusts (REITs)                          $   69,210,397
--------------------------------------------------------------------------------------------------------------
                    Food & Staples Retailing -- 1.6%
    67,551          Costco Wholesale Corp.                                                      $   17,851,027
   162,099          Walgreens Boots Alliance, Inc.                                                   8,861,952
                                                                                                --------------
                    Total Food & Staples Retailing                                              $   26,712,979
--------------------------------------------------------------------------------------------------------------
                    Health Care Equipment & Supplies -- 2.9%
    61,253(a)       ABIOMED, Inc.                                                               $   15,955,794
    30,534          Cooper Cos., Inc.                                                               10,286,599
   164,048          ResMed, Inc.                                                                    20,018,777
                                                                                                --------------
                    Total Health Care Equipment & Supplies                                      $   46,261,170
--------------------------------------------------------------------------------------------------------------
                    Health Care Providers & Services -- 5.6%
   179,465          Humana, Inc.                                                                $   47,612,065
   109,719(a)       Laboratory Corp. of America Holdings                                            18,970,415
    96,388          UnitedHealth Group, Inc.                                                        23,519,636
                                                                                                --------------
                    Total Health Care Providers & Services                                      $   90,102,116
--------------------------------------------------------------------------------------------------------------
                    Household Products -- 0.3%
    38,904          Procter & Gamble Co.                                                        $    4,265,824
                                                                                                --------------
                    Total Household Products                                                    $    4,265,824
--------------------------------------------------------------------------------------------------------------
                    Insurance -- 5.3%
   356,620          American International Group, Inc.                                          $   19,000,714
   191,044          Marsh & McLennan Cos., Inc.                                                     19,056,639
   595,376          Progressive Corp.                                                               47,588,404
                                                                                                --------------
                    Total Insurance                                                             $   85,645,757
--------------------------------------------------------------------------------------------------------------
                    Interactive Media & Services -- 3.8%
    56,356(a)       Alphabet, Inc.                                                              $   61,022,277
                                                                                                --------------
                    Total Interactive Media & Services                                          $   61,022,277
--------------------------------------------------------------------------------------------------------------


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

20 Pioneer Core Equity Fund | Semiannual Report | 6/30/19





--------------------------------------------------------------------------------------------------------------
Shares                                                                                          Value
--------------------------------------------------------------------------------------------------------------
                                                                                          
                    Internet & Direct Marketing Retail -- 6.4%
    47,155(a)       Amazon.com, Inc.                                                            $   89,294,123
     7,451(a)       Booking Holdings, Inc.                                                          13,968,464
                                                                                                --------------
                    Total Internet & Direct Marketing Retail                                    $  103,262,587
--------------------------------------------------------------------------------------------------------------
                    IT Services -- 5.2%
   142,849          Accenture PLC                                                               $   26,394,210
   291,338          Cognizant Technology Solutions Corp.                                            18,467,916
   222,577          Visa, Inc.                                                                      38,628,238
                                                                                                --------------
                    Total IT Services                                                           $   83,490,364
--------------------------------------------------------------------------------------------------------------
                    Life Sciences Tools & Services -- 0.4%
     7,996(a)       Mettler-Toledo International, Inc.                                          $    6,716,640
                                                                                                --------------
                    Total Life Sciences Tools & Services                                        $    6,716,640
--------------------------------------------------------------------------------------------------------------
                    Machinery -- 2.0%
   122,830          Stanley Black & Decker, Inc.                                                $   17,762,447
   174,627          Xylem, Inc.                                                                     14,605,802
                                                                                                --------------
                    Total Machinery                                                             $   32,368,249
--------------------------------------------------------------------------------------------------------------
                    Multiline Retail -- 0.7%
    88,271          Dollar General Corp.                                                        $   11,930,708
                                                                                                --------------
                    Total Multiline Retail                                                      $   11,930,708
--------------------------------------------------------------------------------------------------------------
                    Oil, Gas & Consumable Fuels -- 4.0%
   496,345          EOG Resources, Inc.                                                         $   46,239,500
   338,866          TOTAL SA (A.D.R.)                                                               18,905,334
                                                                                                --------------
                    Total Oil, Gas & Consumable Fuels                                           $   65,144,834
--------------------------------------------------------------------------------------------------------------
                    Pharmaceuticals -- 7.5%
   338,264          Eli Lilly & Co.                                                             $   37,476,268
   553,432          Merck & Co., Inc.                                                               46,405,273
   308,714          Novo Nordisk AS (A.D.R.)                                                        15,756,763
   192,663          Zoetis, Inc.                                                                    21,865,324
                                                                                                --------------
                    Total Pharmaceuticals                                                       $  121,503,628
--------------------------------------------------------------------------------------------------------------
                    Road & Rail -- 1.6%
    74,112          Kansas City Southern                                                        $    9,028,324
    80,791          Norfolk Southern Corp.                                                          16,104,070
                                                                                                --------------
                    Total Road & Rail                                                           $   25,132,394
--------------------------------------------------------------------------------------------------------------
                    Semiconductors & Semiconductor Equipment -- 1.4%
    58,606          Lam Research Corp.                                                          $   11,008,551
   319,895(a)       Micron Technology, Inc.                                                         12,344,748
                                                                                                --------------
                    Total Semiconductors & Semiconductor Equipment                              $   23,353,299
--------------------------------------------------------------------------------------------------------------


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

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/19 21



Schedule of Investments | 6/30/19 (unaudited) (continued)



--------------------------------------------------------------------------------------------------------------
Shares                                                                                          Value
--------------------------------------------------------------------------------------------------------------
                                                                                          
                    Software -- 8.8%
   109,393(a)       Adobe, Inc.                                                                 $   32,232,647
   704,997          Microsoft Corp.                                                                 94,441,398
   103,634(a)       salesforce.com, Inc.                                                            15,724,387
                                                                                                --------------
                    Total Software                                                              $  142,398,432
--------------------------------------------------------------------------------------------------------------
                    Specialty Retail -- 4.8%
   314,251          Home Depot, Inc.                                                            $   65,354,780
   238,971          TJX Cos., Inc.                                                                  12,636,787
                                                                                                --------------
                    Total Specialty Retail                                                      $   77,991,567
--------------------------------------------------------------------------------------------------------------
                    Technology Hardware, Storage & Peripherals -- 2.5%
   124,642          Apple, Inc.                                                                 $   24,669,145
   258,194          NetApp, Inc.                                                                    15,930,570
                                                                                                --------------
                    Total Technology Hardware, Storage & Peripherals                            $   40,599,715
--------------------------------------------------------------------------------------------------------------
                    Trading Companies & Distributors -- 1.0%
   124,613(a)       United Rentals, Inc.                                                        $   16,527,422
                                                                                                --------------
                    Total Trading Companies & Distributors                                      $   16,527,422
--------------------------------------------------------------------------------------------------------------
                    TOTAL COMMON STOCKS
                    (Cost $1,303,174,877)                                                       $1,538,458,131
--------------------------------------------------------------------------------------------------------------


--------------------------------------------------------------------------------------------------------------
Principal
Amount
USD ($)
--------------------------------------------------------------------------------------------------------------
                                                                                          
                    U.S. GOVERNMENT AND AGENCY OBLIGATIONS -- 3.1%
                    of Net Assets
10,000,000(b)       U.S. Treasury Bills, 7/2/19                                                 $    9,999,461
40,000,000(b)       U.S. Treasury Bills, 7/16/19                                                    39,965,854
--------------------------------------------------------------------------------------------------------------
                    TOTAL U.S. GOVERNMENT AND AGENCY OBLIGATIONS
                    (Cost $49,964,317)                                                          $   49,965,315
--------------------------------------------------------------------------------------------------------------
                    TOTAL INVESTMENTS IN UNAFFILIATED ISSUERS -- 98.1%
                    (Cost $1,353,139,194)                                                       $1,588,423,446
--------------------------------------------------------------------------------------------------------------
                    OTHER ASSETS AND LIABILITIES -- 1.9%                                        $   30,133,933
--------------------------------------------------------------------------------------------------------------
                    NET ASSETS -- 100.0%                                                        $1,618,557,379
==============================================================================================================


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

REIT       Real Estate Investment Trust.

(a)        Non-income producing security.

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

Purchases and sales of securities (excluding temporary cash investments) for
the six months ended June 30, 2019, aggregated $807,914,831 and $948,475,014,
respectively.

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

22 Pioneer Core Equity Fund | Semiannual Report | 6/30/19



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 six months ended June
30, 2019, the Fund did not engage in cross trade activity.

At June 30, 2019, the net unrealized appreciation on investments based on cost
for federal tax purposes of $1,354,588,892 was as follows:



                                                                             
       Aggregate gross unrealized appreciation for all investments in which
        there is an excess of value over tax cost                               $251,403,662
       Aggregate gross unrealized depreciation for all investments in which
        there is an excess of tax cost over value                                (17,569,108)
                                                                                ------------
       Net unrealized appreciation                                              $233,834,554
                                                                                ============


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 June 30, 2019, in valuing
the Fund's investments:



-----------------------------------------------------------------------------------------------------------
                                               Level 1           Level 2        Level 3    Total
-----------------------------------------------------------------------------------------------------------
                                                                               
Common Stocks                                  $1,538,458,131    $        --    $ --       $1,538,458,131
U.S. Government and
 Agency Obligations                                        --     49,965,315      --           49,965,315
-----------------------------------------------------------------------------------------------------------
 Total Investments in Securities               $1,538,458,131    $49,965,315    $ --       $1,588,423,446
===========================================================================================================


During the six months ended June 30, 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 | Semiannual Report | 6/30/19 23



Statement of Assets and Liabilities | 6/30/19 (unaudited)



                                                                              
ASSETS:
  Investments in unaffiliated issuers, at value (cost $1,353,139,194)            $1,588,423,446
  Cash                                                                               25,577,115
  Receivables --
     Investment securities sold                                                       4,673,227
     Fund shares sold                                                                    37,393
     Dividends                                                                          982,123
     Interest                                                                               279
  Other assets                                                                           64,468
-----------------------------------------------------------------------------------------------
       Total assets                                                              $1,619,758,051
===============================================================================================
LIABILITIES:
  Payables --
     Fund shares repurchased                                                     $      576,106
     Administrative fees                                                                 40,168
     Transfer agent fees                                                                118,582
     Shareowner communications expense                                                   17,611
     Registration fees                                                                  120,008
     Professional fees                                                                   26,306
     Printing expense                                                                    10,859
     Distributions                                                                       45,683
  Due to affiliates                                                                     168,821
  Accrued expenses                                                                       76,528
-----------------------------------------------------------------------------------------------
       Total liabilities                                                         $    1,200,672
===============================================================================================
NET ASSETS:
  Paid-in capital                                                                $1,381,543,988
  Distributable earnings                                                            237,013,391
-----------------------------------------------------------------------------------------------
       Net assets                                                                $1,618,557,379
===============================================================================================
NET ASSET VALUE PER SHARE:
No par value (unlimited number of shares authorized)
  Class A (based on $1,552,788,827/82,077,879 shares)                            $        18.92
  Class C (based on $10,388,503/635,483 shares)                                  $        16.35
  Class K (based on $34,698,416/1,833,287 shares)                                $        18.93
  Class R (based on $79,980/4,243 shares)                                        $        18.85
  Class Y (based on $20,601,653/1,073,252 shares)                                $        19.20
MAXIMUM OFFERING PRICE PER SHARE:
  Class A (based on $18.92 net asset value per share/100%-5.75%
     maximum sales charge)                                                       $        20.07
===============================================================================================


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

24 Pioneer Core Equity Fund | Semiannual Report | 6/30/19



Statement of Operations (unaudited)

For the Six Months Ended 6/30/19



                                                                                    
INVESTMENT INCOME:
  Dividends from unaffiliated issuers (net of foreign taxes
     withheld $297,475)                                                  $14,126,154
  Interest from unaffiliated issuers                                         417,865
-------------------------------------------------------------------------------------------------------
       Total investment income                                                            $ 14,544,019
-------------------------------------------------------------------------------------------------------
EXPENSES:
  Management fees                                                        $ 3,918,813
  Administrative expense                                                     310,130
  Transfer agent fees
     Class A                                                                 467,408
     Class C                                                                   4,893
     Class K                                                                      30
     Class R                                                                      48
     Class Y                                                                   8,995
  Distribution fees
     Class A                                                               1,872,367
     Class C                                                                  50,926
     Class R                                                                     194
  Shareowner communications expense                                          181,335
  Custodian fees                                                              10,592
  Registration fees                                                           37,987
  Professional fees                                                           53,795
  Printing expense                                                            13,992
  Pricing fees                                                                    26
  Trustees' fees                                                              34,253
  Miscellaneous                                                               48,685
-------------------------------------------------------------------------------------------------------
     Total expenses                                                                       $  7,014,469
-------------------------------------------------------------------------------------------------------
       Net investment income                                                              $  7,529,550
-------------------------------------------------------------------------------------------------------
REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS:
  Net realized gain (loss) on:
     Investments in unaffiliated issuers                                 $26,823,755
     Class actions                                                           145,613      $ 26,969,368
-------------------------------------------------------------------------------------------------------
  Change in net unrealized appreciation (depreciation) on:
     Investments in unaffiliated issuers                                                  $230,686,093
-------------------------------------------------------------------------------------------------------
  Net realized and unrealized gain (loss) on investments                                  $257,655,461
-------------------------------------------------------------------------------------------------------
  Net increase in net assets resulting from operations                                    $265,185,011
=======================================================================================================


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

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/19 25



Statements of Changes in Net Assets



-----------------------------------------------------------------------------------------------------
                                                                 Six Months
                                                                 Ended
                                                                 6/30/19              Year Ended
                                                                 (unaudited)          12/31/18
-----------------------------------------------------------------------------------------------------
                                                                                
FROM OPERATIONS:
Net investment income (loss)                                     $    7,529,550       $   14,079,863
Net realized gain (loss) on investments                              26,969,368          173,931,495
Change in net unrealized appreciation (depreciation)
  on investments                                                    230,686,093         (321,835,356)
-----------------------------------------------------------------------------------------------------
     Net increase (decrease) in net assets resulting
       from operations                                           $  265,185,011       $ (133,823,998)
-----------------------------------------------------------------------------------------------------
DISTRIBUTIONS TO SHAREOWNERS:
     Class A ($-- and $3.14 per share, respectively)             $           --       $ (233,691,543)
     Class C ($-- and $3.00 per share, respectively)                         --           (1,717,954)
     Class K ($-- and $3.21 per share, respectively)                         --           (7,608,473)
     Class R ($-- and $3.16 per share, respectively)                         --               (7,560)
     Class Y ($-- and $3.17 per share, respectively)                         --           (3,167,681)
-----------------------------------------------------------------------------------------------------
       Total distributions to shareowners                        $           --       $ (246,193,211)
-----------------------------------------------------------------------------------------------------
FROM FUND SHARE TRANSACTIONS:
Net proceeds from sales of shares                                $   12,800,199       $  140,655,901
Reinvestment of distributions                                                --          228,799,836
Cost of shares repurchased                                          (91,684,742)        (259,838,454)
-----------------------------------------------------------------------------------------------------
     Net increase (decrease) in net assets resulting
       from Fund share transactions                              $  (78,884,543)      $  109,617,283
-----------------------------------------------------------------------------------------------------
     Net increase (decrease) in net assets                       $  186,300,468       $ (270,399,926)
NET ASSETS:
Beginning of period                                              $1,432,256,911       $1,702,656,837
-----------------------------------------------------------------------------------------------------
End of period                                                    $1,618,557,379       $1,432,256,911
=====================================================================================================


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

26 Pioneer Core Equity Fund | Semiannual Report | 6/30/19





---------------------------------------------------------------------------------------------------------------
                                             Six Months       Six Months
                                             Ended            Ended
                                             6/30/19          6/30/19           Year Ended      Year Ended
                                             Shares           Amount            12/31/18        12/31/18
                                             (unaudited)      (unaudited)       Shares          Amount
---------------------------------------------------------------------------------------------------------------
                                                                                    
Class A
Shares sold                                     442,948       $  7,927,022       1,303,566      $  26,373,832
Reinvestment of distributions                        --                 --      12,709,821        224,191,051
Less shares repurchased                      (3,972,942)       (71,749,886)     (7,588,320)      (156,138,331)
---------------------------------------------------------------------------------------------------------------
     Net increase (decrease)                 (3,529,994)      $(63,822,864)      6,425,067      $  94,426,552
===============================================================================================================
Class C
Shares sold                                      33,693       $    516,439         184,961      $   3,251,927
Reinvestment of distributions                        --                 --         107,229          1,638,461
Less shares repurchased                         (79,605)        (1,232,234)       (375,379)        (6,949,337)
---------------------------------------------------------------------------------------------------------------
     Net decrease                               (45,912)      $   (715,795)        (83,189)     $  (2,058,949)
===============================================================================================================
Class K
Shares sold                                      89,103       $  1,576,449       3,470,577      $  73,585,363
Reinvestment of distributions                        --                 --          22,127            346,284
Less shares repurchased                        (879,344)       (15,648,282)       (869,176)       (17,731,891)
---------------------------------------------------------------------------------------------------------------
     Net increase (decrease)                   (790,241)      $(14,071,833)      2,623,528      $  56,199,756
===============================================================================================================
Class R
Shares sold                                       3,871       $     67,852           2,372      $      50,000
Reinvestment of distributions                        --                 --             429              7,560
Less shares repurchased                          (2,429)           (45,325)             --                 --
---------------------------------------------------------------------------------------------------------------
     Net increase                                 1,442       $     22,527           2,801      $      57,560
===============================================================================================================
Class Y
Shares sold                                     146,925       $  2,712,437       1,744,626      $  37,394,779
Reinvestment of distributions                        --                 --         146,312          2,616,480
Less shares repurchased                        (164,275)        (3,009,015)     (3,626,653)       (79,018,895)
---------------------------------------------------------------------------------------------------------------
     Net decrease                               (17,350)      $   (296,578)     (1,735,715)     $ (39,007,636)
===============================================================================================================


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

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/19 27



Financial Highlights



------------------------------------------------------------------------------------------------------------------------------------
                                              Six Months
                                              Ended          Year            Year          Year          Year            Year
                                              6/30/19        Ended           Ended         Ended         Ended           Ended
                                              (unaudited)    12/31/18        12/31/17      12/31/16*     12/31/15*       12/31/14*
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                       
Class A
Net asset value, beginning of period          $    15.93     $    20.58      $    18.01    $    16.80    $    17.18      $    15.70
------------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment
  operations:
  Net investment income (loss)                $     0.09(a)  $     0.17(a)   $     0.17(a) $     0.19(a) $     0.13(a)   $     0.18
  Net realized and unrealized gain (loss)
  on investments                                    2.90          (1.68)           4.26          1.22         (0.39)           1.46
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment
  operations                                  $     2.99     $    (1.51)     $     4.43    $     1.41    $    (0.26)     $     1.64
------------------------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
  Net investment income                       $       --     $    (0.14)     $    (0.16)   $    (0.20)   $    (0.12)     $    (0.16)
  Net realized gain                                   --          (3.00)          (1.70)           --            --              --
------------------------------------------------------------------------------------------------------------------------------------
Total distributions                           $       --     $    (3.14)     $    (1.86)   $    (0.20)   $    (0.12)     $    (0.16)
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value    $     2.99     $    (4.65)     $     2.57    $     1.21    $    (0.38)     $     1.48
------------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                $    18.92     $    15.93      $    20.58    $    18.01    $    16.80      $    17.18
====================================================================================================================================
Total return (b)                                   18.77%(c)      (8.70)%(d)      24.77%         8.39%        (1.49)%(e)      10.44%
Ratio of net expenses to average net
  assets (f)                                        0.90%(g)       0.90%           0.89%         0.94%         0.93%           0.94%
Ratio of net investment income (loss)
  to average net assets                             0.95%(g)       0.82%           0.85%         1.15%         0.75%           1.03%
Portfolio turnover rate                               53%(c)        114%             81%           80%          100%             57%
Net assets, end of period (in thousands)      $1,552,789     $1,363,460      $1,629,908    $1,436,208    $1,450,815      $1,605,301
====================================================================================================================================


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

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

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

(c)   Not annualized.

(d)   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)%.

(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 (1.55)%.

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

(g)   Annualized.

+     Amount rounds to less than 0.01%.

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

28 Pioneer Core Equity Fund | Semiannual Report | 6/30/19





------------------------------------------------------------------------------------------------------------------------------------
                                                              Six Months
                                                              Ended       Year        Year       Year       Year           Year
                                                              6/30/19     Ended       Ended      Ended      Ended          Ended
                                                              (unaudited) 12/31/18    12/31/17   12/31/16*  12/31/15*      12/31/14*
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                         
Class C
Net asset value, beginning of period                          $ 13.82     $18.26      $ 16.17    $ 15.11    $ 15.48        $ 14.19
------------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations:
  Net investment income (loss)                                $  0.01(a)  $ 0.00+(a)  $  0.01(a) $  0.05(a) $ (0.01)(a)(b) $  0.02
  Net realized and unrealized gain (loss) on investments         2.52      (1.44)        3.80       1.10      (0.35)          1.33
-----------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations            $  2.53     $(1.44)     $  3.81    $  1.15    $ (0.36)       $  1.35
------------------------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
  Net investment income                                       $    --     $   --      $ (0.02)   $ (0.09)   $ (0.01)       $ (0.06)
  Net realized gain                                                --      (3.00)       (1.70)        --         --             --
------------------------------------------------------------------------------------------------------------------------------------
Total distributions                                           $    --     $(3.00)     $ (1.72)   $ (0.09)   $ (0.01)       $ (0.06)
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                    $  2.53     $(4.44)     $  2.09    $  1.06    $ (0.37)       $  1.29
------------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                                $ 16.35     $13.82      $ 18.26    $ 16.17    $ 15.11        $ 15.48
====================================================================================================================================
Total return (c)                                                18.31%(d)  (9.45)%(e)   23.74%      7.58%     (2.34)%(f)      9.52%
Ratio of net expenses to average net assets (g)                  1.72%(h)   1.69%        1.71%      1.76%      1.74%          1.81%
Ratio of net investment income (loss) to average net assets      0.14%(h)   0.02%        0.04%      0.33%     (0.06)%         0.14%
Portfolio turnover rate                                            53%(d)    114%          81%        80%       100%            57%
Net assets, end of period (in thousands)                      $10,389     $9,416      $13,961    $13,016    $14,106        $13,848
====================================================================================================================================


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

(a)   The per-share data presented above is based on the average shares
      outstanding for the 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)   Not annualized.

(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)%.

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

(h)   Annualized.

+     Amount rounds to less than 0.01%.

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

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/19 29



Financial Highlights (continued)



-----------------------------------------------------------------------------------------------------------
                                                                          Six Months
                                                                          Ended
                                                                          6/30/19             5/4/18* to
                                                                          (unaudited)         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)                                        $  0.12           $  0.16
  Net realized and unrealized gain (loss) on investments                     2.90             (1.86)
-----------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations                        $  3.02           $ (1.70)
-----------------------------------------------------------------------------------------------------------
Distributions to shareowners:
  Net investment income                                                   $    --           $ (0.21)
  Net realized gain                                                            --             (3.00)
-----------------------------------------------------------------------------------------------------------
Total distributions                                                       $    --           $ (3.21)
-----------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                                $  3.02           $ (4.91)
-----------------------------------------------------------------------------------------------------------
Net asset value, end of period                                            $ 18.93           $ 15.91
===========================================================================================================
Total return (b)                                                            18.98%(c)(d)      (8.47)%(c)(e)
Ratio of net expenses to average net assets                                  0.56%(f)          0.57%(f)
Ratio of net investment income (loss) to average net assets                  1.31%(f)          1.17%(f)
Portfolio turnover rate                                                        53%(c)           114%(c)
Net assets, end of period (in thousands)                                  $34,698           $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)   Not annualized.

(d)   If the Fund had not recognized gains in settlement of class action
      lawsuits during the six months ended June 30, 2019, the total return would
      have been 18.92%.

(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 (8.51)%.

(f)   Annualized.

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

30 Pioneer Core Equity Fund | Semiannual Report | 6/30/19





---------------------------------------------------------------------------------------------------------------
                                                                           Six Months
                                                                           Ended
                                                                           6/30/19              6/29/18* to
                                                                           (unaudited)          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)                                         $ 0.05               $ 0.06
  Net realized and unrealized gain (loss) on investments                     2.90                (2.08)
---------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations                         $ 2.95               $(2.02)
---------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
  Net investment income                                                    $   --               $(0.16)
  Net realized gain                                                            --                (3.00)
---------------------------------------------------------------------------------------------------------------
Total distributions                                                        $   --               $(3.16)
---------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                                 $ 2.95               $(5.18)
---------------------------------------------------------------------------------------------------------------
Net asset value, end of period                                             $18.85               $15.90
===============================================================================================================
=Total return (b)                                                            18.55%(c)            (8.76)%(c)(d)
Ratio of net expenses to average net assets                                  1.27%(e)             1.06%(e)
Ratio of net investment income (loss) to average net assets                  0.55%(e)             0.62%(e)
Portfolio turnover rate                                                        53%(c)              114%(c)
Net assets, end of period (in thousands)                                   $   80               $   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)   Not annualized.

(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 (8.80)%.

(e)   Annualized.

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

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/19 31



Financial Highlights (continued)



------------------------------------------------------------------------------------------------------------------------------------
                                                              Six Months
                                                              Ended       Year        Year       Year       Year           Year
                                                              6/30/19     Ended       Ended      Ended      Ended          Ended
                                                              (unaudited) 12/31/18    12/31/17   12/31/16*  12/31/15*      12/31/14*
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                         
Class Y
Net asset value, beginning of period                        $ 16.14        $ 20.80      $ 18.18    $ 16.95    $ 17.34      $ 15.85
------------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations:
  Net investment income (loss)                              $  0.11(a)     $  0.22(a)   $  0.22(a) $  0.25(a) $  0.19(a)   $  0.20
  Net realized and unrealized gain (loss) on investments       2.95          (1.71)        4.32       1.23      (0.40)        1.51
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations          $  3.06        $ (1.49)     $  4.54    $  1.48    $ (0.21)     $  1.71
------------------------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
  Net investment income                                     $    --        $ (0.17)     $ (0.22)   $ (0.25)   $ (0.18)     $ (0.22)
  Net realized gain                                              --          (3.00)       (1.70)        --         --           --
------------------------------------------------------------------------------------------------------------------------------------
Total distributions                                         $    --        $ (3.17)     $ (1.92)   $ (0.25)   $ (0.18)     $ (0.22)
------------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                  $  3.06        $ (4.66)     $  2.62    $  1.23    $ (0.39)     $  1.49
------------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                              $ 19.20        $ 16.14      $ 20.80    $ 18.18    $ 16.95      $ 17.34
====================================================================================================================================
Total return (b)                                              18.96%(c)(d)   (8.53)%(e)   25.10%      8.73%     (1.21)%(f)   10.75%
Ratio of net expenses to average net assets (g)                0.66%(h)       0.64%        0.63%      0.63%      0.62%        0.63%
Ratio of net investment income (loss) to average net assets    1.19%(h)       1.05%        1.11%      1.47%      1.07%        1.37%
Portfolio turnover rate                                          53%(c)        114%          81%        80%       100%          57%
Net assets, end of period (in thousands)                    $20,602        $17,603      $58,788    $44,915    $62,206      $66,424
====================================================================================================================================


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

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

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

(c)   Not annualized.

(d)   If the Fund had not recognized gains in settlement of class action
      lawsuits during the six months ended June 30, 2019, the total return would
      have been 18.90%.

(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 (8.60)%.

(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 (1.27)%.

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

(h)   Annualized.

+     Amount rounds to less than 0.01%.

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

32 Pioneer Core Equity Fund | Semiannual Report | 6/30/19



Notes to Financial Statements | 6/30/19 (unaudited)

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 | Semiannual Report | 6/30/19 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.

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

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

34 Pioneer Core Equity Fund | Semiannual Report | 6/30/19



      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.

      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 June 30, 2019, no securities were valued using fair value methods
      (other than securities valued using prices supplied by independent pricing
      services, broker-dealers or using a third party insurance industry pricing
      model).

B.    Investment Income and Transactions

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

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

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/19 35



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

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

C.    Foreign Currency Translation

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

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

D.    Federal Income Taxes

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

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

36 Pioneer Core Equity Fund | Semiannual Report | 6/30/19



      The tax character of current year distributions payable will be determined
      at the end of the current taxable year. The tax character of distributions
      paid during the year ended December 31, 2018 was as follows:



      --------------------------------------------------------------------------
                                                                           2018
      --------------------------------------------------------------------------
                                                                
      Distributions paid from:
      Ordinary income                                              $ 29,689,577
      Long-term capital gain                                        216,503,634
      --------------------------------------------------------------------------
          Total                                                    $246,193,211
      ==========================================================================


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



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


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

E.    Fund Shares

      The Fund records sales and repurchases of its shares as of trade date. The
      Distributor earned $20,618 in underwriting commissions on the sale of
      Class A shares during the six months ended June 30, 2019.

F.    Class Allocations

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

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


                       Pioneer Core Equity Fund | Semiannual Report | 6/30/19 37



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

G.    Risks

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

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

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

38 Pioneer Core Equity Fund | Semiannual Report | 6/30/19



      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.

H.    Repurchase Agreements

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

      As of and for the six months ended June 30, 2019, the Fund had no open
      repurchase agreements.

2. Management Agreement

The Adviser manages the Fund's portfolio. Effective October 1, 2018, management
fees are calculated daily at the annual of the Fund's average daily net assets
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. Prior to October 1,
2018, management fees were calculated daily at the annual rate of 0.50% of the
Fund's average daily net assets. For the six months ended June 30, 2019, the
effective management fee was equivalent to 0.50% (annualized) of the Fund's
average daily net assets.

In addition, under the management and administration agreements, certain other
services and costs, including accounting, regulatory reporting and insurance
premiums, are paid by the Fund as administrative reimbursements.

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/19 39



Included in "Due to affiliates" reflected on the Statement of Assets and
Liabilities is $114,533 in management fees, administrative costs and certain
other reimbursements payable to the Adviser at June 30, 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 six
months ended June 30, 2019, such out-of-pocket expenses by class of shares were
as follows:



--------------------------------------------------------------------------------
Shareowner Communications:
--------------------------------------------------------------------------------
                                                                    
Class A                                                                $178,180
Class C                                                                   2,806
Class K                                                                       9
Class R                                                                      32
Class Y                                                                     308
--------------------------------------------------------------------------------
 Total                                                                 $181,335
================================================================================


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.
Included in "Due to affiliates" reflected on the Statement of Assets and
Liabilities is $54,288 in distribution fees payable to the Distributor at June
30, 2019.

The Fund also has adopted a separate service plan for Class R shares (the
"Service Plan"). The Service Plan authorizes the Fund to pay securities
dealers, plan administrators or other service organizations that agree to
provide certain

40 Pioneer Core Equity Fund | Semiannual Report | 6/30/19



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 six months ended June 30, 2019, CDSCs in the amount
of $371 were paid to the Distributor.

5. Line of Credit Facility

The Fund, along with certain other funds in the Pioneer Family of Funds (the
"Funds"), participates in a committed, unsecured revolving line of credit
facility. Borrowings are used solely for temporary or emergency purposes. The
Fund may borrow up to the lesser of the amount available under the facility or
the limits set for borrowing by the Fund's prospectus and the 1940 Act.
Effective August 1, 2018, the Fund participates in a credit facility in the
amount of $250 million. Under such facility, depending on the type of loan,
interest on borrowings is payable at the London Interbank Offered Rate
("LIBOR") plus 0.90% on an annualized basis, or the Alternate Base Rate, which
is the greater of (a) the facility's administrative agent's daily announced
prime rate on the borrowing date, (b) 2% plus the Federal Funds Rate on the
borrowing date, or (c) 2% plus the overnight Eurodollar rate on the borrowing
date. The Funds pay an annual commitment fee to participate in a credit
facility. The commitment fee is allocated among participating Funds based on an
allocation schedule set forth in the credit agreement. For the six months ended
June 30, 2019 the Fund had no borrowings under the credit facility.

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/19 41



Trustees, Officers and Service Providers

Trustees                           Officers
Thomas J. Perna, Chairman          Lisa M. Jones, President and
David R. Bock                        Chief Executive Officer
Diane Durnin                       Mark E. Bradley, Treasurer and
Benjamin M. Friedman                 Chief Financial and
Margaret B.W. Graham                 Accounting Officer
Lisa M. Jones                      Christopher J. Kelley, Secretary and
Lorraine H. Monchak                  Chief Legal Officer
Marguerite A. Piret
Fred J. Ricciardi
Kenneth J. Taubes

Investment Adviser and Administrator
Amundi Pioneer Asset Management, Inc.

Custodian and Sub-Administrator
Brown Brothers Harriman & Co.

Principal Underwriter
Amundi Pioneer Distributor, Inc.

Legal Counsel
Morgan, Lewis & Bockius LLP

Transfer Agent
DST Asset Manager Solutions, Inc.

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

42 Pioneer Core Equity Fund | Semiannual Report | 6/30/19



                          This page is for your notes.

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/19 43



                          This page is for your notes.

44 Pioneer Core Equity Fund | Semiannual Report | 6/30/19




How to Contact Amundi Pioneer

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

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

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

Retirement plans information                                      1-800-622-0176

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

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

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

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

This report must be preceded or accompanied by a prospectus.

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



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

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

Securities offered through Amundi Pioneer Distributor, Inc.
60 State Street, Boston, MA 02109
Underwriter of Pioneer Mutual Funds, Member SIPC
[C] 2019 Amundi Pioneer Asset Management 19408-13-0819




ITEM 2. CODE OF ETHICS.

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

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

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

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

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

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

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

        (5) Accountability for adherence to the code.

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

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

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

Not applicable.

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

Not applicable.

(f) The registrant must:

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

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

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

ITEM 3. AUDIT COMMITTEE FINANCIAL EXPERT.

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

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

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

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

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

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

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

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

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

Not applicable.


ITEM 4. PRINCIPAL ACCOUNTANT FEES AND SERVICES.

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

N/A

(b) Disclose, under the caption AUDIT-RELATED FEES, the aggregate fees billed in
each of the last two fiscal years for assurance and related services by the
principal accountant that are reasonably related to the performance of the audit
of the registrant's financial statements and are not reported under
paragraph (a) of this Item. Registrants shall describe the nature of the
services comprising the fees disclosed under this category.

N/A

(c) Disclose, under the caption TAX FEES, the aggregate fees billed in each of
the last two fiscal years for professional services rendered by the principal
accountant for tax compliance, tax advice, and tax planning. Registrants shall
describe the nature of the services comprising the fees disclosed under this
category.

N/A

(d) Disclose, under the caption ALL OTHER FEES, the aggregate fees billed in
each of the last two fiscal years for products and services provided by the
principal accountant, other than the services reported in paragraphs (a) through
(c) of this Item. Registrants shall describe the nature of the services
comprising the fees disclosed under this category.

N/A

(e) (1) Disclose the audit committee's pre-approval policies and procedures
described in paragraph (c)(7) of Rule 2-01 of Regulation S-X.

 PIONEER FUNDS
            APPROVAL OF AUDIT, AUDIT-RELATED, TAX AND OTHER SERVICES
                       PROVIDED BY THE INDEPENDENT AUDITOR

                  SECTION I - POLICY PURPOSE AND APPLICABILITY

The Pioneer Funds recognize the importance of maintaining the independence of
their outside auditors. Maintaining independence is a shared responsibility
involving Amudi Pioneer Asset Management, Inc, the audit committee and
the independent auditors.

The Funds recognize that a Fund's independent auditors: 1) possess knowledge of
the Funds, 2) are able to incorporate certain services into the scope of the
audit, thereby avoiding redundant work, cost and disruption of Fund personnel
and processes, and 3) have expertise that has value to the Funds. As a result,
there are situations where it is desirable to use the Fund's independent
auditors for services in addition to the annual audit and where the potential
for conflicts of interests are minimal. Consequently, this policy, which is
intended to comply with Rule 210.2-01(C)(7), sets forth guidelines and
procedures to be followed by the Funds when retaining the independent audit firm
to perform audit, audit-related tax and other services under those
circumstances, while also maintaining independence.

Approval of a service in accordance with this policy for a Fund shall also
constitute approval for any other Fund whose pre-approval is required pursuant
to Rule 210.2-01(c)(7)(ii).

In addition to the procedures set forth in this policy, any non-audit services
that may be provided consistently with Rule 210.2-01 may be approved by the
Audit Committee itself and any pre-approval that may be waived in accordance
with Rule 210.2-01(c)(7)(i)(C) is hereby waived.

Selection of a Fund's independent auditors and their compensation shall be
determined by the Audit Committee and shall not be subject to this policy.



                               SECTION II - POLICY

---------------- -------------------------------- -------------------------------------------------
SERVICE           SERVICE CATEGORY DESCRIPTION      SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES
CATEGORY
---------------- -------------------------------- -------------------------------------------------
                                            
I.  AUDIT        Services that are directly       o Accounting research assistance
SERVICES         related to performing the        o SEC consultation, registration
                 independent audit of the Funds     statements, and reporting
                                                  o Tax accrual related matters
                                                  o Implementation of new accounting
                                                    standards
                                                  o Compliance letters (e.g. rating agency
                                                    letters)
                                                  o Regulatory reviews and assistance
                                                    regarding financial matters
                                                  o Semi-annual reviews (if requested)
                                                  o Comfort letters for closed end
                                                    offerings
---------------- -------------------------------- -------------------------------------------------
II.              Services which are not           o AICPA attest and agreed-upon procedures
AUDIT-RELATED    prohibited under Rule            o Technology control assessments
SERVICES         210.2-01(C)(4) (the "Rule")      o Financial reporting control assessments
                 and are related extensions of    o Enterprise security architecture
                 the audit services support the     assessment
                 audit, or use the
                 knowledge/expertise gained
                 from the audit procedures as a
                 foundation to complete the
                 project.  In most cases, if
                 the Audit-Related Services are
                 not performed by the Audit
                 firm, the scope of the Audit
                 Services would likely
                 increase.  The Services are
                 typically well-defined and
                 governed by accounting
                 professional standards (AICPA,
                 SEC, etc.)
---------------- -------------------------------- -------------------------------------------------

 ------------------------------------- ------------------------------------
                                    
   AUDIT COMMITTEE APPROVAL POLICY               AUDIT COMMITTEE
                                                REPORTING POLICY
 ------------------------------------- ------------------------------------
                                    
 o "One-time" pre-approval             o A summary of all such
   for the audit period for all          services and related fees
   pre-approved specific service         reported at each regularly
   subcategories.  Approval of the       scheduled Audit Committee
   independent auditors as               meeting.
   auditors for a Fund shall
   constitute pre approval for
   these services.
 ------------------------------------- ------------------------------------
 o "One-time" pre-approval             o A summary of all such
   for the fund fiscal year within       services and related fees
   a specified dollar limit              (including comparison to
   for all pre-approved                  specified dollar limits)
   specific service subcategories        reported quarterly.

 o Specific approval is
   needed to exceed the
   pre-approved dollar limit for
   these services (see general
   Audit Committee approval policy
   below for details on obtaining
   specific approvals)

 o Specific approval is
   needed to use the Fund's
   auditors for Audit-Related
   Services not denoted as
   "pre-approved", or
   to add a specific service
   subcategory as "pre-approved"
 ------------------------------------- ------------------------------------




                     SECTION III - POLICY DETAIL, CONTINUED

----------------------- --------------------------- -----------------------------------------------
   SERVICE CATEGORY          SERVICE CATEGORY        SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES
                               DESCRIPTION
----------------------- --------------------------- -----------------------------------------------
                                              
III. TAX SERVICES       Services which are not      o Tax planning and support
                        prohibited by the Rule,     o Tax controversy assistance
                        if an officer of the Fund   o Tax compliance, tax returns, excise
                        determines that using the     tax returns and support
                        Fund's auditor to provide   o Tax opinions
                        these services creates
                        significant synergy in
                        the form of efficiency,
                        minimized disruption, or
                        the ability to maintain a
                        desired level of
                        confidentiality.
----------------------- --------------------------- -----------------------------------------------

------------------------------------- -------------------------
  AUDIT COMMITTEE APPROVAL POLICY         AUDIT COMMITTEE
                                          REPORTING POLICY
------------------------------------- -------------------------
------------------------------------- -------------------------
o "One-time" pre-approval             o A summary of
  for the fund fiscal  year             all such services and
  within a specified dollar limit       related fees
  				        (including comparison
  			                to specified dollar
  			                limits) reported
  			                quarterly.

o Specific approval is
  needed to exceed the
  pre-approved dollar limits for
  these services (see general
  Audit Committee approval policy
  below for details on obtaining
  specific approvals)

o Specific approval is
  needed to use the Fund's
  auditors for tax services not
  denoted as pre-approved, or to add a specific
  service subcategory as
  "pre-approved"
------------------------------------- -------------------------




                     SECTION III - POLICY DETAIL, CONTINUED

----------------------- --------------------------- -----------------------------------------------
   SERVICE CATEGORY          SERVICE CATEGORY        SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES
                               DESCRIPTION
----------------------- --------------------------- -----------------------------------------------
                                              
IV.  OTHER SERVICES     Services which are not      o Business Risk Management support
                        prohibited by the Rule,     o Other control and regulatory
A. SYNERGISTIC,         if an officer of the Fund     compliance projects
UNIQUE QUALIFICATIONS   determines that using the
                        Fund's auditor to provide
                        these services creates
                        significant synergy in
                        the form of efficiency,
                        minimized disruption,
                        the ability to maintain a
                        desired level of
                        confidentiality, or where
                        the Fund's auditors
                        posses unique or superior
                        qualifications to provide
                        these services, resulting
                        in superior value and
                        results for the Fund.
----------------------- --------------------------- -----------------------------------------------

--------------------------------------- ------------------------
    AUDIT COMMITTEE APPROVAL POLICY         AUDIT COMMITTEE
                                            REPORTING POLICY
------------------------------------- --------------------------
                                   
o "One-time" pre-approval             o A summary of
  for the fund fiscal year within       all such services and
  a specified dollar limit              related fees
  			               (including comparison
  			                to specified dollar
  				        limits) reported
                                        quarterly.
o Specific approval is
  needed to exceed the
  pre-approved dollar limits for
  these services (see general
  Audit Committee approval policy
  below for details on obtaining
  specific approvals)

o Specific approval is
  needed to use the Fund's
  auditors for "Synergistic" or
  "Unique Qualifications" Other
  Services not denoted as
  pre-approved to the left, or to
  add a specific service
  subcategory as "pre-approved"
------------------------------------- --------------------------




                     SECTION III - POLICY DETAIL, CONTINUED

----------------------- ------------------------- -----------------------------------------------
   SERVICE CATEGORY         SERVICE CATEGORY        SPECIFIC PROHIBITED SERVICE SUBCATEGORIES
                              DESCRIPTION
----------------------- ------------------------- -----------------------------------------------
                                            
PROHIBITED  SERVICES    Services which result     1. Bookkeeping or other services
                        in the auditors losing       related to the accounting records or
                        independence status          financial statements of the audit
                        under the Rule.              client*
                                                  2. Financial information systems design
                                                     and implementation*
                                                  3. Appraisal or valuation services,
                                                     fairness* opinions, or
                                                     contribution-in-kind reports
                                                  4. Actuarial services (i.e., setting
                                                     actuarial reserves versus actuarial
                                                     audit work)*
                                                  5. Internal audit outsourcing services*
                                                  6. Management functions or human
                                                     resources
                                                  7. Broker or dealer, investment
                                                     advisor, or investment banking services
                                                  8. Legal services and expert services
                                                     unrelated to the audit
                                                  9. Any other service that the Public
                                                     Company Accounting Oversight Board
                                                     determines, by regulation, is
                                                     impermissible
----------------------- ------------------------- -----------------------------------------------

------------------------------------------- ------------------------------
     AUDIT COMMITTEE APPROVAL POLICY               AUDIT COMMITTEE
                                                  REPORTING POLICY
------------------------------------------- ------------------------------
o These services are not to be              o A summary of all
  performed with the exception of the(*)      services and related
  services that may be permitted              fees reported at each
  if they would not be subject to audit       regularly scheduled
  procedures at the audit client (as          Audit Committee meeting
  defined in rule 2-01(f)(4)) level           will serve as continual
  the firm providing the service.             confirmation that has
  				              not provided any
                                              restricted services.
------------------------------------------- ------------------------------

--------------------------------------------------------------------------------
GENERAL AUDIT COMMITTEE APPROVAL POLICY:
o For all projects, the officers of the Funds and the Fund's auditors will each
  make an assessment to determine that any proposed projects will not impair
  independence.

o Potential services will be classified into the four non-restricted service
  categories and the "Approval of Audit, Audit-Related, Tax and Other
  Services" Policy above will be applied. Any services outside the specific
  pre-approved service subcategories set forth above must be specifically
  approved by the Audit Committee.

o At least quarterly, the Audit Committee shall review a report summarizing the
  services by service category, including fees, provided by the Audit firm as
  set forth in the above policy.

--------------------------------------------------------------------------------


    (2) Disclose the percentage of services described in each of paragraphs (b)
   through (d) of this Item that were approved by the audit committee pursuant
   to paragraph (c)(7)(i)(C) of Rule 2-01 of Regulation S-X.

Non-Audit Services
N/A


(f) If greater than 50 percent, disclose the percentage of hours expended on the
principal accountants engagement to audit the registrant's financial statements
for the most recent fiscal year that were attributed to work performed by
persons other than the principal accountant's full-time, permanent employees.

N/A

(g) Disclose the aggregate non-audit fees billed by the registrants accountant
for services rendered to the registrant, and rendered to the registrants
investment adviser (not including any sub-adviser whose role is primarily
portfolio management and is subcontracted with or overseen by another investment
adviser), and any entity controlling, controlled by, or under common control
with the adviser that provides ongoing services to the registrant for each of
the last two fiscal years of the registrant.

N/A

(h) Disclose whether the registrants audit committee of the board of trustees
has considered whether the provision of non-audit services that were rendered to
the registrants investment adviser (not including any subadviser whose role is
primarily portfolio management and is subcontracted with or overseen by another
investment adviser), and any entity controlling, controlled by, or under common
control with the investment adviser that provides ongoing services to the
registrant that were not pre-approved pursuant to paragraph (c)(7)(ii) of
Rule 2-01 of Regulation S-X is compatible with maintaining the principal
accountant's independence.

The Fund's audit committee of the Board of Trustees
has considered whether the provision of non-audit
services that were rendered to the Affiliates (as
defined) that were not pre- approved pursuant to
paragraph (c)(7)(ii) of Rule 2-01 of Regulation S-X is
compatible with maintaining the principal accountant's
independence.

ITEM 5. AUDIT COMMITTEE OF LISTED REGISTRANTS

(a) If the registrant is a listed issuer as defined in Rule 10A-3
under the Exchange Act (17 CFR 240.10A-3), state whether
or not the registrant has a separately-designated standing
 audit committee established in accordance with Section
3(a)(58)(A) of the Exchange Act (15 U.S.C. 78c(a)(58)(A)).
If the registrant has such a committee, however designated,
identify each committee member. If the entire board of directors
is acting as the registrant's audit committee as specified in
Section 3(a)(58)(B) of the Exchange Act (15 U.S.C. 78c(a)(58)(B)),
so state.

N/A

(b) If applicable, provide the disclosure required by Rule 10A-3(d)
under the Exchange Act (17 CFR 240.10A-3(d)) regarding an exemption
from the listing standards for audit committees.

N/A

ITEM 6. SCHEDULE OF INVESTMENTS.

File Schedule of Investments in securities of unaffiliated issuers
as of the close of the reporting period as set forth in 210.1212
of Regulation S-X [17 CFR 210.12-12], unless the schedule is
included as part of the report to shareholders filed under Item
1 of this Form.

Included in Item 1


ITEM 7. DISCLOSURE OF PROXY VOTING POLICIES AND PROCEDURES FOR
CLOSED-END MANAGEMENT INVESTMENT COMPANIES.

A closed-end management investment company that is filing an annual report on
this Form N-CSR must, unless it invests exclusively in non-voting securities,
describe the policies and procedures that it uses to determine how to vote
proxies relating to portfolio securities, including the procedures that the
company uses when a vote presents a conflict between the interests of its
shareholders, on the one hand, and those of the company's investment adviser;
principal underwriter; or any affiliated person (as defined in Section 2(a)(3)
of the Investment Company Act of 1940 (15 U.S.C. 80a-2(a)(3)) and the rules
thereunder) of the company, its investment adviser, or its principal
underwriter, on the other. Include any policies and procedures of the company's
investment adviser, or any other third party, that the company uses, or that are
used on the company's behalf, to determine how to vote proxies relating to
portfolio securities.

Not applicable to open-end management investment companies.



ITEM 8. PORTFOLIO MANAGERS OF CLOSED-END MANAGEMENT INVESTMENT COMPANIES.

(a) If the registrant is a closed-end management investment company that
is filing an annual report on this Form N-CSR,provide the following
information:
(1) State the name, title, and length of service of the person or persons
employed by or associated with the registrant or an investment adviser
of the registrant who are primarily responsible for the day-to-day management
of the registrant's portfolio ("Portfolio Manager"). Also state each Portfolio
Manager's business experience during the past 5 years.


Not applicable to open-end management investment companies.


ITEM 9. PURCHASES OF EQUITY SECURITIES BY CLOSED-END MANAGEMENT
INVESTMENT COMPANY AND AFFILIATED PURCHASERS.

(a) If the registrant is a closed-end management investment company,
in the following tabular format, provide the information specified in
paragraph (b) of this Item with respect to any purchase made by or on
behalf of the registrant or any affiliated purchaser, as defined in
Rule 10b-18(a)(3) under the Exchange Act (17 CFR 240.10b-18(a)(3)), of
shares or other units of any class of the registrant's equity securities
that is registered by the registrant pursuant to Section 12 of the
Exchange Act (15 U.S.C. 781).

Not applicable to open-end management investment companies.


ITEM 10. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS.

Describe any material changes to the procedures by which shareholders
may recommend nominees to the registrant's board of directors, where
those changes were implemented after the registrant last provided
disclosure in response to the requirements of Item 407(c)(2)(iv) of
Regulation S-R(17 CFR 229.407)(as required by Item 22(b)(15))
of Schedule 14A (17 CFR 240.14a-101), or this Item.


There have been no material changes to the procedures by which the
shareholders may recommend nominees to the registrant's board of
directors since the registrant last provided disclosure in response
to the requirements of Item 407(c)(2)(iv) of Regulation S-R of Schedule 14(A)
in its definitive proxy statement, or this item.


ITEM 11. CONTROLS AND PROCEDURES.

(a) Disclose the conclusions of the registrant's principal executive and
principal financials officers, or persons performing similar functions,
regarding the effectiveness of the registrant's disclosure
controls and procedures (as defined in Rule 30a-3(c) under the Act (17 CFR
270.30a-3(c))) as of a date within 90 days of the filing date of the report
that includes the disclosure required by this paragraph,
based on the evaluation of these controls and procedures required by Rule
30a-3(b) under the Act (17 CFR 270.30(a)-3(b) and Rules 13a-15(b) or 15d-15(b)
under the Exchange Act (17 CFR 240.13a-15(b) or 240.15d-15(b)).

The registrant's principal executive officer
and principal financial officer have
concluded that the registrant's disclosure
controls and procedures are effective based
on the evaluation of these controls and
procedures as of a date within 90 days of the
filing date of this report.


(b) Disclose any change in the registrant's internal control over financial
reporting (as defined in Rule 30a-3(d) under the Act (17CFR 270.30a-3(d)) that
occured during the second fiscal quarter of the period covered by this report
that has materially affected, or is reasonably likely to materially affect,
the registrant's internal control over financial reporting.

There were no significant changes in the
registrant's internal control over financial
reporting that occurred during the second
fiscal quarter of the period covered by this
report that have materially affected, or are
reasonably likely to materially affect, the
registrant's internal control over financial
reporting.

The registrant's principal executive officer and principal financial
officer, however, voluntarily are reporting the following information:

In August of 2006 the registrant's investment adviser
enhanced its internal procedures for reporting performance
information required to be included in prospectuses.
Those enhancements involved additional internal controls
over the appropriateness of performance data
generated for this purpose.  Such enhancements were made
following an internal review which identified
prospectuses relating to certain classes of shares of
a limited number of registrants where, inadvertently,
performance information not reflecting the deduction of
applicable sales charges was included. Those prospectuses
were revised, and the revised prospectuses were distributed to
shareholders.

Item 12. Disclosure of Securities Lending Activities for Closed-End
Management Investment Companies.

(a) If the registrant is a closed-end management investment company,
provide the following dollar amounts of income and compensation related
to the securities lending activities of the registrant during its most
recent fiscal year:

N/A

(1) Gross income from securities lending activities;

N/A

(2) All fees and/or compensation for each of the following securities
lending activities and related services: any share of revenue generated
by the securities lending program paid to the securities lending agent(s)
(revenue split); fees paid for cash collateral management services
(including fees deducted from a pooled cash collateral reinvestment
vehicle) that are not included in the revenue split; administrative
fees that are not included in the revenue split; fees for
indemnification that are not included in the revenue split; rebates
paid to borrowers; and any other fees relating to the securities lending
program that are not included in the revenue split, including a description
of those other fees;

N/A

(3) The aggregate fees/compensation disclosed pursuant to paragraph (2); and

N/A

(4) Net income from securities lending activities (i.e., the dollar amount in
paragraph (1) minus the dollar amount in paragraph (3)).

If a fee for a service is included in the revenue split, state that the fee
is included in the revenue split.

N/A

(b) If the registrant is a closed-end management investment company, describe
the services provided to the registrant by the securities lending agent in
the registrants most recent fiscal year.

N/A


ITEM 13. EXHIBITS.

(a) File the exhibits listed below as part of this Form. Letter or number the
exhibits in the sequence indicated.

(1) Any code of ethics, or amendment thereto, that is the subject of the
disclosure required by Item 2, to the extent that the registrant intends to
satisfy the Item 2 requirements through filing of an exhibit.



(2) A separate certification for each principal executive officer and principal
financial officer of the registrant as required by Rule 30a-2(a) under the Act
(17 CFR 270.30a-2(a)) , exactly as set forth below:

Filed herewith.





                                   SIGNATURES

                          [See General Instruction F]


Pursuant to the requirements of the Securities Exchange Act of 1934 and the
Investment Company Act of 1940, the registrant has duly caused this report to be
signed on its behalf by the undersigned, thereunto duly authorized.


(Registrant) Pioneer Series Trust XI


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

Date August 29, 2019


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


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

Date August 29, 2019


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

Date August 29, 2019

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