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, Pioneer Investment 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, 2017 through JUne 30, 2017


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, 2017
--------------------------------------------------------------------------------

                         Ticker Symbols:
                         Class A     PIOTX
                         Class C     PCOTX
                         Class Y     PVFYX

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



                          visit us: amundipioneer.com


Table of Contents


                                                                           

President's Letter                                                             2

Portfolio Management Discussion                                                4

Portfolio Summary                                                             10

Prices and Distributions                                                      11

Performance Update                                                            12

Comparing Ongoing Fund Expenses                                               15

Schedule of Investments                                                       17

Financial Statements                                                          22

Notes to Financial Statements                                                 29

Additional Information                                                        38

Approval of New and Interim Management Agreements                             40

Trustees, Officers and Service Providers                                      48


                        Pioneer Core Equity Fund | Semiannual Report | 6/30/17 1


President's Letter

U.S. markets have continued to generate positive returns during the first
several months of 2017, with so-called "risk" assets, such as equities and
credit-sensitive bonds, posting solid gains. U.S. equities, as measured by the
Standard & Poor's 500 Index, returned slightly more than 6% in the first
calendar quarter of the year and more than 3% for the second quarter.
Meanwhile, high-yield securities have dominated bond market performance thus far
in 2017.

The post-election market momentum we witnessed in the U.S. during the final
weeks of the fourth quarter of 2016 slowed only when oil prices slumped in
March, due to both higher-than-expected inventories and concerns over whether
OPEC (Organization of Petroleum Exporting Countries) would continue its supply
cuts. Not even the Federal Reserve System's (the Fed's) two rate hikes since
March, nor Britain's trigger of Article 50 to begin the "Brexit" process caused
any dramatic sell-off of risk assets. In fact, we are encouraged by the more
hawkish stance of the Fed with regard to interest rates, in light of our view
that current U.S. bond yields do not fairly reflect the prospective levels of
economic activity and inflation. We expect the Fed to continue to tighten
monetary policy, with at least one more rate hike likely to occur before the end
of 2017.

While U.S. gross domestic product (GDP) did slow in the first quarter, ending up
at 1.4% after revisions, the expectation is for GDP growth to pick-up in the
second quarter, with a solid consumer leading the way. It is our view that the
U.S. economy may lead all developed nations in 2017, with GDP growth in excess
of 2% for the full year, even if proposed tax and regulatory reforms are not
passed into law in the near future. We also believe solid domestic employment
figures should continue to support consumption and the housing market, and that
stronger corporate profits and increased government spending may contribute to
economic growth in 2018 and beyond. In addition, as we monitor global Purchasing
Manager Indices (PMIs), we note that their numbers are increasing, which
suggests that growth in global economies is also improving. (PMIs are used to
measure the economic health of the manufacturing sector.)

There are, as always, some risks to our outlook. First, the market already has
priced in a good deal of the Trump economic reform platform, and that could lead
to near-term disappointment if Congressional follow-through does not happen this
year. The future of the Affordable Care Act (ACA) is another potential concern,
as Congressional leaders have, thus far, failed to generate

2 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


enough support to get new health care legislation approved by both houses.
However, if a bill is eventually passed that either eliminates or significantly
alters the ACA, the new law will undoubtedly have an effect on the health care
sector, one of the largest segments of the U.S. economy. Geopolitical risks, of
course, remain a potential headwind, given ongoing strife in the Middle East and
renewed tensions on the Korean Peninsula.

While our current outlook is generally optimistic, conditions can and often do
change, and while passive investment strategies may have a place in one's
overall portfolio, it is our view that all investment decisions are active
choices.

Throughout our history, we have believed in the importance of active management.
The active decisions to invest in equities or fixed-income securities are made
by a team of experienced investment professionals focusing on identifying value
across global markets using proprietary research, careful risk management, and a
long-term perspective. We believe our shareowners can benefit from the
experience and tenure of our investment teams as well as the insights generated
from our extensive research process.

As always, and particularly during times of market uncertainty, we encourage you
to work with your financial advisor to develop an overall investment plan that
addresses both your short- and long-term goals, and to implement such a plan in
a disciplined manner.

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

Sincerely,

/s/ Lisa M. Jones

Lisa M. Jones
Head of the Americas, President and CEO of US
Amundi Pioneer Asset Management USA, Inc.
June 30, 2017

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 | 6/30/17 3


Portfolio Management Discussion | 6/30/17

Important Note: On July 3, 2017, Amundi acquired Pioneer Investments, a group of
asset management companies located throughout the world. Amundi, one of the
world's largest asset managers, is headquartered in Paris, France. As a result
of the transaction, Pioneer Investment Management, Inc., the Fund's investment
adviser, became an indirect wholly owned subsidiary of Amundi and Amundi's
wholly owned subsidiary, Amundi USA, Inc. Prior to July 3, 2017, Pioneer
Investments was owned by Pioneer Global Asset Management S.p.A., a wholly owned
subsidiary of UniCredit S.p.A.

In connection with the transaction, the names of the Fund's investment adviser
and principal underwriter changed. Effective July 3, 2017, the name of Pioneer
Investment Management, Inc. changed to Amundi Pioneer Asset Management, Inc. and
the name of Pioneer Funds Distributor, Inc. changed to Amundi Pioneer
Distributor, Inc.

This transaction does not impact your existing relationship with Pioneer
Investments, your advisor, or the methods you use to communicate with us, as the
investor contact telephone numbers and services you expect will remain the same.
We are excited, however, to be launching a new website representing the combined
company. Come visit us at: www.amundipioneer.com

Domestic stocks generated solid performance over the first half of 2017. 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, 2017. Mr. Sterling, Head of Equity Research,
U.S., a senior vice president, and a portfolio manager at Amundi Pioneer Asset
Management, Inc. ("Amundi Pioneer"), is responsible for day-to-day management of
the Fund's investment portfolio, along with John Peckham, a senior vice
president and a portfolio manager at Amundi Pioneer.

Q   How did the Fund perform during the six-month period ended June 30, 2017?

A   Pioneer Core Equity Fund's Class A shares returned 10.94% at net asset value
    during the six-month period ended June 30, 2017, while the Fund's benchmark,
    the Standard & Poor's 500 Index (the S&P 500), returned 9.33%. During the
    same period, the average return of the 869 mutual funds in Lipper's
    Large-Cap Core Funds category was 8.72%, and the average return of the
    1,459 mutual funds in Morningstar's Large Blend Funds category was 8.65%.

Q   How would you describe the investment environment for equities during the
    six-month period ended June 30, 2017?

A   The equity market moved higher overall and produced healthy returns during
    the period, although at the start of the year, we saw the cyclical rally
    that began before the November 2016 elections start to fade. That rally
    once again picked-up velocity after the victories of Donald J. Trump and the

4 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


    Congressional Republicans in the November elections. We believe cyclical
    stocks moved too far, too fast, however, as equity valuations in early 2017
    implied meaningful corporate profit increases while anticipating certain
    levels of accelerating economic growth. In addition, the stock market surge
    assumed that President Trump and the Republican-controlled Congress could
    reach accords on certain key legislative measures, with health care reform
    (the repeal or replacement of the Affordable Care Act) as well as
    pro-growth fiscal policies such as corporate and income tax cuts and
    regulatory reform near the top of the agenda.

    Some of the biggest sectors and market segments that were post-election
    winners, like energy, banks, and cyclical industrial stocks, soon began to
    lag as economic and legislative realities as well as moderating equity
    valuations set in. For banks, that materialized into a flatter yield curve
    and slower loan growth, while for energy producers, lower oil prices, with
    corporate profits directly affected in each case.

    On the other side of the valuation spectrum, at the start of the period in
    early 2017, the share prices of companies considered secular winners within
    the information technology and consumer sectors (commonly referred to as
    "FAANG" stocks -- Facebook, Apple, Amazon.com, Netflix, and Google) did not
    fully reflect the powerful profit growth, high returns on capital, and
    competitive advantages of those firms, and they ended up leading the market
    over the full six months. Additionally, the fits and starts characterizing
    the Affordable Care Act repeal-and-replace effort by the Republicans had a
    positive effect on stock prices within the health care sector, which
    rebounded with an 18% return during the six-month period, the second-best
    sector performance after information technology.

    The traditionally stable, high-dividend paying* sectors - consumer staples
    and utilities - performed well during the period as the "Trump trade"
    unwound, but gave up most of their outperformance in late May and into June
    as healthy global economic growth became obvious and central banks
    increasingly signaled a commitment to tapering their post-financial-crisis
    monetary stimulus. Combined with historically expensive equity valuations,
    those factors made potentially higher-yielding stocks less attractive.
    Moreover, the announcement of Amazon's acquisition of retail grocer Whole
    Foods stimulated market conjecture about what changes might emerge if
    Amazon were to become an even larger presence in the retail sales and
    distribution area, thus creating a potentially new secular threat to
    consumer staples companies. Telecom services was also a poor-performing
    sector during the period, significantly lagging the S&P 500, as the
    competitive dynamics of the wireless industry has become increasingly
    value-destructive.

*   Dividends are not guaranteed.

                        Pioneer Core Equity Fund | Semiannual Report | 6/30/17 5


Q   What were the principal factors driving the Fund's outperformance of the S&P
    500 Index during the six-month period ended June 30, 2017?

A   Our decision to deeply underweight the portfolio in energy stocks, which we
    thought had reached unattractively high valuations in 2016, was the biggest
    single factor driving the Fund's outperformance of its benchmark during the
    period. Early in the 2017 calendar year, the Fund had almost no energy
    exposure, as we believed then-current stock valuations were too dependent
    on expectations of very high future oil prices. The underweighted position
    turned into a big advantage for the Fund when energy stocks underperformed
    over the six months. Late in the period, we did add ExxonMobil back into
    the portfolio, as it is probably the most conservative stock in the energy
    sector. Nevertheless, we continue to be cautious with regard to adding too
    much exposure to energy companies.

    Excellent stock selection results in the industrials sector also
    contributed significantly to the Fund's benchmark-relative returns, led by
    strong performance from holdings such as CSX and Masco. CSX is an under-
    earning railroad operator that attracted an activist investor, which in
    turn led to the appointment of a new CEO who is a noted turnaround expert
    in the railroad industry. Masco is a manufacturer of architectural coatings
    and household fixtures, with brands that include Behr Paints and Delta
    Faucets.  In addition, our decision to avoid owning shares of General
    Electric aided the Fund's benchmark-relative performance, as the stock
    underperformed due to continued disappointing financial results and
    business-model execution. An overweight to and positive security selection
    results within information technology also contributed positively to the
    Fund's benchmark-relative results during the period, with Apple once again
    turning in excellent performance as the market continues to anticipate its
    next-generation iPhone and as the company's services business continues to
    grow at a rapid pace.

    The Fund also had significant positions in banking institutions, which we
    favored because of their improving prospects in a rising-interest-rate
    environment and the likelihood of some regulatory relief coming from the
    Federal government under the new administration. JPMorgan Chase and PNC
    Financial Services were two of the most notable contributors to the Fund's
    performance among the portfolio's banking holdings. Among other individual
    positions, a large contributor to the Fund's benchmark-relative results was
    Cooper Companies, one of the world's largest manufacturers of daily-wear
    contact lenses. The stock rallied during the period as the competitive
    landscape continued to favor a few dominant companies, including Cooper.

6 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


Q   What investment decisions or individual holdings detracted from the Fund's
    benchmark-relative performance during the six-month period ended June
    30, 2017?

A   The biggest factor holding back benchmark-relative performance during the
    period was the Fund's positioning in the consumer discretionary sector,
    especially in auto parts retailers such as O'Reilly Automotive and Advance
    Auto Parts, both of which operate national store chains. The two stocks
    underperformed as each company experienced unanticipated negative effects
    from relatively mild winter weather and delayed tax refunds. The companies
    also faced the perception of increased competitive challenges from
    e-commerce players, led by Amazon. We retained the Fund's position in
    O'Reilly Automotive, but sold Advance Auto Parts from the portfolio.

    One of the other big detractors from the Fund's benchmark-relative results
    during the period was Synchrony Financial, which had been a positive
    contributor to the Fund's performance in 2016. Synchrony, which is the
    nation's largest provider of private-label credit cards, including store-
    branded cards, underperformed after announcing it was setting aside higher
    reserves for credit losses. We liquidated the Fund's position before the
    end of the period. However, we have retained a portfolio position in
    another underperformer, Sealed Air, which produces specialized packaging
    materials for a variety of industries. Sealed Air disappointed investors
    during the period when it made a sloppy divestiture of an underperforming
    business unit. Nevertheless, we like the prospects for the company's
    remaining business units. Despite the recent setback, we believe Sealed Air
    remains a stable leader and innovator in its two remaining business
    segments -- protein (food) and product-care packaging.

Q   Did the Fund have any investments in derivative securities during the six-
    month period ended June 30, 2017?

A   No, the Fund held no investments in any derivatives during the period.

Q   What is your investment outlook and how have you positioned the Fund's
    portfolio heading into the second half of 2017?

A   We remain optimistic about stocks, as we think valuations should continue to
    be supported by improving corporate profits, which tend to reduce pressure
    on the market's equity risk premium and valuation multiples.  Domestic
    equities, in our opinion, are reasonably priced, especially relative to the
    prices of alternative asset classes, and we do not believe they face any
    imminent threats of a recession, excessive inflation, or rapidly rising
    interest rates. Nonetheless, the inflation outlook, the potential for
    increased levels of global conflict, and political dysfunction in
    Washington continue to be factors that warrant focus with regard to both
    the Fund's positioning and our overall views.

                        Pioneer Core Equity Fund | Semiannual Report | 6/30/17 7


    We believe stock prices of some companies that, in general, do not face
    direct, massive threats from Amazon, have been overly beaten down by
    investors who underestimated the durability of those companies' business
    models. Specifically, those would be: 1) retailers that have unique
    relationships with professionals (for example, auto repair shops,
    professional painters, and contractors), in which time-to-delivery can be
    more important than price, and where complex supply chains are already
    built out; 2) off-price retailers such as TJX and eBay, which have
    extensive business models that are difficult to replicate; or 3) dollar
    stores that cater to low-income consumers, as it is not clear that even
    Amazon can profitably cater to customers whose average shopping trips total
    $15 or less. Nearly 10% of the Fund's total investment portfolio is
    allocated to that theme.

    We like the long-term housing/repair and remodel theme and trend, which we
    believe has a runway for an extended cycle. Birthrates among women more
    than 25 years old have accelerated, and children have always been a
    catalyst for single-family living. Home affordability relative to income
    remains attractive and credit availability is improving. Home-price
    inflation, too, is healthy and a major driver of home improvement spending.
    We have allocated approximately seven percent of the Fund's total
    investment portfolio towards that theme, through positions in Home Depot,
    Sherwin-Williams, and Masco.

    In health care, we believe that managed care is part of any solution to the
    industry's lingering issues in the U.S., and we consider Medicare and
    Medicaid providers to be secular winners. As a result, over three percent
    of the Fund's total investment portfolio is allocated to that segment of
    the health care sector. Moreover, we continue to find value in
    pharmaceutical and biotechnology firms, as we think the market is overly
    discounting drug-development pipelines and undervaluing the sustainability
    of profits from existing drugs.

    We also continue to find opportunities in banks, as valuations within the
    group remain compelling. We believe that interest rates will head higher as
    inflation picks up and global economic growth increases, and the pendulum
    appears to have shifted towards fewer regulations affecting near-term
    profitability. Moreover, we believe the improvement to banks' profitability
    from fewer branches and emerging "fintech" developments is not well
    understood by the market. (Fintech represents computer programs and other
    technology used to support or enable banking and financial services).

    Finally, while we saw value in 2016 in many capital goods and equipment
    companies, we see less value in 2017 and have cut back the portfolio's
    exposure, moving to an underweight position.

8 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


    In selecting securities for the portfolio, we continue to rely on the
    combination of our experienced team of fundamental analysts and a
    proprietary corporate performance and valuation framework grounded in
    business-model economics. We believe those two key components of our
    investment process are critical to the success of the Fund, given the ever-
    evolving secular shifts taking place in nearly every industry.

Please refer to the Schedule of Investments on pages 17-21 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 | 6/30/17 9


Portfolio Summary | 6/30/17

Portfolio Diversification
--------------------------------------------------------------------------------
(As a percentage of total investment portfolio)

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



                                                                        
U.S. Common Stocks                                                         95.4%
International Common Stocks                                                 3.0%
Depository Receipts for International Stocks                                1.1%
U.S. Government Securities                                                  0.5%


Sector Distribution
--------------------------------------------------------------------------------
(As a percentage of equity holdings)

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



                                                                        
Information Technology                                                     23.6%
Consumer Discretionary                                                     16.7%
Financials                                                                 15.1%
Health Care                                                                13.5%
Industrials                                                                 9.6%
Energy                                                                      6.5%
Consumer Staples                                                            5.4%
Materials                                                                   4.8%
Utilities                                                                   3.2%
Telecommunication Services                                                  1.6%


10 Largest Holdings
--------------------------------------------------------------------------------
(As a percentage of equity holdings)*



                                                                        
 1. Apple, Inc.                                                            4.69%
--------------------------------------------------------------------------------
 2. Exxon Mobil Corp.                                                      4.64
--------------------------------------------------------------------------------
 3. Microsoft Corp.                                                        3.61
--------------------------------------------------------------------------------
 4. JPMorgan Chase & Co.                                                   3.47
--------------------------------------------------------------------------------
 5. Comcast Corp.                                                          3.39
--------------------------------------------------------------------------------
 6. Citigroup, Inc.                                                        3.35
--------------------------------------------------------------------------------
 7. American Electric Power Co, Inc.                                       3.25
--------------------------------------------------------------------------------
 8. Alphabet, Inc.                                                         3.18
--------------------------------------------------------------------------------
 9. Visa, Inc.                                                             2.97
--------------------------------------------------------------------------------
10. The Home Depot, Inc.                                                   2.94
--------------------------------------------------------------------------------


*   This list excludes temporary cash investments. 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 listed.

10 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


Prices and Distributions | 6/30/17

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



--------------------------------------------------------------------------------
              Class                  6/30/17                   12/31/16
--------------------------------------------------------------------------------
                                                         
              A                      $ 19.98                   $ 18.01
--------------------------------------------------------------------------------
              C                      $ 17.86                   $ 16.17
--------------------------------------------------------------------------------
              Y                      $ 20.19                   $ 18.18
--------------------------------------------------------------------------------


Distributions per Share: 1/1/17 - 6/30/17
--------------------------------------------------------------------------------



--------------------------------------------------------------------------------
                      Net Investment         Short-Term        Long-Term
         Class            Income            Capital Gains     Capital Gains
--------------------------------------------------------------------------------
                                                       
          A             $  --                 $   --            $    --
--------------------------------------------------------------------------------
          C             $  --                 $   --            $    --
--------------------------------------------------------------------------------
          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 12-14.

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 11


Performance Update | 6/30/17                                      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, 2017)
--------------------------------------------------------------------------------
                 Net            Public
                 Asset          Offering         S&P
                 Value          Price            500
Period           (NAV)          (POP)            Index
--------------------------------------------------------------------------------
                                        
10 years          6.49%          5.86%            7.18%
5 years          12.47          11.14            14.62
1 year           21.12          14.14            17.88
--------------------------------------------------------------------------------


Expense Ratio
(Per prospectus dated May 1, 2017)
--------------------------------------------------------------------------------
                 Gross
--------------------------------------------------------------------------------
              
                 0.94%
--------------------------------------------------------------------------------


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

Value of $10,000 Investment



                       Pioneer Core              S&P 500 Index
                       Equity Fund
                                           
6/07                   $ 9,425                   $10,000
6/08                   $ 8,295                   $ 8,689
6/09                   $ 6,293                   $ 6,413
6/10                   $ 7,097                   $ 7,338
6/11                   $ 9,439                   $ 9,589
6/12                   $ 9,824                   $10,109
6/13                   $11,528                   $12,190
6/14                   $14,269                   $15,187
6/15                   $15,001                   $16,313
6/16                   $14,596                   $16,963
6/17                   $17,678                   $19,996


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

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

NAV results represent the percent change in net asset value per share. 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 | 6/30/17


Performance Update | 6/30/17                                      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, 2017)
--------------------------------------------------------------------------------
                                                 S&P
                 If             If               500
Period           Held           Redeemed         Index
--------------------------------------------------------------------------------
                                        
10 years          5.56%          5.56%            7.18%
5 years          11.49          11.49            14.62
1 year           20.09          20.09            17.88
--------------------------------------------------------------------------------


Expense Ratio
(Per prospectus dated May 1, 2017)
--------------------------------------------------------------------------------
                 Gross
--------------------------------------------------------------------------------
              
                 1.76%
--------------------------------------------------------------------------------


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

Value of $10,000 Investment



                       Pioneer Core              S&P 500 Index
                       Equity Fund
                                           
6/07                   $10,000                   $10,000
6/08                   $ 8,740                   $ 8,689
6/09                   $ 6,569                   $ 6,413
6/10                   $ 7,339                   $ 7,338
6/11                   $ 9,667                   $ 9,589
6/12                   $ 9,973                   $10,109
6/13                   $11,585                   $12,190
6/14                   $14,215                   $15,187
6/15                   $14,816                   $16,313
6/16                   $14,307                   $16,963
6/17                   $17,182                   $19,996


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

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

Class C shares held for less than one year are also subject to a 1% contingent
deferred sales charge (CDSC). If you paid a 1% sales charge, your returns would
be lower than those shown above. "If Held" results represent the percent change
in net asset value per share. 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 | 6/30/17 13


Performance Update | 6/30/17                                      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, 2017)
--------------------------------------------------------------------------------
                 Net
                 Asset          S&P
                 Value          500
Period           (NAV)          Index
--------------------------------------------------------------------------------
                          
10 years          6.81%          7.18%
5 years          12.80          14.62
1 year           21.40          17.88
--------------------------------------------------------------------------------


Expense Ratio
(Per prospectus dated May 1, 2017)
--------------------------------------------------------------------------------
                 Gross
--------------------------------------------------------------------------------
              
                 0.63%
--------------------------------------------------------------------------------


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

Value of $5 Million Investment



                       Pioneer Core              S&P 500 Index
                       Equity Fund
                                           
6/07                   $5,000,000                $5,000,000
6/08                   $4,419,093                $4,344,346
6/09                   $3,367,781                $3,206,268
6/10                   $3,806,288                $3,668,890
6/11                   $5,073,608                $4,794,496
6/12                   $5,290,960                $5,054,739
6/13                   $6,224,310                $6,095,190
6/14                   $7,729,171                $7,593,575
6/15                   $8,151,232                $8,156,631
6/16                   $7,959,099                $8,481,654
6/17                   $9,662,377                $9,998,237


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

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

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

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

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

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

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

14 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


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, 2017, through June 30, 2017.



--------------------------------------------------------------------------------
 Share Class                           A               C                   Y
--------------------------------------------------------------------------------
                                                               
Beginning Account Value            $1,000.00       $1,000.00           $1,000.00
on 1/1/17
--------------------------------------------------------------------------------
Ending Account Value               $1,109.40       $1,104.50           $1,110.60
on 6/30/17
--------------------------------------------------------------------------------
Expenses Paid                      $    4.65       $    8.97           $    3.30
During Period*
--------------------------------------------------------------------------------


*   Expenses are equal to the Fund's annualized net expense ratio of 0.89%,
    1.72% and 0.63% for Class A, Class C and Class Y shares, 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 | 6/30/17 15


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, 2017, through June 30, 2017.



--------------------------------------------------------------------------------
 Share Class                           A               C                   Y
--------------------------------------------------------------------------------
                                                              
Beginning Account Value            $1,000.00       $1,000.00           $1,000.00
on 1/1/17
--------------------------------------------------------------------------------
Ending Account Value               $1,020.38       $1,016.27           $1,021.67
on 6/30/17
--------------------------------------------------------------------------------
Expenses Paid                      $    4.46       $    8.60           $    3.16
During Period*
--------------------------------------------------------------------------------


*   Expenses are equal to the Fund's annualized net expense ratio of 0.89%,
    1.72% and 0.63% for Class A, Class C and Class Y shares, respectively,
    multiplied by the average account value over the period, multiplied by
    181/365 (to reflect the one-half year period).

16 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


Schedule of Investments | 6/30/17 (unaudited)



----------------------------------------------------------------------------------------
Shares                                                                    Value
----------------------------------------------------------------------------------------
                                                                    
             COMMON STOCKS -- 98.3%
             ENERGY -- 6.5%
             Integrated Oil & Gas -- 4.6%
   896,372   Exxon Mobil Corp.                                            $   72,364,112
----------------------------------------------------------------------------------------
             Oil & Gas Exploration & Production -- 1.9%
   436,391   Cabot Oil & Gas Corp.                                        $   10,944,686
   213,038   EOG Resources, Inc.                                              19,284,200
                                                                          --------------
                                                                          $   30,228,886
                                                                          --------------
             Total Energy                                                 $  102,592,998
----------------------------------------------------------------------------------------
             MATERIALS -- 4.8%
             Fertilizers & Agricultural Chemicals -- 1.4%
   155,923   Agrium, Inc.                                                 $   14,109,472
   269,854   CF Industries Holdings, Inc.                                      7,545,118
                                                                          --------------
                                                                          $   21,654,590
----------------------------------------------------------------------------------------
             Specialty Chemicals -- 1.8%
    80,648   The Sherwin-Williams Co.                                     $   28,304,222
----------------------------------------------------------------------------------------
             Paper Packaging -- 1.6%
   573,834   Sealed Air Corp.                                             $   25,684,810
                                                                          --------------
             Total Materials                                              $   75,643,622
----------------------------------------------------------------------------------------
             CAPITAL GOODS -- 6.6%
             Aerospace & Defense -- 2.3%
   224,973   Raytheon Co.                                                 $   36,328,640
----------------------------------------------------------------------------------------
             Building Products -- 2.2%
   916,875   Masco Corp.                                                  $   35,033,794
----------------------------------------------------------------------------------------
             Industrial Conglomerates -- 1.0%
   156,352   Carlisle Companies, Inc.                                     $   14,915,981
----------------------------------------------------------------------------------------
             Trading Companies & Distributors -- 1.1%
   159,138   United Rentals, Inc.*                                        $   17,936,444
                                                                          --------------
             Total Capital Goods                                          $  104,214,859
----------------------------------------------------------------------------------------
             TRANSPORTATION -- 2.9%
             Air Freight & Logistics -- 1.9%
   271,502   United Parcel Service, Inc. (Class B)                        $   30,025,406
----------------------------------------------------------------------------------------
             Trucking -- 1.0%
   177,504   JB Hunt Transport Services, Inc.                             $   16,220,316
                                                                          --------------
             Total Transportation                                         $   46,245,722
----------------------------------------------------------------------------------------
             AUTOMOBILES & COMPONENTS -- 1.1%
             Auto Parts & Equipment -- 1.1%
   198,609   Delphi Automotive Plc                                        $   17,408,079
                                                                          --------------
             Total Automobiles & Components                               $   17,408,079
----------------------------------------------------------------------------------------


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

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 17


Schedule of Investments | 6/30/17 (unaudited) (continued)



----------------------------------------------------------------------------------------
Shares                                                                    Value
----------------------------------------------------------------------------------------
                                                                    
             CONSUMER DURABLES & APPAREL -- 1.4%
             Footwear -- 1.4%
   379,651   NIKE, Inc. (Class B)                                         $   22,399,409
                                                                          --------------
             Total Consumer Durables & Apparel                            $   22,399,409
----------------------------------------------------------------------------------------
             CONSUMER SERVICES -- 2.8%
             Restaurants -- 2.8%
   750,580   Starbucks Corp.                                              $   43,766,320
                                                                          --------------
             Total Consumer Services                                      $   43,766,320
----------------------------------------------------------------------------------------
             MEDIA -- 3.3%
             Cable & Satellite -- 3.3%
 1,359,156   Comcast Corp.                                                $   52,898,352
                                                                          --------------
             Total Media                                                  $   52,898,352
----------------------------------------------------------------------------------------
             RETAILING -- 7.9%
             General Merchandise Stores -- 2.1%
   457,605   Dollar General Corp.*                                        $   32,988,744
----------------------------------------------------------------------------------------
             Apparel Retail -- 1.1%
   242,821   The TJX Companies, Inc.                                      $   17,524,392
----------------------------------------------------------------------------------------
             Home Improvement Retail -- 2.9%
   299,245   The Home Depot, Inc.                                         $   45,904,183
----------------------------------------------------------------------------------------
             Automotive Retail -- 1.8%
   129,959   O'Reilly Automotive, Inc.*                                   $   28,427,232
                                                                          --------------
             Total Retailing                                              $  124,844,551
----------------------------------------------------------------------------------------
             FOOD & STAPLES RETAILING -- 1.4%
             Drug Retail -- 1.4%
   283,355   CVS Health Corp.                                             $   22,798,743
                                                                          --------------
             Total Food & Staples Retailing                               $   22,798,743
----------------------------------------------------------------------------------------
             FOOD, BEVERAGE & TOBACCO -- 3.9%
             Packaged Foods & Meats -- 3.9%
   233,744   McCormick & Co., Inc.                                        $   22,792,377
   367,608   The Hershey Co.                                                  39,470,071
                                                                          --------------
                                                                          $   62,262,448
                                                                          --------------
             Total Food, Beverage & Tobacco                               $   62,262,448
----------------------------------------------------------------------------------------
             HEALTH CARE EQUIPMENT & SERVICES -- 5.1%
             Health Care Supplies -- 2.0%
   132,220   The Cooper Companies, Inc.                                   $   31,656,112
----------------------------------------------------------------------------------------


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

18 Pioneer Core Equity Fund | Semiannual Report | 6/30/17




----------------------------------------------------------------------------------------
Shares                                                                    Value
----------------------------------------------------------------------------------------
                                                                    
             Managed Health Care -- 3.1%
   336,795   Centene Corp.*                                               $   26,903,185
    94,109   Humana, Inc.                                                     22,644,508
                                                                          --------------
                                                                          $   49,547,693
                                                                          --------------
             Total Health Care Equipment & Services                       $   81,203,805
----------------------------------------------------------------------------------------
             PHARMACEUTICALS, BIOTECHNOLOGY & LIFE SCIENCES -- 8.3%
             Biotechnology -- 4.4%
   196,549   Celgene Corp.*                                               $   25,525,819
   434,755   Gilead Sciences, Inc.*                                           30,771,959
   100,974   Vertex Pharmaceuticals, Inc.*                                    13,012,519
                                                                          --------------
                                                                          $   69,310,297
----------------------------------------------------------------------------------------
             Pharmaceuticals -- 3.9%
   100,943   Jazz Pharmaceuticals Plc*                                    $   15,696,636
 1,349,681   Pfizer, Inc.                                                     45,335,785
                                                                          --------------
                                                                          $   61,032,421
                                                                          --------------
             Total Pharmaceuticals, Biotechnology & Life Sciences         $  130,342,718
----------------------------------------------------------------------------------------
             BANKS -- 9.2%
             Diversified Banks -- 6.8%
   780,844   Citigroup, Inc.                                              $   52,222,847
   592,097   JPMorgan Chase & Co.                                             54,117,666
                                                                          --------------
                                                                          $  106,340,513
----------------------------------------------------------------------------------------
             Regional Banks -- 2.4%
   307,349   The PNC Financial Services Group, Inc.                       $   38,378,670
                                                                          --------------
             Total Banks                                                  $  144,719,183
----------------------------------------------------------------------------------------
             DIVERSIFIED FINANCIALS -- 3.7%
             Specialized Finance -- 1.2%
   280,844   Intercontinental Exchange, Inc.                              $   18,513,236
----------------------------------------------------------------------------------------
             Asset Management & Custody Banks -- 1.2%
    46,593   BlackRock, Inc.                                              $   19,681,349
----------------------------------------------------------------------------------------
             Investment Banking & Brokerage -- 1.3%
   463,941   The Charles Schwab Corp.                                     $   19,930,905
                                                                          --------------
             Total Diversified Financials                                 $   58,125,490
----------------------------------------------------------------------------------------
             INSURANCE -- 1.8%
             Insurance Brokers -- 1.8%
   356,740   Marsh & McLennan Companies, Inc.                             $   27,811,450
                                                                          --------------
             Total Insurance                                              $   27,811,450
----------------------------------------------------------------------------------------


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

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 19


Schedule of Investments | 6/30/17 (unaudited) (continued)



----------------------------------------------------------------------------------------
Shares                                                                    Value
----------------------------------------------------------------------------------------
                                                                    
             SOFTWARE & SERVICES -- 13.1%
             Internet Software & Services -- 5.3%
    53,283   Alphabet, Inc. (Class A)                                     $   49,536,139
     7,147   Alphabet, Inc. (Class C)                                          6,494,693
   784,725   eBay, Inc.*                                                      27,402,597
                                                                          --------------
                                                                          $   83,433,429
----------------------------------------------------------------------------------------
             IT Consulting & Other Services -- 1.3%
   313,878   Cognizant Technology Solutions Corp.*                        $   20,841,499
----------------------------------------------------------------------------------------
             Data Processing & Outsourced Services -- 2.9%
   494,483   Visa, Inc.                                                   $   46,372,616
----------------------------------------------------------------------------------------
             Systems Software -- 3.6%
   816,859   Microsoft Corp.                                              $   56,306,091
                                                                          --------------
             Total Software & Services                                    $  206,953,635
----------------------------------------------------------------------------------------
             TECHNOLOGY HARDWARE & EQUIPMENT -- 8.0%
             Communications Equipment -- 2.2%
 1,125,941   Cisco Systems, Inc.                                          $   35,241,953
----------------------------------------------------------------------------------------
             Computer Storage & Peripherals -- 4.6%
   508,376   Apple, Inc.                                                  $   73,216,312
----------------------------------------------------------------------------------------
             Technology Distributors -- 1.2%
   293,533   CDW Corp./DE*                                                $   18,354,618
                                                                          --------------
             Total Technology Hardware & Equipment                        $  126,812,883
----------------------------------------------------------------------------------------
             SEMICONDUCTORS & SEMICONDUCTOR EQUIPMENT -- 2.3%
             Semiconductors -- 2.3%
   622,084   Micron Technology, Inc.*                                     $   18,575,428
   493,260   Taiwan Semiconductor Manufacturing Co., Ltd. (A.D.R.)            17,244,370
                                                                          --------------
                                                                          $   35,819,798
                                                                          --------------
             Total Semiconductors & Semiconductor Equipment               $   35,819,798
----------------------------------------------------------------------------------------
             TELECOMMUNICATION SERVICES -- 1.0%
             Integrated Telecommunication Services -- 1.0%
   678,693   CenturyLink, Inc.                                            $   16,207,189
                                                                          --------------
             Total Telecommunication Services                             $   16,207,189
----------------------------------------------------------------------------------------
             UTILITIES -- 3.2%
             Electric Utilities -- 3.2%
   730,706   American Electric Power Co., Inc.                            $   50,762,145
                                                                          --------------
             Total Utilities                                              $   50,762,145
----------------------------------------------------------------------------------------
             TOTAL COMMON STOCKS
             (Cost $1,330,476,807)                                        $1,553,833,399
----------------------------------------------------------------------------------------


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

20 Pioneer Core Equity Fund | Semiannual Report | 6/30/17




----------------------------------------------------------------------------------------
Principal
Amount ($)                                                                Value
----------------------------------------------------------------------------------------
                                                                    
             U.S. GOVERNMENT AND AGENCY OBLIGATION -- 0.4%
 5,930,000   U.S. Treasury Bill 7/6/17 (b)                                $    5,929,626
----------------------------------------------------------------------------------------
             TOTAL U.S. GOVERNMENT AND AGENCY OBLIGATION
             (Cost $5,929,321)                                            $    5,929,626
----------------------------------------------------------------------------------------
             TOTAL INVESTMENT IN SECURITIES -- 98.7%
             (Cost $1,336,406,128) (a)                                    $1,559,763,025
----------------------------------------------------------------------------------------
             OTHER ASSETS & LIABILITIES -- 1.3%                           $   19,931,524
----------------------------------------------------------------------------------------
             TOTAL NET ASSETS -- 100.0%                                   $1,579,694,549
========================================================================================


*            Non-income producing security.

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

(a)          At June 30, 2017, the net unrealized appreciation on investments
             based on cost for federal income tax purposes of $1,338,219,578 was
             as follows:



                                                                                    
             Aggregate gross unrealized appreciation for all investments in which
              there is an excess of value over tax cost                                $ 231,684,073
             Aggregate gross unrealized depreciation for all investments in which
              there is an excess of tax cost over value                                  (10,140,626)
                                                                                       -------------
              Net unrealized appreciation                                              $ 221,543,447
                                                                                       =============


Purchases and sales of securities (excluding temporary cash investments) for the
six months ended June 30, 2017, aggregated $758,787,717 and $814,709,715,
respectively.

The Fund is permitted to engage in purchase and sale transactions ("cross
trades") with certain Funds and accounts for which Amundi Pioneer Asset
Management, Inc., (Amundi Pioneer) formerly Pioneer Investment Management, Inc.
(PIM), 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, 2017, the Fund did not
engage in cross trade activity.

Various inputs are used in determining the value of the Fund's investments.
These inputs are summarized in the three broad levels listed 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
              risk, 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, 2017, in valuing
the Fund's investments:



-------------------------------------------------------------------------------------------------
                              Level 1               Level 2         Level 3        Total
-------------------------------------------------------------------------------------------------
                                                                       
Common Stocks                 $ 1,553,833,399       $       --      $ --           $1,553,833,399
U.S. Government and
 Agency Obligation                         --        5,929,626        --                5,929,626
-------------------------------------------------------------------------------------------------
 Total                        $ 1,553,833,399       $5,929,626      $ --           $1,559,763,025
=================================================================================================


During the six months ended June 30, 2017, 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 | 6/30/17 21


Statement of Assets and Liabilities | 6/30/17 (unaudited)



                                                                          
ASSETS:
  Investment in securities (cost $1,336,406,128)                             $ 1,559,763,025
  Cash                                                                             4,337,776
  Receivables --
     Investment securities sold                                                   42,613,152
     Fund shares sold                                                                214,531
     Dividends                                                                     1,078,473
--------------------------------------------------------------------------------------------
        Total assets                                                         $ 1,608,006,957
============================================================================================
LIABILITIES:
   Payables --
      Investment securities purchased                                        $    26,280,192
      Fund shares repurchased                                                      1,233,208
      Distributions                                                                   67,918
      Trustee fees                                                                     2,525
   Due to affiliates                                                                 335,022
   Accrued expenses                                                                  393,543
--------------------------------------------------------------------------------------------
         Total liabilities                                                   $    28,312,408
============================================================================================
NET ASSETS:
  Paid-in capital                                                            $ 1,277,576,531
  Undistributed net investment income                                              7,065,944
  Accumulated net realized gain on investments and futures contracts              71,695,177
  Net unrealized appreciation on investments                                     223,356,897
--------------------------------------------------------------------------------------------
        Net assets                                                           $ 1,579,694,549
============================================================================================
NET ASSET VALUE PER SHARE:
(No par value, unlimited number of shares authorized)
   Class A (based on $1,518,225,825/75,997,229 shares)                       $         19.98
   Class C (based on $13,491,815/755,596 shares)                             $         17.86
   Class Y (based on $47,976,909/2,376,316 shares)                           $         20.19
MAXIMUM OFFERING PRICE:
   Class A ($19.98 (divided by) 94.25%)                                      $         21.20
============================================================================================


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

22 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


Statement of Operations (unaudited)

For the Six Months Ended 6/30/17



                                                                             
INVESTMENT INCOME:
   Dividends (net of withholding tax of $155,470)                 $ 13,547,994
   Interest                                                             84,515
-----------------------------------------------------------------------------------------------
         Total investment income                                                   $ 13,632,509
-----------------------------------------------------------------------------------------------
EXPENSES:
  Management fees                                                 $  3,867,523
  Transfer agent fees
     Class A                                                           469,702
     Class C                                                             8,431
     Class Y                                                            15,989
  Distribution fees
     Class A                                                         1,857,891
     Class C                                                            68,971
  Shareholder communications expense                                   117,354
  Administrative expense                                               308,128
  Custodian fees                                                        15,947
  Registration fees                                                     27,508
  Professional fees                                                     33,381
  Printing expense                                                      14,047
  Fees and expenses of nonaffiliated Trustees                           39,528
  Miscellaneous                                                         44,066
-----------------------------------------------------------------------------------------------
     Total expenses                                                                $  6,888,466
-----------------------------------------------------------------------------------------------
         Net investment income                                                     $  6,744,043
-----------------------------------------------------------------------------------------------
REALIZED AND UNREALIZED GAIN (LOSS) ON
INVESTMENTS AND FUTURES CONTRACTS:
Net realized gain (loss) on:
   Investments                                                    $111,627,089
   Futures contracts                                                   (99,315)    $111,527,774
-----------------------------------------------------------------------------------------------
Change in net unrealized appreciation (depreciation)
   on investments                                                                  $ 41,826,433
-----------------------------------------------------------------------------------------------
   Net realized and unrealized gain (loss) on investments
      and futures contracts                                                        $153,354,207
-----------------------------------------------------------------------------------------------
   Net increase in net assets resulting from operations                            $160,098,250
===============================================================================================


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

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 23


Statements of Changes in Net Assets



----------------------------------------------------------------------------------------------------
                                                               Six Months
                                                               Ended
                                                               6/30/17             Year Ended
                                                               (unaudited)         12/31/16
----------------------------------------------------------------------------------------------------
                                                                             
FROM OPERATIONS:
Net investment income (loss)                                   $     6,744,043     $     16,856,119
Net realized gain (loss) on investments and
  futures contracts                                                111,527,774           47,430,069
Change in net unrealized appreciation (depreciation)
  on investments                                                    41,826,433           53,203,971
----------------------------------------------------------------------------------------------------
      Net increase (decrease) in net assets resulting
          from operations                                      $   160,098,250     $    117,490,159
----------------------------------------------------------------------------------------------------
DISTRIBUTIONS TO SHAREOWNERS:
Net investment income:
      Class A ($0.00 and $0.20 per share, respectively)        $            --     $    (16,068,920)
      Class C ($0.00 and $0.09 per share, respectively)                     --              (69,203)
      Class Y ($0.00 and $0.25 per share, respectively)                     --             (623,537)
----------------------------------------------------------------------------------------------------
         Total distributions to shareowners                    $            --     $    (16,761,660)
----------------------------------------------------------------------------------------------------
FROM FUND SHARE TRANSACTIONS:
Net proceeds from sale of shares                               $    17,849,385     $     25,299,938
Reinvestment of distributions                                               --           15,467,606
Cost of shares repurchased                                         (92,391,981)        (174,484,709)
----------------------------------------------------------------------------------------------------
      Net decrease in net assets resulting from
         Fund share transactions                               $   (74,542,596)    $   (133,717,165)
----------------------------------------------------------------------------------------------------
      Net increase (decrease) in net assets                    $    85,555,654     $    (32,988,666)
NET ASSETS:
Beginning of period                                            $ 1,494,138,895     $  1,527,127,561
----------------------------------------------------------------------------------------------------
End of period                                                  $ 1,579,694,549     $  1,494,138,895
====================================================================================================
Undistributed net investment income                            $     7,065,944     $        321,901
====================================================================================================


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

24 Pioneer Core Equity Fund | Semiannual Report | 6/30/17




---------------------------------------------------------------------------------------------
                                 Six Months    Six Months
                                 Ended         Ended
                                 6/30/17       6/30/17          Year Ended    Year Ended
                                 Shares        Amount           12/31/16      12/31/16
                                 (unaudited)   (unaudited)      Shares        Amount
---------------------------------------------------------------------------------------------
                                                                  
Class A
Shares sold                         530,526    $ 10,234,729        976,643     $  16,421,975
Reinvestment of distributions            --              --        835,056        15,256,426
Less shares repurchased          (4,265,753)    (82,018,269)    (8,452,628)     (142,378,598)
---------------------------------------------------------------------------------------------
      Net decrease               (3,735,227)   $(71,783,540)    (6,640,929)    $(110,700,197)
=============================================================================================
Class C
Shares sold                          95,178    $  1,623,458        163,251     $   2,510,542
Reinvestment of distributions            --              --          3,831            62,819
Less shares repurchased            (144,721)     (2,519,931)      (295,427)       (4,379,785)
---------------------------------------------------------------------------------------------
      Net decrease                  (49,543)   $   (896,473)      (128,345)    $  (1,806,424)
=============================================================================================
Class Y
Shares sold                         307,957    $  5,991,198        368,360     $   6,367,421
Reinvestment of distributions            --              --          8,046           148,361
Less shares repurchased            (402,107)     (7,853,781)    (1,576,444)      (27,726,326)
---------------------------------------------------------------------------------------------
      Net decrease                  (94,150)   $ (1,862,583)    (1,200,038)    $ (21,210,544)
=============================================================================================


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

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 25


Financial Highlights



----------------------------------------------------------------------------------------------------------------------------------
                                              Six Months
                                              Ended             Year          Year            Year         Year        Year
                                              6/30/17           Ended         Ended           Ended        Ended       Ended
                                              (unaudited)       12/31/16      12/31/15        12/31/14     12/31/13(a) 12/31/12(a)
----------------------------------------------------------------------------------------------------------------------------------
                                                                                                     
Class A
Net asset value, beginning of period          $    18.01        $    16.80    $    17.18      $    15.70   $    12.06  $ 10.61
----------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment
     operations:
   Net investment income (loss)               $     0.08(b)     $     0.19(b) $     0.13(b)   $     0.18   $     0.10  $  0.08
   Net realized and unrealized gain (loss)
     on investments                                 1.89              1.22         (0.39)           1.46         3.63     1.45
----------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment
     operations                               $     1.97        $     1.41    $    (0.26)     $     1.64   $     3.73  $  1.53
----------------------------------------------------------------------------------------------------------------------------------
Distribution to shareowners:
   Net investment income                      $       --        $    (0.20)   $    (0.12)     $    (0.16)  $    (0.09) $ (0.08)
----------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value    $     1.97        $     1.21    $    (0.38)     $     1.48   $     3.64  $  1.45
----------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                $    19.98        $    18.01    $    16.80      $    17.18   $    15.70  $ 12.06
==================================================================================================================================
Total return*                                      10.94%             8.39%        (1.49)%(d)      10.44%       31.02%   14.51%
Ratio of net expenses to average net
   assets (c)                                       0.89%**           0.94%         0.93%           0.94%        0.99%    1.25%
Ratio of net investment income (loss) to
   average net assets                               0.87%**           1.15%         0.75%           1.03%        0.70%    0.76%
Portfolio turnover rate                              101%**             80%          100%             57%          67%      59%
Net assets, end of period (in thousands)      $1,518,226        $1,436,208    $1,450,815      $1,605,301   $1,585,294  $23,907
Ratios with no waiver of fees and assumption
   of expenses by Amundi Pioneer formerly
   PIM and no reduction for fees paid
   indirectly:
   Total expenses to average net assets (c)         0.89%**           0.94%         0.93%           0.94%        0.99%    1.59%
   Net investment income (loss) to average
     net assets                                     0.87%**           1.15%         0.75%           1.03%        0.70%    0.42%
==================================================================================================================================


*   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.

**  Annualized.

(a) The Fund acquired the assets and liabilities of Pioneer Research Fund (the
    "predecessor fund") on June 7, 2013 (the "reorganization"). As a result of
    the reorganization, the predecessor fund's performance and financial history
    became the performance and financial history of the Fund. Historical
    per-share amounts prior to June 7, 2013 have been adjusted to reflect the
    conversion ratio used to align the net asset values of the predecessor fund
    with those of the Fund.

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

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

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

+   Amount rounds to less than 0.01%.

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

26 Pioneer Core Equity Fund | Semiannual Report | 6/30/17




----------------------------------------------------------------------------------------------------------------------------------
                                              Six Months
                                              Ended             Year          Year            Year         Year        Year
                                              6/30/17           Ended         Ended           Ended        Ended       Ended
                                              (unaudited)       12/31/16      12/31/15        12/31/14     12/31/13(a) 12/31/12(a)
----------------------------------------------------------------------------------------------------------------------------------
                                                                                                     
Class C
Net asset value, beginning of period          $ 16.17           $ 15.11       $ 15.48         $  14.19     $ 10.93     $  9.65
----------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment
   operations:
   Net investment income (loss)               $ (0.00)(b)(c)(f) $  0.05(b)    $ (0.01)(b)(c)  $   0.02     $ (0.02)(c) $ (0.01)(c)
   Net realized and unrealized gain (loss)
     on investments                              1.69              1.10         (0.35)            1.33        3.28        1.30
----------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment
   operations                                 $  1.69           $  1.15       $ (0.36)        $   1.35     $  3.26     $  1.29
----------------------------------------------------------------------------------------------------------------------------------
Distribution to shareowners:
   Net investment income                      $    --           $ (0.09)      $ (0.01)        $  (0.06)    $    --     $ (0.01)
----------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value    $  1.69           $  1.06       $ (0.37)        $   1.29     $  3.26     $  1.28
----------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                $ 17.86           $ 16.17       $ 15.11         $  15.48     $ 14.19     $ 10.93
==================================================================================================================================
Total return*                                   10.45%             7.58%        (2.34)%(e)        9.52%      29.81%      13.37%
Ratio of net expenses to average net
   assets (d)                                    1.72%**           1.76%         1.74%            1.81%       1.92%       2.15%
Ratio of net investment income (loss) to
   average net assets                            0.05%**           0.33%        (0.06)%           0.14%      (0.17)%     (0.14)%
Portfolio turnover rate                           101%**             80%          100%              57%         67%         59%
Net assets, end of period (in thousands)      $13,492           $13,016       $14,106         $ 13,848     $11,112     $ 3,695
Ratios with no waiver of fees and assumption
   of expenses by Amundi Pioneer formerly PIM
   and no reduction for fees paid indirectly:
   Total expenses to average net assets (d)      1.72%**           1.76%         1.74%            1.81%       1.92%       2.31%
   Net investment income (loss) to average
     net assets                                 0.05%**            0.33%        (0.06)%           0.14%      (0.17)%     (0.30)%
==================================================================================================================================


*   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.

**  Annualized.

(a) The Fund acquired the assets and liabilities of Pioneer Research Fund (the
    "predecessor fund") on June 7, 2013 (the "reorganization"). As a result of
    the reorganization, the predecessor fund's performance and financial history
    became the performance and financial history of the Fund. Historical
    per-share amounts prior to June 7, 2013 have been adjusted to reflect the
    conversion ratio used to align the net asset values of the predecessor fund
    with those of the Fund.

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

(c) 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 shares.

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

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

(f) Amount rounds to less than $0.01 or $(0.01) per share.

+   Amount rounds to less than 0.01%.

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

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 27


Financial Highlights (continued)



----------------------------------------------------------------------------------------------------------------------------------
                                              Six Months
                                              Ended             Year          Year            Year         Year        Year
                                              6/30/17           Ended         Ended           Ended        Ended       Ended
                                              (unaudited)       12/31/16      12/31/15        12/31/14     12/31/13(a) 12/31/12(a)
----------------------------------------------------------------------------------------------------------------------------------
                                                                                                     
Class Y
Net asset value, beginning of period          $   18.18         $ 16.95       $ 17.34         $ 15.85      $ 12.17     $ 10.69
----------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment
   operations:
   Net investment income (loss)               $    0.11(b)      $  0.25(b)    $  0.19(b)      $  0.20      $  0.14     $  0.11
   Net realized and unrealized gain (loss)
     on investments                                1.90            1.23         (0.40)           1.51         3.68        1.47
----------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment
   operations                                 $    2.01         $  1.48       $ (0.21)        $  1.71      $  3.82     $  1.58
----------------------------------------------------------------------------------------------------------------------------------
Distribution to shareowners:
   Net investment income                      $      --         $ (0.25)      $ (0.18)        $ (0.22)     $ (0.14)    $ (0.10)
----------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value    $    2.01         $  1.23       $ (0.39)        $  1.49      $  3.68     $  1.48
----------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                $   20.19         $ 18.18       $ 16.95         $ 17.34      $ 15.85     $ 12.17
==================================================================================================================================
Total return*                                     11.06%           8.73%        (1.21)%(d)      10.75%       31.49%      14.81%
Ratio of net expenses to average net
   assets (c)                                      0.63%**         0.63%         0.62%           0.63%        0.75%       1.02%
Ratio of net investment income (loss) to
   average net assets                              1.13%**         1.47%         1.07%           1.37%        1.01%       0.97%
Portfolio turnover rate                             101%**           80%          100%             57%          67%         59%
Net assets, end of period (in thousands)      $  47,977         $44,915       $62,206         $66,424      $59,812     $33,875
==================================================================================================================================


*   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.

**  Annualized.

(a) The Fund acquired the assets and liabilities of Pioneer Research Fund (the
    "predecessor fund") on June 7, 2013 (the "reorganization"). As a result of
    the reorganization, the predecessor fund's performance and financial history
    became the performance and financial history of the Fund. Historical
    per-share amounts prior to June 7, 2013 have been adjusted to reflect the
    conversion ratio used to align the net asset values of the predecessor fund
    with those of the Fund.

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

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

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

+   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 | 6/30/17


Notes to Financial Statements | 6/30/17 (unaudited)

1.  Organization and Significant Accounting Policies

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

The Fund offers three classes of shares designated as Class A, Class C and Class
Y shares. 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 shareholder approval. Under per-share voting, each share
of a class of the Fund is entitled to one vote. Under dollar-weighted voting, a
shareholder's voting power is determined not by the number of shares owned, but
by the dollar value of the shares on the record date. Each share class has
exclusive voting rights with respect to matters affecting only that class,
including with respect to the distribution plan for that class. There is no
distribution plan for Class Y shares.

On July 3, 2017, Amundi acquired Pioneer Investments, a group of asset
management companies located throughout the world. Amundi, one of the world's
largest asset managers, is headquartered in Paris, France. As a result of the
transaction, Pioneer Investment Management, Inc., the Fund's investment adviser,
became an indirect wholly owned subsidiary of Amundi and Amundi's wholly owned
subsidiary, Amundi USA, Inc. Prior to July 3, 2017, Pioneer Investments was
owned by Pioneer Global Asset Management S.p.A., a wholly owned subsidiary of
UniCredit S.p.A.

In connection with the transaction, the names of the Fund's investment adviser
and principal underwriter changed. Effective July 3, 2017, the name of Pioneer
Investment Management, Inc. changed to Amundi Pioneer Asset Management, Inc. and
the name of Pioneer Funds Distributor, Inc. changed to Amundi Pioneer
Distributor, Inc.

The Fund's financial statements have been prepared in conformity with U.S.
generally accepted accounting principles (U.S. GAAP) that require the management
of the Fund to make estimates and assumptions that affect the reported amounts
of assets and liabilities, the disclosure of contingent assets

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 29


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 Fund is an investment company and follows investment company accounting and
reporting guidance under U.S. GAAP. The following is a summary of significant
accounting policies followed by the Fund in the preparation of its financial
statements:

A.  Security Valuation

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

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

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

    Securities for which independent pricing services or broker-dealers are
    unable to supply prices or for which market prices and/or quotations are
    not readily available or are considered to be unreliable are valued by a
    fair valuation team comprised of certain personnel of Amundi Pioneer Asset
    Management, Inc., (Amundi Pioneer), formerly Pioneer Investment Management,
    Inc. (PIM), the Fund's investment adviser, pursuant to procedures adopted
    by the Fund's Board of Trustees. Amundi Pioneer's, formerly PIM's, fair
    valuation team uses fair value methods approved by the Valuation Committee
    of the Board of Trustees. Amundi Pioneer's, formerly PIM'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.

30 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


    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, 2017, there were no securities valued using fair value methods
    (other than securities valued using prices supplied by independent pricing
    services).

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.

    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 in 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.

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 31


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, 2016, 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 in 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 overdistributions for financial
    statement purposes resulting from differences in the recognition or
    classification of income or distributions for financial statement and tax
    purposes. Capital accounts within the financial statements are adjusted for
    permanent book/tax differences to reflect tax character, but are not
    adjusted for temporary differences.

    The tax character of 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, 2016 was as follows:



    ----------------------------------------------------------------------------
                                                                            2016
    ----------------------------------------------------------------------------
                                                                
    Distributions paid from:
    Ordinary income                                                $  16,761,660
    ----------------------------------------------------------------------------
         Total                                                     $  16,761,660
    ============================================================================


    The following shows components of distributable earnings on a federal income
    tax basis at December 31, 2016:



    ----------------------------------------------------------------------------
                                                                           2016
    ----------------------------------------------------------------------------
                                                                
    Distributable earnings:
    Undistributed ordinary income                                  $    321,901
    Capital loss carryforward                                       (38,019,147)
    Net unrealized appreciation                                     179,717,014
    ----------------------------------------------------------------------------
         Total                                                     $142,019,768
    ============================================================================


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

32 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


E.  Fund Shares

    The Fund records sales and repurchases of its shares as of trade date.
    Amundi Pioneer Distributor, Inc., formerly Pioneer Funds Distributor, Inc.
    (PFD), the principal underwriter for the Fund and a wholly owned indirect
    subsidiary of UniCredit, earned $28,669 in underwriting commissions on the
    sale of Class A shares during the six months ended June 30, 2017.

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

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

G.  Risks

    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 the Fund more
    susceptible to any economic, political, or regulatory developments or other
    risks affecting those industries and sectors. 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.  Futures Contracts

    The Fund may enter into futures transactions in order to attempt to hedge
    against changes in interest rates, securities prices and currency exchange
    rates or to seek to increase total return. Futures contracts are types of
    derivatives.  All futures contracts entered into by the Fund are traded on
    a futures exchange. Upon entering into a futures contract, the Fund is
    required to deposit with a broker an amount of cash or securities equal to
    the minimum

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 33


    "initial margin" requirements of the associated futures exchange.
    Subsequent payments for futures contracts ("variation margin") are paid or
    received by the Fund, depending on the daily fluctuation in the value of
    the contracts, and are recorded by the Fund as unrealized appreciation or
    depreciation.  When the contract is closed, the Fund realizes a gain or
    loss equal to the difference between the opening and closing value of the
    contract as well as any fluctuation in foreign currency exchange rates
    where applicable. Futures contracts are subject to market risk, interest
    rate risk and currency exchange rate risk. Changes in value of the
    contracts may not directly correlate to the changes in value of the
    underlying securities. The average value of contracts open during the six
    months ended June 30, 2017 was $7,443,544. There were no open futures
    contracts at June 30, 2017.

2.  Management Agreement

Amundi Pioneer, formerly PIM manages the Fund's portfolio. Management fees are
calculated daily at the annual rate of 0.50% of the Fund's average daily net
assets. For the six months ended June 30, 2017, the net management fee
(excluding waivers and/or assumption of expenses) was equivalent to 0.50% of the
Fund's average daily net assets.

In addition, under the management and administration agreements, certain other
services and costs, including accounting, regulatory reporting and insurance
premiums, are paid by the Fund as administrative reimbursements.  Included in
"Due to affiliates" reflected on the Statement of Assets and Liabilities is
$226,863 in management fees, administrative costs and certain other
reimbursements payable to Amundi Pioneer, formerly PIM at June 30, 2017.

3.  Transfer Agent

Boston Financial Data Services, 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 shareholder communications activities
such as proxy and statement mailings and outgoing phone calls. For the six
months ended June 30, 2017, such out-of-pocket expenses by class of shares were
as follows:



--------------------------------------------------------------------------------
Shareholder Communications:
--------------------------------------------------------------------------------
                                                                    
Class A                                                                $ 114,675
Class C                                                                    2,419
Class Y                                                                      260
--------------------------------------------------------------------------------
  Total                                                                $ 117,354
================================================================================


34 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


4.  Distribution Plan

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 and Class C
shares. Pursuant to the Plan, the Fund pays Amundi Pioneer Distributor, Inc.,
formerly PFD 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 Amundi Pioneer Distributor, Inc., formerly PFD 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 $108,159 in
distribution fees payable to Amundi Pioneer Distributor, Inc., formerly PFD at
June 30, 2017.

In addition, redemptions of each class of shares (except Class Y shares) may be
subject to a contingent deferred sales charge (CDSC). A CDSC of 1.00% may be
imposed on redemptions of certain net asset value purchases of Class A shares
within 12 months of purchase. Redemptions of Class C shares within 12 months of
purchase are subject to a CDSC of 1.00%, based on the lower of cost or market
value of shares being redeemed. Shares purchased as part of an exchange remain
subject to any CDSC that applied to the original purchase of those shares. There
is no CDSC for Class Y shares. Proceeds from the CDSC are paid to Amundi Pioneer
Distributor, Inc., formerly PFD. For the six months ended June 30, 2017, CDSC in
the amount of $664 were paid to Amundi Pioneer Distributor, Inc., formerly PFD.

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. The
credit facility in which the Fund participated until February 9, 2016 was in the
amount of $240 million. The credit facility in which the Fund participated until
February 7, 2017, was in the amount of $220 million. Effective February 8, 2017,
the Fund participated in a facility that is in the amount of $195 million. Under
such facility, depending on the type of loan, interest on borrowings is payable
at the London Interbank Offered Rate (LIBOR) plus 0.85% 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 and (c) 2% plus the overnight
Eurodollar rate on the borrowing date. The Funds

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 35


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, 2017, the Fund
had no borrowings under the credit facility.

6.  Additional Disclosures about Derivative Instruments and Hedging Activities

The Fund's use of derivatives subjects it to the following risks:

Interest rate risk relates to the fluctuations in the value of interest-bearing
securities due to changes in the prevailing levels of market interest rates.

Credit risk relates to the ability of the issuer of a financial instrument to
make further principal or interest payments on an obligation or commitment that
it has to the Fund.

Foreign exchange rate risk relates to fluctuations in the value of an asset or
liability due to changes in currency exchange rates.

Equity risk relates to the fluctuations in the value of financial instruments as
a result of changes in market prices (other than those arising from interest
rate risk or foreign exchange risk), whether caused by factors specific to an
individual investment, its issuer, or all factors affecting all instruments
traded in a market or market segment.

Commodity risk relates to the risk that the value of a commodity or commodity
index will fluctuate based on increases or decreases in the commodities market
and factors specific to a particular industry or commodity.

The effect of derivative instruments (not considered to be hedging instruments
for accounting disclosure purposes) on the Statement of Operations by risk
exposure at June 30, 2017 was as follows:



---------------------------------------------------------------------------------
Statement of Operations
                                              Foreign
                        Interest    Credit    Exchange     Equity       Commodity
                        Rate Risk   Risk      Rate Risk    Risk         Risk
---------------------------------------------------------------------------------
                                                         
Net realized gain
 (loss) on
 Futures contracts      $ --        $ --      $ --         $ (99,315)   $ --
---------------------------------------------------------------------------------
 Total Value            $ --        $ --      $ --         $ (99,315)   $ --
=================================================================================


36 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


7.  Results of Shareholder Meeting

At a special meeting held on June 13, 2017, shareholders of the Fund were asked
to consider the proposals described below. A report of the total votes cast by
the Fund's shareholders follows:



--------------------------------------------------------------------------------------------------
                             For               Against          Abstain          Broker Non-Votes
--------------------------------------------------------------------------------------------------
                                                                     
Proposal 1 - To approve      38,548,938.917    1,533,432.598    2,574,093.433    4,260,114.000
a New Management
Agreement with
the Adviser




-------------------------------------------------------------------------------------------
                                                        For                   Withhold
-------------------------------------------------------------------------------------------
                                                                        
Proposal 2 - To elect Trustees
-------------------------------------------------------------------------------------------
David R. Bock                                           44,984,657.790        1,931,921.158
-------------------------------------------------------------------------------------------
Benjamin M. Friedman                                    44,825,729.502        2,090,849.446
-------------------------------------------------------------------------------------------
Margaret B.W. Graham                                    44,923,396.418        1,993,182.530
-------------------------------------------------------------------------------------------
Lisa M. Jones                                           45,019,721.835        1,896,857.113
-------------------------------------------------------------------------------------------
Lorraine H. Monchak                                     44,863,646.305        2,052,932.643
-------------------------------------------------------------------------------------------
Thomas J. Perna                                         44,946,949.575        1,969,629.373
-------------------------------------------------------------------------------------------
Marguerite A. Piret                                     44,682,444.149        2,234,134.799
-------------------------------------------------------------------------------------------
Fred J. Ricciardi                                       44,784,799.755        2,131,779.193
-------------------------------------------------------------------------------------------
Kenneth J. Taubes                                       44,961,541.535        1,955,037.413
-------------------------------------------------------------------------------------------




------------------------------------------------------------------------------------------------
                              For              Against          Abstain         Broker Non-Votes
------------------------------------------------------------------------------------------------
                                                                    
Proposal 3 - To convert       33,230,899.784   4,381,650.955    5,043,910.209   4,260,118.000
investment objective(s)
from fundamental
to non-fundamental


                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 37


Additional Information

Change in Independent Registered Public Accounting Firm Prior to July 3, 2017
Pioneer Investment Management, Inc. (the "Adviser"), the Fund's investment
adviser, was an indirect, wholly owned subsidiary of UniCredit S.p.A.
("UniCredit"). On that date, UniCredit completed the sale of its Pioneer
Investments business, which includes the Adviser, to Amundi (the "Transaction").
As a result of the Transaction, the Adviser became an indirect, wholly-owned
subsidiary of Amundi. Amundi is controlled by Credit Agricole S.A. Amundi is
headquartered in Paris, France, and, as of September 30, 2016, had more than
$1.1 trillion in assets under management worldwide.

Deloitte & Touche LLP ("D&T"), the Fund's previous independent registered public
accounting firm, informed the Audit Committee and the Board that it would no
longer be independent with respect to the Fund upon the completion of the
Transaction as a result of certain services being provided to Amundi and Credit
Agricole, and, accordingly, that it intended to resign as the Fund's independent
registered public accounting firm upon the completion of the Transaction. D&T's
resignation was effective on July 3, 2017, when the Transaction was completed.

During the periods as to which D&T has served as the Fund's independent
registered public accounting firm, including the Fund's two most recent fiscal
years preceding the fiscal year ended December 31, 2017, D&T's reports on the
Fund's financial statements have not contained an adverse opinion or disclaimer
of opinion and have not been qualified or modified as to uncertainty, audit
scope or accounting principles. Further, there have been no disagreements with
D&T on any matter of accounting principles or practices, financial statement
disclosure, or auditing scope or procedure, which, if not resolved to the
satisfaction of D&T, would have caused D&T to make reference to the subject
matter of the disagreement in connection with its report on the financial
statements. In addition, there have been no reportable events of the kind
described in Item 304(a)(1)(v) of Regulation S-K under the Securities Exchange
Act of 1934.

Effective immediately following the completion of the Transaction on July 3,
2017, the Board, acting upon the recommendation of the Audit Committee, engaged
a new independent registered public accounting firm, Ernst & Young LLP ("EY"),
for the Fund's fiscal year ended December 31, 2017.

Prior to its engagement, EY had advised the Fund's Audit Committee that EY had
identified the following matters, in each case relating to services rendered by
other member firms of Ernst & Young Global Limited, all of which are located
outside the United States, to UniCredit and certain of its subsidiaries during
the period commencing July 1, 2016, that it determined to be inconsistent with
the auditor independence rules set forth by the Securities

38 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


and Exchange Commission ("SEC"): (a) project management support services to
UniCredit in the Czech Republic, Germany, Italy, Serbia and Slovenia in relation
to twenty-two projects, that were determined to be inconsistent with Rule
2-01(c)(4)(vi) of Regulation S-X (management functions); (b) two engagements for
UniCredit in Italy where fees were contingent/success based and that were
determined to be inconsistent with Rule 2-01(c)(5) of Regulation S-X (contingent
fees); (c) four engagements where legal and expert services were provided to
UniCredit in the Czech Republic and Germany, and twenty engagements where the
legal advisory services were provided to UniCredit in Austria, Czech Republic,
Italy and Poland, that were determined to be inconsistent with Rule
2-01(c)(4)(ix) and (x) of Regulation S-X (legal and expert services); and (d)
two engagements for UniCredit in Italy involving assistance in the sale of
certain assets, that were determined to be inconsistent with Rule
2-01(c)(4)(viii) of Regulation S-X (broker-dealer, investment advisor or
investment banking services). None of the foregoing services involved the Fund,
any of the other Funds in the Pioneer Family of Funds or any other Pioneer
entity sold by UniCredit in the Transaction.

EY advised the Audit Committee that it had considered the matters described
above and had concluded that such matters would not impair EY's ability to
exercise objective and impartial judgment in connection with the audits of the
financial statements of the Fund under the SEC and Public Company Accounting
Oversight Board independence rules, and that a reasonable investor with
knowledge of all relevant facts and circumstances would reach the same
conclusion. Management and the Audit Committee considered these matters and
discussed the matters with EY and, based upon EY's description of the matters
and statements made by EY, Management and the Audit Committee believe that EY
will be capable of exercising objective and impartial judgment in connection
with the audits of the financial statements of the Fund, and Management further
believes that a reasonable investor with knowledge of all relevant facts and
circumstances would reach the same conclusion.

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 39


Approval of New and Interim Management Agreements

Amundi Pioneer Asset Management, Inc. (Amundi Pioneer), formerly Pioneer
Investment Management, Inc. (PIM), serves as the investment adviser to Pioneer
Core Equity Fund (the Fund) pursuant to an investment management agreement
between Amundi Pioneer and the Fund.

On July 3, 2017, Amundi acquired Pioneer Investments, a group of asset
management companies located throughout the world (the "Transaction"). As a
result of the Transaction, Amundi Pioneer became an indirect wholly-owned
subsidiary of Amundi and Amundi's wholly-owned subsidiary, Amundi USA, Inc.
Prior to July 3, 2017, Pioneer Investments was owned by Pioneer Global Asset
Management S.p.A. ("PGAM"), a wholly-owned subsidiary of UniCredit S.p.A.
("UniCredit").

Under the Investment Company Act of 1940, the Fund's investment management
agreement with PIM (the "Current Management Agreement") terminated automatically
upon the consummation of the Transaction. In order for Amundi Pioneer to
continue to manage the Fund after the consummation of the Transaction, the
Trustees and shareholders of the Fund were required to approve a new investment
management agreement for the Fund (the "New Management Agreement"). As discussed
below, the Board of Trustees of the Fund approved the New Management Agreement
at a meeting held on March 6-7, 2017. The New Management Agreement was approved
by the shareholders of the Fund at a meeting held on June 13, 2017. The Board of
Trustees of the Fund also approved an interim investment management agreement
between Amundi Pioneer and the Fund (the "Interim Management Agreement") at the
March 6-7, 2017 meeting.  The Interim Management Agreement would have taken
effect upon the closing of the Transaction in the event that the shareholders of
the Fund did not approve the New Management Agreement.

Board Evaluation of the New and Interim Management Agreements

The Board evaluated the Transaction and the New Management Agreement and Interim
Management Agreement for the Fund. In connection with their evaluation of the
Transaction and the New Management Agreement for the Fund, the Trustees
requested such information as they deemed reasonably necessary, including: (a)
the structure of the Transaction and the strategy underlying the Transaction;
(b) the anticipated benefits of the Transaction to the Fund and its
shareholders; (c) the post-Transaction plans for Amundi Pioneer, including
Amundi's plans for integration of Pioneer Investments and Amundi Pioneer with
its existing asset management businesses and plans for the future development of
Amundi Pioneer; (d) the effect of the Transaction on the ongoing services
provided to the Fund, including the need to select a new independent registered
public accounting firm for the Fund, and any plans to modify the operations of
the Fund; (e) the stability and continuity of Amundi Pioneer's management and

40 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


key employees, including compensation and benefits to Amundi Pioneer's key
employees, and retention plans and incentive plan structure; (f) the post-
Transaction indebtedness and financial resources of Amundi Pioneer; (g) Amundi's
legal and operational structure, its principal shareholders and senior
management, its investment management, risk management, administrative, legal
and compliance functions; (h) certain regulatory matters relating to Amundi's
affiliates; and (i) Amundi's commitment to the United States, including the role
of Amundi Pioneer in the larger Amundi business.

The Trustees also requested and obtained the following information in connection
with their evaluation of the Transaction and the New Management Agreement for
the Fund: (i) memoranda provided by Fund counsel that summarized the legal
standards and other considerations that are relevant to the Trustees in their
deliberations regarding the New Management Agreement; (ii) the qualifications of
the investment management teams for the Fund, as well as the level of investment
by the Fund's portfolio managers in the Fund; (iii) the Fund's management fees
and total expense ratios, the financial statements of Amundi Pioneer and its
pre- and post-Transaction parent companies, profitability analyses from Amundi
Pioneer, and analyses from Amundi Pioneer as to possible economies of scale;
(iv) the profitability of the institutional business of Amundi Pioneer and
Amundi Pioneer's affiliate, Amundi Pioneer Institutional Asset Management, Inc.
("Amundi Pioneer Institutional") as compared to that of Amundi Pioneer's fund
management business; and (v) the differences between the fees and expenses of
the Fund and the fees and expenses of Amundi Pioneer's and Amundi Pioneer
Institutional's institutional accounts, as well as the different services
provided by Adviser to the Fund and by Amundi Pioneer and Amundi Pioneer
Institutional to the institutional accounts. In addition, the Trustees
considered the information provided at regularly scheduled meetings throughout
the year regarding the Fund's performance and risk attributes, including through
meetings with investment management personnel, and took into account other
information related to the Fund provided to the Trustees at regularly scheduled
meetings. The Trustees also considered information they had received in their
review of the continuance of the Current Management Agreement for the Fund in
September 2016.

At meetings held on January 9, 2017 and January 10, 2017, the Trustees met with
representatives of Amundi and PGAM, including separate meetings of the Trustees
who are not "interested persons" of the Fund Complex ("Independent Trustees")
and counsel with representatives of Amundi and PGAM, and subsequently with
representatives of Amundi. In those meetings, they received an extensive
presentation from the representatives of Amundi, including the chief executive
officer of Amundi, describing Amundi's background and history, its global asset
management activities, the growth of its business, and its status as the largest
asset management firm in Europe and one of the largest globally; its capital
structure and financial resources, including information as to the financing of
the

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 41


Transaction; its principal investors, including its majority investor Credit
Agricole S.A., and Credit Agricole's long-term commitment to the asset
management business; the philosophy and strategy underlying the Transaction and
the complementarity of Amundi's and Pioneer Investments' respective asset
management businesses; Amundi's various operating and investment committees and
how they would likely interact with Amundi Pioneer; the proposed integration
process, including the progress to date and the establishment of various
integration work streams; Amundi's plans for management of Amundi Pioneer;
Amundi's philosophy as to compensation of key employees and its general
intentions with respect to incentive plans for key employees of Amundi Pioneer;
Amundi's preliminary plans to achieve cost and other synergies; and
opportunities to further develop the business of Amundi Pioneer and Amundi
Pioneer Institutional, including in the area of institutional asset management,
and how that would benefit shareholders of the Pioneer Funds.

In those meetings, the representatives of Amundi confirmed their intention that
the Chief Executive Officer and Chief Investment Officer of Amundi Pioneer would
remain in their current positions, and confirmed that they do not currently
foresee major changes in the day-to-day investment management operations of
Amundi Pioneer with respect to the Fund as a direct result of the Transaction.
They discussed incentive arrangements for key personnel that would continue
after the closing of the Transaction and their plans to establish a new
long-term incentive plan following the closing. They also generally discussed
ways in which Amundi Pioneer could potentially draw on the expanded global
resources of Amundi post-Transaction. At those meetings, the Independent
Trustees identified certain areas to which they requested further information,
including as to trading and execution of securities transactions, research and
portfolio management and potential changes in investment process, particularly
where asset classes managed by Amundi Pioneer would overlap with asset classes
managed by Amundi, the continued availability of resources currently at Pioneer
Investments or elsewhere within Amundi to assist in management of certain Funds,
and any anticipated significant changes in operations. The Independent Trustees
considered the uncertainty as to whether the Fund's independent registered
public accounting firm could continue to act in that capacity after the closing
of the Transaction. The Independent Trustees also met with counsel to review the
information they had received to date and to discuss next steps.

Subsequently, the Trustees received further information from Amundi, including
written responses to questions raised by the Independent Trustees, and received
from Amundi Pioneer the information requested of it. The Independent Trustees
reviewed the information provided with counsel at telephonic meetings held on
February 16, 2017 and February 27, 2017. The Trustees held a special in-person
Board meeting on March 6-7, 2017 for further consideration of the New Management
Agreements, the Interim Management Agreements and the Transaction. The Trustees
met again with senior executives of Amundi at the March 6-7, 2017 meeting.

42 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


At the March 6-7, 2017 meeting, based on their evaluation of the information
provided by Amundi Pioneer and Amundi, the Trustees including the Independent
Trustees voting separately, approved the New Management Agreement and the
Interim Management Agreement for the Fund. In considering the New Management
Agreement for the Fund, the Trustees considered various factors that they
determined were relevant, including the factors described below.  The Trustees
did not identify any single factor as the controlling factor in their
determinations. The Trustees considered the same factors with respect to the
Interim Management Agreement for the Fund.

Nature, Extent and Quality of Services

The Trustees considered the nature, extent and quality of the services that had
been provided by Amundi Pioneer to the Fund and that are expected to be provided
by Amundi Pioneer to the Fund following the consummation of the Transaction. The
Trustees reviewed the terms of the New Management Agreement, and noted that such
terms are substantially similar to the terms of the Current Management
Agreement, except for different execution dates, effective dates and termination
dates. The Trustees reviewed Amundi Pioneer's investment approach for the Fund
and its research process. The Trustees considered the resources of Amundi
Pioneer and the personnel of Amundi Pioneer who provide investment management
services to the Fund. They also reviewed the amount of non-investment resources
and personnel of Amundi Pioneer that are involved in Amundi Pioneer's services
to the Fund, including Amundi Pioneer's compliance and legal resources and
personnel. The Trustees noted the substantial attention and high priority given
by Amundi Pioneer's senior management to the Pioneer Fund complex.

The Trustees considered that Amundi Pioneer supervises and monitors the
performance of the Fund's service providers and provides the Fund with personnel
(including Fund officers) and other resources that are necessary for the Fund's
business management and operations and that Amundi Pioneer would continue to
provide those investment management and research services and resources to the
Fund following the consummation of the Transaction. The Trustees also considered
that, as administrator, Amundi Pioneer would continue to be responsible for the
administration of the Fund's business and other affairs.  The Trustees
considered the fees to be paid to Amundi Pioneer for the provision of
administration services.

The Trustees considered that Deloitte & Touche LLP informed the Board that it
would no longer be independent with respect to the Fund upon the completion of
the Transaction and, accordingly, that it would be necessary for the Board to
engage a new independent registered public accounting firm for the Fund.

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 43


The Trustees considered that the Transaction was not expected to have a material
adverse impact on the nature, scope and overall quality of services provided to
the Fund and its shareholders, including investment management, risk management,
administrative, compliance, legal and other services, as a result of the
Transaction.

In that regard, the Trustees considered that Amundi is one of the largest asset
managers globally, and that Amundi Pioneer may have access to additional
research and portfolio management capabilities as a result of the Transaction
and that Amundi Pioneer, as part of Amundi, is expected to have an enhanced
global presence that may contribute to an increase in the overall scale and
resources of Amundi Pioneer. Furthermore, in considering whether the Transaction
would be expected to have a material adverse impact on the nature, scope and
overall quality of services provided to the Fund and its shareholders, the
Trustees considered the statements by representatives of Amundi that they expect
the Chief Executive Officer and Chief Investment Officer of Amundi Pioneer to
remain in their current positions and that they do not currently foresee major
changes in the day-to-day investment management operations of Amundi Pioneer as
a direct result of the Transaction, or the risk management, legal or compliance
services provided by Amundi Pioneer, with respect to the Fund. They further
considered the current incentive arrangements for key personnel of Amundi
Pioneer that would continue after the closing of the Transaction. They also
noted Amundi's stated intention to establish a new long-term incentive plan
following the closing.

The Trustees also took into account their experience in evaluating the proposed
combination of Pioneer Investments and Santander Asset Management, which was
announced in September, 2014 and abandoned in July, 2016. In light of, among
other things, this experience, the Trustees determined that they were not able
to identify any realistic alternatives to approving the New Management Agreement
that would provide the level of services to the Fund and its shareholders that
are expected to be provided by Amundi Pioneer after the closing of the
Transaction.

Based on these considerations, the Trustees concluded that the nature, extent
and quality of services that Amundi Pioneer would continue to provide to the
Fund under the New Management Agreement would be satisfactory and consistent
with the terms of the New Management Agreement.

Performance of the Fund

In considering the Fund's performance, the Trustees regularly reviewed and
discussed throughout the year data prepared by Amundi Pioneer and information
comparing the Fund's performance with the performance of its peer group of
funds, as classified by each of Morningstar, Inc. (Morningstar) and Lipper, and
the performance of the Fund's benchmark index. They also discussed the Fund's
performance with Amundi Pioneer on a regular basis.

44 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


The Trustees discussed the Fund's performance with Amundi Pioneer on a more
frequent basis in light of the Fund's unfavorable performance compared to its
benchmark index and peers over certain periods. The Trustees noted Amundi
Pioneer's explanation for the Fund's relative performance and the steps taken by
Amundi Pioneer to address the Fund's performance, including enhancing the
investment process used for the Fund. It also was noted that Craig Sterling, a
Senior Vice President and Head of Equity Research, U.S., became a portfolio
manager of the Fund in May, 2015.

The Trustees' regular reviews and discussions, including the steps taken by
Amundi Pioneer to address the Fund's performance, were factored into the
Trustees' deliberations concerning the approval of the New Management Agreement.

Management Fee and Expenses

The Trustees noted that the stated management fees to be paid by the Fund are
identical under the Current Management Agreement and the New Management
Agreement. The Trustees considered information showing the fees and expenses of
the Fund in comparison to the management fees and expense ratios of its peer
group of funds as classified by Morningstar and also to the expense ratios of a
peer group of funds selected on the basis of criteria determined by the
Independent Trustees for this purpose using data provided by Strategic Insight
Mutual Fund Research and Consulting, LLC (Strategic Insight), an independent
third party. In all quintile rankings referred to below, first quintile is most
favorable to the Fund's shareowners. To the extent applicable, the Trustees also
considered the impact of transfer agency, sub-transfer agency, and other non-
management fee expenses on the expense ratios of the Fund. The Trustees noted
that they separately review the Fund's transfer agency, sub-transfer agency and
intermediary arrangements and that the results of the most recent such review
were considered in the consideration of the Fund's expense ratio.

The Trustees considered that the Fund's management fee as of September 30, 2016
was in the first quintile relative to the management fees paid by other funds in
its Morningstar category for the comparable period. The Trustees considered that
the expense ratio of the Fund's Class A shares as of September 30, 2016 was in
the first quintile relative to its Morningstar category and in the first
quintile relative to its Strategic Insight peer group, in each case for the
comparable period.

The Trustees reviewed management fees charged by Amundi Pioneer and Amundi
Pioneer Institutional to institutional and other clients, including publicly
offered European funds sponsored by Amundi Pioneer's affiliates, unaffiliated
U.S.  registered investment companies (in a sub-advisory capacity), and
unaffiliated foreign and domestic separate accounts. The Trustees also
considered Amundi Pioneer's costs in providing services to the Fund and Amundi
Pioneer's and Amundi Pioneer Institutional's costs in providing services to the
other clients and considered the differences in management fees and profit
margins for fund and

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 45


non-fund services. In evaluating the fees associated with Amundi Pioneer's and
Amundi Pioneer Institutional's client accounts, the Trustees took into account
the respective demands, resources and complexity associated with the Fund and
other client accounts. The Trustees noted that in some instances the fee rates
for those clients were lower than the management fee for the Fund and considered
that, under both the Current Management Agreement and the New Management
Agreement, Amundi Pioneer would perform additional services for the Fund that it
does not provide to those other clients or services that are broader in scope,
including oversight of the Fund's other service providers and activities related
to compliance and the extensive regulatory and tax regimes to which the Fund is
subject. The Trustees also considered the different risks associated with Amundi
Pioneer's management of the Fund and Amundi Pioneer's and Amundi Pioneer
Institutional's management of the other client accounts.

The Trustees concluded that the management fee payable by the Fund to Amundi
Pioneer was reasonable in relation to the nature and quality of the services to
be provided by Amundi Pioneer.

Profitability

The Trustees considered information provided by Amundi Pioneer regarding the
profitability of Amundi Pioneer with respect to the advisory services provided
by Amundi Pioneer to the Fund, including the methodology used by Amundi Pioneer
in allocating certain of its costs to the management of the Fund. The Trustees
also considered Amundi Pioneer's profit margin in connection with the overall
operation of the Fund. They further reviewed the financial results, including
the profit margins, realized by Amundi Pioneer and Amundi Pioneer Institutional
from non-fund businesses. The Trustees considered Amundi Pioneer's profit
margins with respect to the Fund in comparison to the limited industry data
available and noted that the profitability of any adviser was affected by
numerous factors, including its organizational structure and method for
allocating expenses. The Trustees concluded that Amundi Pioneer's profitability
with respect to the management of the Fund was not unreasonable.

Economies of Scale

The Trustees considered Amundi Pioneer's views relating to economies of scale in
connection with the Pioneer Funds as fund assets grow and the extent to which
any such economies of scale are shared with the Fund and Fund shareholders. The
Trustees recognize that economies of scale are difficult to identify and
quantify, and that, among other factors that may be relevant, are the following:
fee levels, expense subsidization, investment by Amundi Pioneer in research and
analytical capabilities and Amundi Pioneer's commitment and resource allocation
to the Fund. The Trustees noted that profitability also may be an indicator of
the availability of any economies of scale, although profitability may vary for
other reasons including due to reductions in expenses. The Trustees concluded
that economies of scale, if any, were being appropriately shared with the Fund.

46 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


Other Benefits

The Trustees considered the other benefits that Amundi Pioneer enjoys from its
relationship with the Fund. The Trustees considered the character and amount of
fees paid or to be paid by the Fund, other than under the Current Management
Agreement or the New Management Agreement, for services provided by Amundi
Pioneer and its affiliates. The Trustees further considered the revenues and
profitability of Amundi Pioneer's businesses other than the Fund business.  To
the extent applicable, the Trustees also considered the benefits to the Fund and
to Amundi Pioneer and its affiliates from the use of "soft" commission dollars
generated by the Fund to pay for research and brokerage services.

The Trustees considered that following the completion of the Transaction, Amundi
Pioneer will be the principal U.S. asset management business of Amundi, and that
Amundi's worldwide asset management business will manage over $1.38 trillion in
assets (including the Pioneer Funds). This may create opportunities for Amundi
Pioneer, Amundi Pioneer Institutional and Amundi that derive from Amundi
Pioneer's relationships with the Fund, including Amundi's ability to market the
services of Amundi Pioneer globally. The Trustees noted that Amundi Pioneer may
have access to additional research capabilities as a result of the Transaction
and Amundi's enhanced global presence that may contribute to an increase of the
overall scale of Amundi Pioneer. The Trustees considered that Amundi Pioneer and
the Fund are expected to receive reciprocal intangible benefits from the
relationship, including mutual brand recognition and, for the Fund, direct and
indirect access to the resources of a large global asset manager. The Trustees
concluded that any such benefits received by Amundi Pioneer as a result of its
relationship with the Fund were reasonable.

Conclusion

After consideration of the factors described above as well as other factors, the
Trustees, including the Independent Trustees, concluded that the New Management
Agreement and the Interim Management Agreement for the Fund, including the fees
payable thereunder, were fair and reasonable and voted to approve the New
Management Agreement and the Interim Management Agreement, and to recommend that
shareholders approve the New Management Agreement.

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 47


Trustees, Officers and Service Providers

Trustees                                    Officers
Thomas J. Perna, Chairman                   Lisa M. Jones, President and Chief
David R. Bock                                 Executive Officer
Benjamin M. Friedman                        Mark E. Bradley, Treasurer and
Margaret B.W. Graham                          Chief Financial 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., formerly
Pioneer Investment Management, Inc.

Custodian and Sub-Administrator
Brown Brothers Harriman & Co.

Principal Underwriter
Amundi Pioneer Distributor, Inc., formerly
Pioneer Funds Distributor, Inc.

Legal Counsel
Morgan, Lewis & Bockius LLP

Shareowner Services and Transfer Agent
Boston Financial Data Services, Inc.

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

48 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


                          This page is for your notes.

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 49

                          This page is for your notes.

50 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


                          This page is for your notes.

                       Pioneer Core Equity Fund | Semiannual Report | 6/30/17 51


                          This page is for your notes.

52 Pioneer Core Equity Fund | Semiannual Report | 6/30/17


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

FactFone(SM) for automated fund yields, prices,
account information and transactions                              1-800-225-4321

Retirement plans information                                      1-800-622-0176

Write to us:
--------------------------------------------------------------------------------
Amundi Pioneer
P.O. Box 55014
Boston, Massachusetts 02205-5014

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

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

Visit our web site: www.amundipioneer.com

This report must be preceded or accompanied by a prospectus.

The Fund files a complete schedule of investments with the Securities and
Exchange Commission for the first and third quarters for each fiscal year on
Form N-Q. Shareholders may view the filed Form N-Q by visiting the Commission's
web site at http://www.sec.gov. The filed form may also be viewed and copied at
the Commission's Public Reference Room in Washington, DC. Information regarding
the operations of the Public Reference Room may be obtained by calling
1-800-SEC-0330.


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

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

Securities offered through Amundi Pioneer Distributor, Inc.
60 State Street, Boston, MA 02109
Underwriter of Pioneer Mutual Funds, Member SIPC
(C) 2017 Amundi Pioneer Asset Management 19408-11-0817




ITEM 2. CODE OF ETHICS.

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

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

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

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

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

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

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

        (5) Accountability for adherence to the code.

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

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

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

Not applicable.

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

Not applicable.

(f) The registrant must:

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

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

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

ITEM 3. AUDIT COMMITTEE FINANCIAL EXPERT.

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

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

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

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

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

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

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

Ms. Marguerite A. Piret, an independent trustee, is such an audit committee
financial expert.

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

Not applicable.


ITEM 4. PRINCIPAL ACCOUNTANT FEES AND SERVICES.

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

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 Pioneer Investment Management, Inc ("PIM"), 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.

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. 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, 2017


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, 2017


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

Date August 29, 2017

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