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                                 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 811-01466

                          	Pioneer Fund
               (Exact name of registrant as specified in charter)


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


            Terrence J. Cullen, 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, 2013 through June 30, 2013


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 SHAREOWNERS.


                  Pioneer Fund

--------------------------------------------------------------------------------
                  Semiannual Report | June 30, 2013
--------------------------------------------------------------------------------

                  Ticker Symbols:

                  Class A    PIODX
                  Class B    PBODX
                  Class C    PCODX
                  Class R    PIORX
                  Class Y    PYODX
                  Class Z    PIOZX

                  [LOGO] PIONEER
                         Investments(R)
<PAGE>

                      visit us: us.pioneerinvestments.com
<PAGE>

Table of Contents

<TABLE>
<S>                                                                          <C>
Letter to Shareowners                                                         2

Portfolio Management Discussion                                               4

Portfolio Summary                                                             7

Prices and Distributions                                                      8

Performance Update                                                            9

Comparing Ongoing Fund Expenses                                              15

Schedule of Investments                                                      17

Financial Statements                                                         25

Notes to Financial Statements                                                35

Trustees, Officers and Service Providers                                     44
</TABLE>

                                    Pioneer Fund | Semiannual Report | 6/30/13 1
<PAGE>

President's Letter

Dear Shareowner,

When we look at the U.S. economy as we head into the second half of 2013, we
continue to see slow, but ongoing, growth. Employment has been steadily rising.
Consumer incomes, savings, wealth, and debt-servicing capacity have been solid
buttresses for the recovering housing and auto industries. Industrial activity
is growing only modestly, but current corporate profits are generally solid and
balance sheets appear able to support needed capital spending and dividend*
payouts. The scaled-back "fiscal cliff" tax increases and spending cuts have
meaningfully cut the budget deficit without, it seems, driving the economy back
into recession. In addition, we feel that continuing slack in labor markets and
capacity utilization offers the potential for continuing growth without
bottlenecks and rising inflation.

After observing the strengthening economic trends, the Federal Reserve (the Fed)
has hinted that it may begin to scale back its bond purchases (currently $85
billion per month in quantitative easing, or "QE") later in 2013, and could
terminate the purchases altogether sometime in 2014, depending on subsequent
economic data releases. Pioneer believes that, barring an external shock, modest
economic growth can be sustained at least over the next couple of years without
continuous, aggressive intervention from the Fed.

The Fed has also said that short-term interest rates are likely to remain near
zero for some time to come. Given that inflation remains subdued and
unemployment remains high, there is no urgency about raising rates.

While inflation is not a near-term concern, the Fed's aggressive monetary
policies helped investors drive long-term Treasury yields to unsustainably low
levels. A return to more normal levels in response to expectations of a stronger
economy and the potential for less QE resulted in disappointing returns for bond
investors during the first half of 2013, but the stock market rewarded
shareholders who were undaunted by the double-barreled threat of the "fiscal
cliff" and debt-ceiling debates at the beginning of 2013.

The Standard & Poor's 500 Index, a broad measure of the U.S. stock market,
returned 13.82% during the first six months of 2013, while the Barclays
Aggregate Bond Index, which tracks the performance of a higher-quality U.S. bond
universe, returned -2.44%. Investors showed a rising preference for
higher-yielding corporate paper over government bonds during the first half of
2013, helping the Bank of America Merrill Lynch High Yield Master II Index,
which measures the performance of high-yield corporate bonds, to post a 1.50%
return for the six months ended June 30, 2013. Three-month Treasury bills,
generally regarded as essentially "risk free" by the markets, returned 0.03% in
the first half of 2013.

*    Dividends are not guaranteed.

2 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

There are certainly risks and uncertainties that continue to plague the global
economy. Europe remains in recession and a number of countries in the emerging
markets have experienced difficulties. Still, a potential ending of the European
recession, continuing economic improvement in Japan in response to the new
government's quantitative easing policies, and a "soft landing" of 7% growth in
China could very well result in an improving global outlook over the remainder
of 2013.

There are also geopolitical worries abroad and political fights at home, and
while most of the widely recognized risks we've outlined may already be "priced
in" to the market, we believe investors should continue to expect market
volatility.

At Pioneer, we have long advocated the benefits of staying diversified and
investing for the long term. And while diversification alone does not assure a
profit or protect against loss in a declining market, we believe there are still
opportunities for prudent investors to earn attractive returns. Our advice, as
always, is to work closely with a trusted financial advisor to discuss your
goals and work together to develop an investment strategy that meets your
individual needs, keeping in mind that there is no single best strategy that
works for every investor.

Pioneer's investment teams have, since 1928, sought out attractive opportunities
in global equity and bond markets, using in-depth research to identify
undervalued individual securities, and using thoughtful risk management to
construct portfolios which balance potential risks and rewards in an
ever-changing world.

We encourage you to learn more about Pioneer and our time-tested approach to
investing by consulting with your financial advisor or visiting us online at
us.pioneerinvestments.com. We greatly appreciate your trust in us, and we thank
you for investing with Pioneer.

Sincerely,

/s/ Daniel K. Kingsbury

Daniel K. Kingsbury
President and CEO
Pioneer Investment Management USA, Inc.

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. These statements should not
be relied upon for any other purposes. Past performance is no guarantee of
future results, and there is no guarantee that market forecasts discussed will
be realized.

                                    Pioneer Fund | Semiannual Report | 6/30/13 3
<PAGE>

Portfolio Management Discussion | 6/30/13

In the following interview, John Carey, Executive Vice President and Head of
U.S. Core Value at Pioneer Investments, discusses the investment environment
during the six-month period ended June 30, 2013, and Pioneer Fund's performance
during the period. Mr. Carey is responsible for the day-to-day management of
Pioneer Fund.

Q    How would you describe the market for equities during the six months ended
     June 30, 2013?

A    The stock market trended steadily higher through the middle of May, but a
     mild correction ensued for the next month as investors fretted about
     indications from the Federal Reserve Board (the Fed) that it might "taper"
     its bond purchases at some point and let interest rates find their own
     level. The final week of the six-month period saw a sharp rebound as
     investors took heart from projections of continued low inflation and
     moderate economic growth.

     Dividend-paying* stocks, especially those in sectors such as consumer
     discretionary and health care, were popular with investors during the six-
     month period. Merger-and-acquisition activity also affected the Fund's
     portfolio when, in February, H. J. Heinz received a premium take-over bid
     from Berkshire Hathaway and a Brazilian company called 3G Capital.

Q    How did the Fund perform in that environment during the six months ended
     June 30, 2013?

A    Pioneer Fund's Class A shares returned 13.78% at net asset value during the
     six months ended June 30, 2013, while the Fund's benchmark, the Standard &
     Poor's 500 Index (the S&P 500), returned 13.82%. During the same period,
     the average return of the 973 mutual funds Lipper's Large Cap Core Funds
     category was 13.19%.

Q    What were some of the key drivers of the Fund's benchmark-relative returns
     during the six months ended June 30, 2013?

A    While the Fund showed positive performance attribution across most sectors
     compared with the S&P 500, stock selection results in consumer
     discretionary and financials detracted from relative returns. In consumer
     discretionary, the Fund's shares of publisher John Wiley & Sons lagged; and
     in financials, not owning above-average performer Berkshire Hathaway hurt
     the Fund's results.

*    Dividends are not guaranteed.

4 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

     The biggest positive contributions to benchmark-relative returns during the
     period came from the Fund's underweight position in poor-performer Apple.
     The Fund also benefited from having overweight positions in strong
     performers Vertex Pharmaceuticals, Hershey, Cabot Oil & Gas, PNC Financial,
     H.J. Heinz, Celgene, and Becton Dickinson.

     Overall sector allocation results also contributed to relative returns
     during the six-month period.

Q    Could you summarize purchases and sales that you made in the Fund during
     the six months ended June 30, 2013?

A    The Fund held nine new positions at period end, while thirteen were
     liquidated during the six-month period.

     New additions Cameron International and FMC Technologies expanded the
     Fund's holdings in energy equipment and services. Both firms are known
     especially for their specialties in technologically-advanced, offshore
     drilling and production. Monsanto, a world leader in agricultural chemicals
     and seeds, also was added to the Fund during the period, as were Keycorp
     and Goldman Sachs, which provide exposures to areas in financial services
     that have seen sharp improvement since the troubled years between 2007 and
     2009. In consumer staples, we added PepsiCo, a pre-eminent name globally
     both in soft drinks and beverages as well as in snack foods, where the
     company's Frito-Lay division is famous. Another Fund entry, Raytheon,
     provides diversification into air-defense missiles and radar.

     In addition to making those purchases, the Fund received shares of AbbVie
     when an existing holding, Abbott Laboratories, split off its pharmaceutical
     business. Zoetis, an animal-health medicines company, initially came into
     the Fund's portfolio through purchases, when Pfizer, also an existing
     holding, had an initial public offering for that profitable division of its
     business. We expanded the Fund's Zoetis position through additional
     purchases and acceptance of an exchange offer from Pfizer.

     Among stocks sold from the Fund's portfolio during the period were several
     that we felt had reached fair value, including Vertex Pharmaceuticals,
     Qualcomm, and Sandisk; some where we had come to question the companies'
     longer-term, earnings-growth potential, including Exxon Mobil, Agilent
     Technologies, and AT&T; and others we just regarded as having less
     compelling prospects than those of companies whose stocks we wished to
     purchase.

                                    Pioneer Fund | Semiannual Report | 6/30/13 5
<PAGE>

Q    Given the various potential headwinds for the global economy, what is your
     outlook for the remainder of 2013?

A    Certainly there are risks and uncertainties for the global economy. Europe
     remains sluggish; growth in China appears to have slowed over the past
     couple of years from its former, very robust rate; Brazil, Argentina, and
     Venezuela, among other Latin American countries, have been experiencing
     difficulties; and here in the U.S., the national fiscal situation continues
     to cause unease. Besides the economic issues, there are also some obvious
     geopolitical trouble spots in the world, including the Middle East and the
     Korean peninsula.

     However, when we look at the U.S., the principal economic arena for the
     majority of the Fund's holdings, we see steady, if moderate, growth that we
     think can be sustained at least over the next couple of years by
     improvement in the housing sector, higher auto sales, and falling
     unemployment. The domestic economy, unlike economies in some other parts of
     the world, is predominantly dependent on the state of the consumer and the
     level of consumer confidence. A better housing market can go a long ways
     all by itself towards creating a more upbeat set of economic conditions.
     Next to the potential for the U.S. economy to keep expanding we would set
     the historically reasonable level of share-price valuations and the decent
     dividend yields relative to income-generating alternatives like money-
     market instruments and investment-grade bonds.

     So, headwinds, yes, but also, perhaps, some tailwinds. We shall see in the
     months and quarters ahead where the prevailing winds blow.

     Thank you for your interest and support.

Please refer to the Schedule of Investments on pages 17-24 for a full listing of
Fund securities.

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.

Past performance is no guarantee of future results, and there is no guarantee
that market forecasts discussed will be realized.

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. These opinions should not
be relied upon for any other purposes.

6 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

Portfolio Summary | 6/30/13

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

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

<TABLE>
<CAPTION>
<S>                                                                       <C>
U.S. Common Stocks                                                        96.0%
International Common Stocks                                                3.4%
Depositary Receipts for International Stocks                               0.6%
</TABLE>

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

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

<TABLE>
<CAPTION>
<S>                                                                       <C>
Information Technology                                                    17.2%
Financials                                                                16.4%
Health Care                                                               15.4%
Consumer Discretionary                                                    13.7%
Consumer Staples                                                          11.7%
Industrials                                                               11.5%
Energy                                                                     9.5%
Materials                                                                  2.8%
Utilities                                                                  1.0%
Telecommunication Services                                                 0.8%
</TABLE>

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

<TABLE>
<CAPTION>
<S>                                                                        <C>
 1. The Hershey Co.                                                        2.60%
--------------------------------------------------------------------------------
 2. John Wiley & Sons, Inc.                                                2.33
--------------------------------------------------------------------------------
 3. Wells Fargo & Co.                                                      2.28
--------------------------------------------------------------------------------
 4. Microsoft Corp.                                                        2.14
--------------------------------------------------------------------------------
 5. Colgate-Palmolive Co.                                                  2.09
--------------------------------------------------------------------------------
 6. Johnson & Johnson Co.                                                  1.85
--------------------------------------------------------------------------------
 7. The PNC Financial Services Group, Inc.                                 1.83
--------------------------------------------------------------------------------
 8. Apple, Inc.                                                            1.73
--------------------------------------------------------------------------------
 9. The Chubb Corp.                                                        1.73
--------------------------------------------------------------------------------
10. United Technologies Corp.                                              1.63
--------------------------------------------------------------------------------
</TABLE>

*    This list excludes temporary cash investments and derivative instruments.
     The portfolio is actively managed, and current holdings may be different.
     The holdings listed should not be considered recommendations to buy or sell
     any security listed.

                                    Pioneer Fund | Semiannual Report | 6/30/13 7
<PAGE>

Prices and Distributions | 6/30/13

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

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------
         Class                         6/30/13                    12/31/12
--------------------------------------------------------------------------------
<S>                                    <C>                         <C>
          A                            $36.74                      $32.45
--------------------------------------------------------------------------------
          B                            $35.35                      $31.26
--------------------------------------------------------------------------------
          C                            $34.68                      $30.64
--------------------------------------------------------------------------------
          R                            $36.83                      $32.51
--------------------------------------------------------------------------------
          Y                            $36.94                      $32.61
--------------------------------------------------------------------------------
          Z                            $36.84                      $32.53
--------------------------------------------------------------------------------
</TABLE>

Distributions per Share: 1/1/13-6/30/13
--------------------------------------------------------------------------------

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------
                      Net Investment       Short-Term        Long-Term
        Class             Income          Capital Gains     Capital Gains
--------------------------------------------------------------------------------
<S>                      <C>                  <C>              <C>
          A              $0.1800              $  --            $  --
--------------------------------------------------------------------------------
          B              $    --              $  --            $  --
--------------------------------------------------------------------------------
          C              $0.0500              $  --            $  --
--------------------------------------------------------------------------------
          R              $0.1200              $  --            $  --
--------------------------------------------------------------------------------
          Y              $0.2300              $  --            $  --
--------------------------------------------------------------------------------
          Z              $0.1900              $  --            $  --
--------------------------------------------------------------------------------
</TABLE>

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 9-14.

8 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

Performance Update | 6/30/13                                      Class A Shares

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

<TABLE>
<CAPTION>
Average Annual Total Returns
(As of June 30, 2013)
--------------------------------------------------------------------------------
                  Net Asset            Public Offering
Period            Value (NAV)          Price (POP)
--------------------------------------------------------------------------------
<S>               <C>                  <C>
10 Years           6.55%                5.92%
5 Years            4.51                 3.28
1 Year            19.49                12.63
--------------------------------------------------------------------------------

<CAPTION>
Expense Ratio
(Per prospectus dated May 1, 2013)
--------------------------------------------------------------------------------
                  Gross
--------------------------------------------------------------------------------
<S>               <C>
                  1.01%
--------------------------------------------------------------------------------
</TABLE>

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

Value of $10,000 Investment

<TABLE>
<CAPTION>
                  Pioneer Fund         Standard & Poor's 500 Index
<S>               <C>                  <C>
6/30/2003         $  9,425             $ 10,000
6/30/2004         $ 11,135             $ 11,910
6/30/2005         $ 12,069             $ 12,662
6/30/2006         $ 13,565             $ 13,754
6/30/2007         $ 16,295             $ 16,584
6/30/2008         $ 14,258             $ 14,410
6/30/2009         $ 10,525             $ 10,635
6/30/2010         $ 11,826             $ 12,169
6/30/2011         $ 15,574             $ 15,903
6/30/2012         $ 14,879             $ 16,766
6/30/2013         $ 17,779             $ 20,217
</TABLE>

Call 1-800-225-6292 or visit us.pioneerinvestments.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.

                                    Pioneer Fund | Semiannual Report | 6/30/13 9
<PAGE>

Performance Update | 6/30/13                                      Class B Shares

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

<TABLE>
<CAPTION>
Average Annual Total Returns
(As of June 30, 2013)
--------------------------------------------------------------------------------
                  If                   If
Period            Held                 Redeemed
--------------------------------------------------------------------------------
<S>               <C>                  <C>
10 Years           5.47%                5.47%
5 Years            3.34                 3.34
1 Year            18.02                14.40
--------------------------------------------------------------------------------

<CAPTION>
Expense Ratio
(Per prospectus dated May 1, 2013)
--------------------------------------------------------------------------------
                  Gross
--------------------------------------------------------------------------------
<S>               <C>
                  2.27%
--------------------------------------------------------------------------------
</TABLE>

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

Value of $10,000 Investment

<TABLE>
<CAPTION>
                  Pioneer Fund         Standard & Poor's 500 Index
<S>               <C>                  <C>
6/30/2003         $ 10,000             $ 10,000
6/30/2004         $ 11,704             $ 11,910
6/30/2005         $ 12,575             $ 12,662
6/30/2006         $ 13,999             $ 13,754
6/30/2007         $ 16,679             $ 16,584
6/30/2008         $ 14,462             $ 14,410
6/30/2009         $ 10,566             $ 10,635
6/30/2010         $ 11,744             $ 12,169
6/30/2011         $ 15,295             $ 15,903
6/30/2012         $ 14,439             $ 16,766
6/30/2013         $ 17,040             $ 20,217
</TABLE>

Call 1-800-225-6292 or visit us.pioneerinvestments.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.

"If Held" results represent the percent change in net asset value per share.
Returns would have been lower had sales charges been reflected. "If Redeemed"
returns reflect the deduction of applicable contingent deferred sales charge
(CDSC). The maximum CDSC for Class B shares is 4% and declines over five years.
For more complete information, please see the prospectus.

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 taxes that a
shareowner would pay on Fund distributions or the redemption of Fund shares.

10 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

Performance Update | 6/30/13                                      Class C Shares

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

<TABLE>
<CAPTION>
Average Annual Total Returns
(As of June 30, 2013)
--------------------------------------------------------------------------------
                  If                   If
Period            Held                 Redeemed
--------------------------------------------------------------------------------
<S>               <C>                  <C>
10 Years           5.72%                5.72%
5 Years            3.70                 3.70
1 Year            18.56                18.56
--------------------------------------------------------------------------------

<CAPTION>
Expense Ratio
(Per prospectus dated May 1, 2013)
--------------------------------------------------------------------------------
                  Gross
--------------------------------------------------------------------------------
<S>               <C>
                  1.80%
--------------------------------------------------------------------------------
</TABLE>

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

Value of $10,000 Investment

<TABLE>
<CAPTION>
                  Pioneer Fund         Standard & Poor's 500 Index
<S>               <C>                  <C>
6/30/2003         $ 10,000             $ 10,000
6/30/2004         $ 11,718             $ 11,910
6/30/2005         $ 12,599             $ 12,662
6/30/2006         $ 14,054             $ 13,754
6/30/2007         $ 16,747             $ 16,584
6/30/2008         $ 14,540             $ 14,410
6/30/2009         $ 10,651             $ 10,635
6/30/2010         $ 11,872             $ 12,169
6/30/2011         $ 15,515             $ 15,903
6/30/2012         $ 14,708             $ 16,766
6/30/2013         $ 17,439             $ 20,217
</TABLE>

Call 1-800-225-6292 or visit us.pioneerinvestments.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). The performance of Class C shares does not reflect
the 1% front-end sales charge in effect prior to February 1, 2004. 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.

                                   Pioneer Fund | Semiannual Report | 6/30/13 11
<PAGE>

Performance Update | 6/30/13                                      Class R Shares

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

<TABLE>
<CAPTION>
Average Annual Total Returns
(As of June 30, 2013)
--------------------------------------------------------------------------------
                  If                   If
Period            Held                 Redeemed
--------------------------------------------------------------------------------
<S>               <C>                  <C>
10 Years           6.36%                6.36%
5 Years            4.24                 4.24
1 Year            19.18                19.18
--------------------------------------------------------------------------------

<CAPTION>
Expense Ratio
(Per prospectus dated May 1, 2013)
--------------------------------------------------------------------------------
                  Gross
--------------------------------------------------------------------------------
<S>               <C>
                  1.33%
--------------------------------------------------------------------------------
</TABLE>

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

Value of $10,000 Investment

<TABLE>
<CAPTION>
                  Pioneer Fund         Standard & Poor's 500 Index
<S>               <C>                  <C>
6/30/2003         $ 10,000             $ 10,000
6/30/2004         $ 11,813             $ 11,910
6/30/2005         $ 12,793             $ 12,662
6/30/2006         $ 14,360             $ 13,754
6/30/2007         $ 17,223             $ 16,584
6/30/2008         $ 15,050             $ 14,410
6/30/2009         $ 11,097             $ 10,635
6/30/2010         $ 12,427             $ 12,169
6/30/2011         $ 16,307             $ 15,903
6/30/2012         $ 15,540             $ 16,766
6/30/2013         $ 18,520             $ 20,217
</TABLE>

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

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

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

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

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

12 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

Performance Update | 6/30/13                                      Class Y Shares

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

<TABLE>
<CAPTION>
Average Annual Total Returns
(As of June 30, 2013)
--------------------------------------------------------------------------------
                  If                   If
Period            Held                 Redeemed
--------------------------------------------------------------------------------
<S>               <C>                  <C>
10 Years           7.00%                7.00%
5 Years            4.95                 4.95
1 Year            19.91                19.91
--------------------------------------------------------------------------------

<CAPTION>
Expense Ratio
(Per prospectus dated May 1, 2013)
--------------------------------------------------------------------------------
                  Gross
--------------------------------------------------------------------------------
<S>               <C>
                  0.66%
--------------------------------------------------------------------------------
</TABLE>

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

Value of $5 Million Investment

<TABLE>
<CAPTION>
                  Pioneer Fund         Standard & Poor's 500 Index
<S>               <C>                  <C>
6/30/2003         $ 5,000,000          $  5,000,000
6/30/2004         $ 5,933,416          $  5,954,934
6/30/2005         $ 6,458,066          $  6,331,187
6/30/2006         $ 7,290,120          $  6,877,205
6/30/2007         $ 8,791,047          $  8,292,105
6/30/2008         $ 7,723,074          $  7,204,756
6/30/2009         $ 5,731,085          $  5,317,322
6/30/2010         $ 6,468,369          $  6,084,567
6/30/2011         $ 8,550,863          $  7,951,293
6/30/2012         $ 8,201,088          $  8,382,893
6/30/2013         $ 9,834,269          $ 10,108,414
</TABLE>

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

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

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

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

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

                                   Pioneer Fund | Semiannual Report | 6/30/13 13
<PAGE>

Performance Update | 6/30/13                                      Class Z Shares

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

<TABLE>
<CAPTION>
Average Annual Total Returns
(As of June 30, 2013)
--------------------------------------------------------------------------------
                  If                   If
Period            Held                 Redeemed
--------------------------------------------------------------------------------
<S>               <C>                  <C>
10 Years           6.78%                6.78%
5 Years            4.82                 4.82
1 Year            19.65                19.65
--------------------------------------------------------------------------------

<CAPTION>
Expense Ratio
(Per prospectus dated May 1, 2013)
--------------------------------------------------------------------------------
                  Gross                Net
--------------------------------------------------------------------------------
<S>               <C>                  <C>
                  0.87%                0.85%
--------------------------------------------------------------------------------
</TABLE>

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

Value of $10,000 Investment

<TABLE>
<CAPTION>
                  Pioneer Fund         Standard & Poor's 500 Index
<S>               <C>                  <C>
6/30/2003         $ 10,000             $10,000
6/30/2004         $ 11,814             $11,909
6/30/2005         $ 12,805             $12,662
6/30/2006         $ 14,393             $13,754
6/30/2007         $ 17,296             $16,584
6/30/2008         $ 15,232             $14,409
6/30/2009         $ 11,303             $10,634
6/30/2010         $ 12,742             $12,169
6/30/2011         $ 16,827             $15,902
6/30/2012         $ 16,110             $16,765
6/30/2013         $ 19,276             $20,216
</TABLE>

Call 1-800-225-6292 or visit us.pioneerinvestments.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.

Performance shown for periods prior to the inception of Class Z shares on April
30, 2007, reflects the NAV performance of the Fund's Class A shares. The
performance does not reflect differences in expenses, including the Rule 12b-1
fees applicable to Class A shares. Since fees for Class A shares are generally
higher than those of Class Z shares, the performance for Class Z shares prior to
their inception would have been higher than that shown. Class Z 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 net expense ratio reflects the contractual expense limitation currently in
effect through May 1, 2014, for Class Z shares. There can be no assurance that
Pioneer will extend the expense limitation beyond such time. Please 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.

14 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

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 Fund

Based on actual returns from January 1, 2013, through June 30, 2013.

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------
Share Class            A          B          C          R          Y          Z
-----------------------------------------------------------------------------------
<S>                <C>        <C>        <C>        <C>        <C>        <C>
Beginning Account  $1,000.00  $1,000.00  $1,000.00  $1,000.00  $1,000.00  $1,000.00
Value on 1/1/13
-----------------------------------------------------------------------------------
Ending Account     $1,137.80  $1,130.80  $1,133.50  $1,136.60  $1,139.90  $1,138.40
Value on 6/30/13
-----------------------------------------------------------------------------------
Expenses Paid      $    5.19  $   11.78  $    9.20  $    6.46  $    3.29  $    4.51
During Period*
-----------------------------------------------------------------------------------
</TABLE>

*    Expenses are equal to the Fund's annualized net expense ratio of 0.98%,
     2.23%, 1.74%, 1.22%, 0.62%, and 0.85% for Class A, Class B, Class C, Class
     R, Class Y and Class Z shares, respectively, multiplied by the average
     account value over the period, multiplied by 181/365 (to reflect the
     one-half year period).

                                   Pioneer Fund | Semiannual Report | 6/30/13 15
<PAGE>

Comparing Ongoing Fund Expenses (continued)

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 Fund

Based on a hypothetical 5% per year return before expenses, reflecting the
period from January 1, 2013, through June 30, 2013.

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------
Share Class            A          B          C          R          Y          Z
-----------------------------------------------------------------------------------
<S>                <C>        <C>        <C>        <C>        <C>        <C>
Beginning Account  $1,000.00  $1,000.00  $1,000.00  $1,000.00  $1,000.00  $1,000.00
Value on 1/1/13
-----------------------------------------------------------------------------------
Ending Account     $1,019.93  $1,013.74  $1,016.17  $1,018.74  $1,021.72  $1,020.58
Value on 6/30/13
-----------------------------------------------------------------------------------
Expenses Paid      $    4.91  $   11.13  $    8.70  $    6.11  $    3.11  $    4.26
During Period*
-----------------------------------------------------------------------------------
</TABLE>

*    Expenses are equal to the Fund's annualized net expense ratio of 0.98%,
     2.23%, 1.74%, 1.22%, 0.62%, and 0.85% for Class A, Class B, Class C, Class
     R, Class Y and Class Z shares, respectively, multiplied by the average
     account value over the period, multiplied by 181/365 (to reflect the
     one-half year period).

16 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

Schedule of Investments | 6/30/13 (unaudited)

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------------
Shares                                                                  Value
--------------------------------------------------------------------------------------
<S>             <C>                                                     <C>
                COMMON STOCKS -- 100.0%
                ENERGY -- 9.6%
                Oil & Gas Drilling -- 0.9%
      610,174   Ensco Plc                                               $   35,463,313
      147,315   Helmerich & Payne, Inc.                                      9,199,822
                                                                        --------------
                                                                        $   44,663,135
--------------------------------------------------------------------------------------
                Oil & Gas Equipment & Services -- 2.0%
      175,977   Cameron International Corp.*                            $   10,762,753
      173,621   FMC Technologies, Inc.*                                      9,667,217
      383,928   Halliburton Co.                                             16,017,476
      327,722   National Oilwell Varco, Inc.                                22,580,046
      486,724   Schlumberger, Ltd.                                          34,878,642
                                                                        --------------
                                                                        $   93,906,134
--------------------------------------------------------------------------------------
                Integrated Oil & Gas -- 1.4%
      481,441   Chevron Corp.                                           $   56,973,728
      134,876   Occidental Petroleum Corp.                                  12,034,985
                                                                        --------------
                                                                        $   69,008,713
--------------------------------------------------------------------------------------
                Oil & Gas Exploration & Production -- 4.1%
      494,344   Apache Corp.                                            $   41,440,858
      729,307   Cabot Oil & Gas Corp.                                       51,795,383
      520,932   ConocoPhillips                                              31,516,386
    1,112,362   Marathon Oil Corp.                                          38,465,478
      865,989   Southwestern Energy Co.*                                    31,634,578
                                                                        --------------
                                                                        $  194,852,683
--------------------------------------------------------------------------------------
                Oil & Gas Refining & Marketing -- 1.2%
      418,657   Marathon Petroleum Corp.*                               $   29,749,766
      451,596   Phillips 66                                                 26,603,520
                                                                        --------------
                                                                        $   56,353,286
                                                                        --------------
                Total Energy                                            $  458,783,951
--------------------------------------------------------------------------------------
                MATERIALS -- 2.9%
                Fertilizers & Agricultural Chemicals -- 0.9%
      196,182   Monsanto Co.                                            $   19,382,782
      396,778   The Mosaic Co.                                              21,350,624
                                                                        --------------
                                                                        $   40,733,406
--------------------------------------------------------------------------------------
                Industrial Gases -- 0.8%
      412,586   Airgas, Inc.                                            $   39,385,460
--------------------------------------------------------------------------------------
                Specialty Chemicals -- 1.0%
      565,016   Ecolab, Inc.                                            $   48,133,713
--------------------------------------------------------------------------------------
                Paper Products -- 0.2%
      232,084   International Paper Co.                                 $   10,283,642
                                                                        --------------
                Total Materials                                         $  138,536,221
--------------------------------------------------------------------------------------
</TABLE>

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

                                   Pioneer Fund | Semiannual Report | 6/30/13 17
<PAGE>

Schedule of Investments | 6/30/13 (unaudited) (continued)

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------------
Shares                                                                  Value
--------------------------------------------------------------------------------------
<S>             <C>                                                     <C>
                CAPITAL GOODS -- 9.2%
                Aerospace & Defense -- 1.9%
      209,914   Raytheon Co.                                            $   13,879,514
      841,108   United Technologies Corp.                                   78,172,578
                                                                        --------------
                                                                        $   92,052,092
--------------------------------------------------------------------------------------
                Construction & Engineering -- 0.6%
      847,311   KBR, Inc.                                               $   27,537,608
--------------------------------------------------------------------------------------
                Electrical Components & Equipment -- 0.3%
      169,655   Rockwell Automation, Inc.                               $   14,105,117
--------------------------------------------------------------------------------------
                Industrial Conglomerates -- 2.8%
      686,209   3M Co.                                                  $   75,036,954
    2,591,883   General Electric Co.                                        60,105,767
                                                                        --------------
                                                                        $  135,142,721
--------------------------------------------------------------------------------------
                Construction & Farm Machinery & Heavy Trucks -- 2.0%
      333,902   Cummins, Inc.                                           $   36,215,011
      301,924   Joy Global, Inc.                                            14,652,372
      798,943   PACCAR, Inc.                                                42,871,281
                                                                        --------------
                                                                        $   93,738,664
--------------------------------------------------------------------------------------
                Industrial Machinery -- 1.6%
      878,014   Ingersoll-Rand Plc                                      $   48,747,337
      395,111   SPX Corp.                                                   28,440,090
                                                                        --------------
                                                                        $   77,187,427
                                                                        --------------
                Total Capital Goods                                     $  439,763,629
--------------------------------------------------------------------------------------
                TRANSPORTATION -- 2.3%
                Air Freight & Logistics -- 0.5%
      267,887   United Parcel Service, Inc. (Class B)                   $   23,166,868
--------------------------------------------------------------------------------------
                Railroads -- 1.8%
      586,986   Norfolk Southern Corp.                                  $   42,644,533
      292,508   Union Pacific Corp.                                         45,128,134
                                                                        --------------
                                                                        $   87,772,667
                                                                        --------------
                Total Transportation                                    $  110,939,535
--------------------------------------------------------------------------------------
                AUTOMOBILES & COMPONENTS -- 2.4%
                Auto Parts & Equipment -- 1.1%
      260,003   BorgWarner, Inc.*                                       $   22,399,258
      844,254   Johnson Controls, Inc.                                      30,215,851
                                                                        --------------
                                                                        $   52,615,109
--------------------------------------------------------------------------------------
                Automobile Manufacturers -- 1.3%
    3,898,499   Ford Motor Co.                                          $   60,309,780
                                                                        --------------
                Total Automobiles & Components                          $  112,924,889
--------------------------------------------------------------------------------------
</TABLE>

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

18 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------------
Shares                                                                  Value
--------------------------------------------------------------------------------------
<S>             <C>                                                     <C>
                CONSUMER DURABLES & APPAREL -- 0.6%
                Apparel, Accessories & Luxury Goods -- 0.6%
      520,104   Coach, Inc.                                             $   29,692,737
                                                                        --------------
                Total Consumer Durables & Apparel                       $   29,692,737
--------------------------------------------------------------------------------------
                CONSUMER SERVICES -- 1.6%
                Restaurants -- 1.6%
      428,756   McDonald's Corp.                                        $   42,446,844
      499,578   Starbucks Corp.                                             32,717,363
                                                                        --------------
                                                                        $   75,164,207
                                                                        --------------
                Total Consumer Services                                 $   75,164,207
--------------------------------------------------------------------------------------
                MEDIA -- 4.5%
                Cable & Satellite -- 0.3%
      363,722   Comcast Corp.                                           $   15,232,677
--------------------------------------------------------------------------------------
                Movies & Entertainment -- 1.8%
    1,115,002   The Walt Disney Co.                                     $   70,412,376
      282,012   Time Warner, Inc.                                           16,305,934
                                                                        --------------
                                                                        $   86,718,310
--------------------------------------------------------------------------------------
                Publishing -- 2.4%
    2,784,250   John Wiley & Sons, Inc.+                                $  111,620,582
                                                                        --------------
                Total Media                                             $  213,571,569
--------------------------------------------------------------------------------------
                RETAILING -- 4.8%
                Department Stores -- 1.4%
      779,334   Macy's, Inc.                                            $   37,408,032
      466,175   Nordstrom, Inc.                                             27,942,530
                                                                        --------------
                                                                        $   65,350,562
--------------------------------------------------------------------------------------
                General Merchandise Stores -- 1.0%
      681,185   Target Corp.                                            $   46,906,399
--------------------------------------------------------------------------------------
                Apparel Retail -- 1.7%
      555,490   Ross Stores, Inc.                                       $   36,001,307
      879,780   TJX Companies, Inc.                                         44,041,787
                                                                        --------------
                                                                        $   80,043,094
--------------------------------------------------------------------------------------
                Home Improvement Retail -- 0.7%
      386,580   Lowe's Companies, Inc.                                  $   15,811,122
      262,492   The Home Depot, Inc.                                        20,335,255
                                                                        --------------
                                                                        $   36,146,377
                                                                        --------------
                Total Retailing                                         $  228,446,432
--------------------------------------------------------------------------------------
                FOOD & STAPLES RETAILING -- 2.7%
                Drug Retail -- 2.3%
      730,583   CVS Caremark Corp.                                      $   41,774,736
    1,568,351   Walgreen Co.                                                69,321,114
                                                                        --------------
                                                                        $  111,095,850
--------------------------------------------------------------------------------------
</TABLE>

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

                                   Pioneer Fund | Semiannual Report | 6/30/13 19
<PAGE>

Schedule of Investments | 6/30/13 (unaudited) (continued)

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------------
Shares                                                                  Value
--------------------------------------------------------------------------------------
<S>             <C>                                                     <C>
                Hypermarkets & Super Centers -- 0.4%
      231,200   Wal-Mart Stores, Inc.                                   $   17,222,088
                                                                        --------------
                Total Food & Staples Retailing                          $  128,317,938
--------------------------------------------------------------------------------------
                FOOD, BEVERAGE & TOBACCO -- 6.1%
                Soft Drinks -- 1.0%
      350,185   Coca-Cola Enterprises, Inc.                             $   12,312,505
      399,721   Dr. Pepper Snapple Group, Inc.                              18,359,186
      228,650   PepsiCo, Inc.                                               18,701,284
                                                                        --------------
                                                                        $   49,372,975
--------------------------------------------------------------------------------------
                Packaged Foods & Meats -- 5.1%
      524,701   Campbell Soup Co.                                       $   23,501,358
      752,122   General Mills, Inc.                                         36,500,481
      402,759   Kraft Foods Group, Inc.*                                    22,502,145
    1,208,380   Mondelez International, Inc.                                34,475,081
    1,394,463   The Hershey Co.                                            124,497,656
                                                                        --------------
                                                                        $  241,476,721
                                                                        --------------
                Total Food, Beverage & Tobacco                          $  290,849,696
--------------------------------------------------------------------------------------
                HOUSEHOLD & PERSONAL PRODUCTS -- 3.0%
                Household Products -- 3.0%
    1,745,703   Colgate-Palmolive Co.                                   $  100,011,325
      232,722   The Clorox Co.                                              19,348,507
      305,946   The Procter & Gamble Co.                                    23,554,783
                                                                        --------------
                                                                        $  142,914,615
                                                                        --------------
                Total Household & Personal Products                     $  142,914,615
--------------------------------------------------------------------------------------
                HEALTH CARE EQUIPMENT & SERVICES -- 6.8%
                Health Care Equipment -- 5.4%
    1,157,229   Abbott Laboratories, Inc.                               $   40,364,148
      441,686   Baxter International, Inc.                                  30,595,589
      490,372   Becton Dickinson and Co.                                    48,463,465
      682,204   Covidien Plc                                                42,869,699
      690,994   CR Bard, Inc.                                               75,097,228
    1,878,153   Smith & Nephew Plc                                          20,996,530
                                                                        --------------
                                                                        $  258,386,659
--------------------------------------------------------------------------------------
                Health Care Distributors -- 0.1%
      156,891   Cardinal Health, Inc.                                   $    7,405,255
--------------------------------------------------------------------------------------
                Health Care Services -- 0.7%
      171,463   DaVita HealthCare Partners, Inc.*                       $   20,712,730
      185,873   Express Scripts Holding Co.*                                11,466,505
                                                                        --------------
                                                                        $   32,179,235
--------------------------------------------------------------------------------------
</TABLE>

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

20 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------------
Shares                                                                  Value
--------------------------------------------------------------------------------------
<S>             <C>                                                     <C>
                Managed Health Care -- 0.6%
      467,109   Aetna, Inc.                                             $   29,680,106
                                                                        --------------
                Total Health Care Equipment & Services                  $  327,651,255
--------------------------------------------------------------------------------------
                PHARMACEUTICALS, BIOTECHNOLOGY & LIFE SCIENCES -- 8.6%
                Biotechnology -- 2.3%
      480,715   Amgen, Inc.                                             $   47,427,342
      329,194   Celgene Corp.*                                              38,486,071
      436,506   Gilead Sciences, Inc.*                                      22,353,472
                                                                        --------------
                                                                        $  108,266,885
--------------------------------------------------------------------------------------
                Pharmaceuticals -- 5.8%
    1,157,229   AbbVie, Inc.                                            $   47,839,847
      375,418   Eli Lilly & Co.                                             18,440,532
    1,034,862   Johnson & Johnson Co.                                       88,853,251
      565,816   Merck & Co., Inc.                                           26,282,153
    2,103,010   Pfizer, Inc.                                                58,905,310
    1,200,462   Zoetis, Inc.                                                37,082,271
                                                                        --------------
                                                                        $  277,403,364
--------------------------------------------------------------------------------------
                Life Sciences Tools & Services -- 0.5%
      280,933   Thermo Fisher Scientific, Inc.                          $   23,775,360
                                                                        --------------
                Total Pharmaceuticals, Biotechnology & Life Sciences    $  409,445,609
--------------------------------------------------------------------------------------
                BANKS -- 6.2%
                Diversified Banks -- 3.9%
      251,309   Canadian Imperial Bank of Commerce                      $   17,855,127
    1,688,984   US Bancorp                                                  61,056,772
    2,643,919   Wells Fargo & Co.                                          109,114,537
                                                                        --------------
                                                                        $  188,026,436
--------------------------------------------------------------------------------------
                Regional Banks -- 2.3%
    1,961,836   KeyCorp                                                 $   21,658,669
    1,206,600   The PNC Financial Services Group, Inc.                      87,985,272
                                                                        --------------
                                                                        $  109,643,941
                                                                        --------------
                Total Banks                                             $  297,670,377
--------------------------------------------------------------------------------------
                DIVERSIFIED FINANCIALS -- 7.0%
                Other Diversified Financial Services -- 3.0%
    2,335,074   Bank of America Corp.                                   $   30,029,052
    1,347,969   Citigroup, Inc.                                             64,662,073
      880,662   JPMorgan Chase & Co.                                        46,490,147
                                                                        --------------
                                                                        $  141,181,272
--------------------------------------------------------------------------------------
                Consumer Finance -- 1.4%
      423,417   American Express Co.                                    $   31,654,655
      760,108   Discover Financial Services, Inc.                           36,211,545
                                                                        --------------
                                                                        $   67,866,200
--------------------------------------------------------------------------------------
</TABLE>

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

                                   Pioneer Fund | Semiannual Report | 6/30/13 21
<PAGE>

Schedule of Investments | 6/30/13 (unaudited) (continued)

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------------
Shares                                                                  Value
--------------------------------------------------------------------------------------
<S>             <C>                                                         <C>
                Asset Management & Custody Banks -- 2.2%
      254,915   Franklin Resources, Inc.                                $   34,673,538
      734,025   Invesco, Ltd.                                               23,341,995
      663,562   T. Rowe Price Group, Inc.                                   48,539,560
                                                                        --------------
                                                                        $  106,555,093
--------------------------------------------------------------------------------------
                Investment Banking & Brokerage -- 0.4%
      120,554   The Goldman Sachs Group, Inc.                           $   18,233,792
                                                                        --------------
                Total Diversified Financials                            $  333,836,357
--------------------------------------------------------------------------------------
                INSURANCE -- 3.3%
                Life & Health Insurance -- 0.8%
      648,578   Aflac, Inc.                                             $   37,695,353
--------------------------------------------------------------------------------------
                Property & Casualty Insurance -- 2.5%
      980,048   The Chubb Corp.                                         $   82,961,063
      460,339   The Travelers Companies, Inc.                               36,790,293
                                                                        --------------
                                                                        $  119,751,356
                                                                        --------------
                Total Insurance                                         $  157,446,709
--------------------------------------------------------------------------------------
                SOFTWARE & SERVICES -- 10.7%
                Internet Software & Services -- 2.0%
      593,157   eBay, Inc.*                                             $   30,678,080
      722,505   Facebook, Inc.*                                             17,961,474
       50,616   Google, Inc.*                                               44,560,808
                                                                        --------------
                                                                        $   93,200,362
--------------------------------------------------------------------------------------
                IT Consulting & Other Services -- 1.1%
      281,596   International Business Machines Corp.                   $   53,815,812
--------------------------------------------------------------------------------------
                Data Processing & Outsourced Services -- 3.1%
      808,447   Automatic Data Processing, Inc.                         $   55,669,660
      347,315   DST Systems, Inc.                                           22,690,089
      319,332   Fiserv, Inc.*                                               27,912,810
       36,098   Mastercard, Inc.                                            20,738,301
      127,519   Visa, Inc.                                                  23,304,097
                                                                        --------------
                                                                        $  150,314,957
--------------------------------------------------------------------------------------
                Application Software -- 0.9%
      796,123   Adobe Systems, Inc.*                                    $   36,271,364
      358,721   Nuance Communications, Inc.*                                 6,593,292
                                                                        --------------
                                                                        $   42,864,656
--------------------------------------------------------------------------------------
                Systems Software -- 3.6%
    2,967,057   Microsoft Corp.                                         $  102,452,478
    1,351,351   Oracle Corp.                                                41,513,503
    1,303,934   Symantec Corp.                                              29,299,397
                                                                        --------------
                                                                        $  173,265,378
                                                                        --------------
                Total Software & Services                               $  513,461,165
--------------------------------------------------------------------------------------
</TABLE>

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

22 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------------
Shares                                                                  Value
--------------------------------------------------------------------------------------
<S>             <C>                                                     <C>
                TECHNOLOGY HARDWARE & EQUIPMENT -- 3.4%
                Communications Equipment -- 1.3%
    1,575,131   Cisco Systems, Inc.                                     $   38,291,435
      128,696   F5 Networks, Inc.*                                           8,854,285
      291,744   Motorola Solutions, Inc.                                    16,842,381
        1,919   Palo Alto Networks, Inc.*                                       80,905
                                                                        --------------
                                                                        $   64,069,006
--------------------------------------------------------------------------------------
                Computer Hardware -- 1.7%
      209,925   Apple, Inc.                                             $   83,147,094
--------------------------------------------------------------------------------------
                Computer Storage & Peripherals -- 0.4%
      748,441   EMC Corp.                                               $   17,678,176
                                                                        --------------
                Total Technology Hardware & Equipment                   $  164,894,276
--------------------------------------------------------------------------------------
                SEMICONDUCTORS & SEMICONDUCTOR EQUIPMENT -- 3.1%
                Semiconductor Equipment -- 0.4%
      269,598   ASML Holding NV (A.D.R.)                                $   21,325,202
--------------------------------------------------------------------------------------
                Semiconductors -- 2.7%
    1,304,146   Analog Devices, Inc.                                    $   58,764,819
      805,865   Intel Corp.                                                 19,518,050
      469,779   Maxim Integrated Products, Inc.                             13,050,461
      910,090   Xilinx, Inc.                                                36,048,665
                                                                        --------------
                                                                        $  127,381,995
                                                                        --------------
                Total Semiconductors & Semiconductor Equipment          $  148,707,197
--------------------------------------------------------------------------------------
                TELECOMMUNICATION SERVICES -- 0.8%
                Integrated Telecommunication Services -- 0.8%
      787,271   Verizon Communications, Inc.                            $   39,631,222
                                                                        --------------
                Total Telecommunication Services                        $   39,631,222
--------------------------------------------------------------------------------------
                UTILITIES -- 0.4%
                Electric Utilities -- 0.4%
      467,109   American Electric Power Co., Inc.                       $   20,917,141
                                                                        --------------
                Total Utilities                                         $   20,917,141
--------------------------------------------------------------------------------------
                TOTAL COMMON STOCKS
                (Cost $2,915,210,666)                                   $4,783,566,727
--------------------------------------------------------------------------------------
                TOTAL INVESTMENT IN SECURITIES -- 100.0%
                (Cost $2,915,210,666) (a)                               $4,783,566,727
--------------------------------------------------------------------------------------
                OTHER ASSETS & LIABILITIES -- 0.0%                      $   (1,267,942)
--------------------------------------------------------------------------------------
                TOTAL NET ASSETS -- 100.0%                              $4,782,298,785
======================================================================================
</TABLE>

*        Non-income producing security.

+        Investment held by the Fund representing 5% or more of the outstanding
         voting stock of such company. See Notes to Financial Statements --
         Note 6.

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

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

                                   Pioneer Fund | Semiannual Report | 6/30/13 23
<PAGE>

Schedule of Investments | 6/30/13 (unaudited) (continued)

(a)  At June 30, 2013, the net unrealized gain on investments based
     on cost for federal income tax purposes of $2,919,943,397 was as
     follows:

<TABLE>
<CAPTION>
<S>                                                                    <C>
       Aggregate gross unrealized gain for all investments in which
         there is an excess of value over tax cost                     $ 1,913,834,370

       Aggregate gross unrealized loss for all investments in which
         there is an excess of tax cost over value                         (50,211,040)
                                                                       ---------------
       Net unrealized gain                                             $ 1,863,623,330
                                                                       ===============
</TABLE>

Purchases and sales of securities (excluding temporary cash investments) for the
six months ended June 30, 2013 aggregated $202,418,775 and $574,276,212,
respectively.

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.

Generally, equity securities are categorized as Level 1, fixed income securities
and senior loans as Level 2 and securities valued using fair value methods
(other than prices supplied by independent pricing services) as Level 3. See
Notes to Financial Statements -- Note 1A.

The following is a summary of the inputs used as of June 30, 2013, in valuing
the Fund's investments:

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------
                        Level 1          Level 2     Level 3     Total
--------------------------------------------------------------------------------
<S>                     <C>              <C>         <C>         <C>
Common Stocks           $4,783,566,727   $      --   $      --   $4,783,566,727
--------------------------------------------------------------------------------
Total                   $4,783,566,727   $      --   $      --   $4,783,566,727
================================================================================
</TABLE>

During the six months ended June 30, 2013, there were no transfers between
Levels 1, 2 and 3.

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

24 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

Statement of Assets and Liabilities | 6/30/13 (unaudited)

<TABLE>
<CAPTION>
<S>                                                                      <C>
ASSETS:
  Investment in securities of unaffiliated issuers, at value
     (cost $2,909,356,652)                                               $4,671,946,145
  Investment in securities of affiliated issuers, at value
     (cost $5,854,014)                                                      111,620,582
----------------------------------------------------------------------------------------
     Total investment in securities, at value (cost $2,915,210,666)      $4,783,566,727
  Cash                                                                      123,115,862
  Receivables --
     Investment securities sold                                              31,894,837
     Fund shares sold                                                         1,066,125
     Dividends                                                                5,183,798
  Prepaid expenses                                                              125,135
----------------------------------------------------------------------------------------
        Total assets                                                     $4,944,952,484
----------------------------------------------------------------------------------------
LIABILITIES:
  Payables --
     Fund shares repurchased                                             $  158,361,625
     Dividends                                                                   13,551
  Due to advisor                                                                    193
  Due to affiliates                                                           4,083,870
  Accrued expenses                                                              194,460
----------------------------------------------------------------------------------------
         Total liabilities                                               $  162,653,699
----------------------------------------------------------------------------------------
NET ASSETS:
  Paid-in capital                                                        $2,553,247,001
  Undistributed net investment income                                           768,187
  Accumulated net realized gain on investments and foreign
     currency transactions                                                  359,928,287
  Net unrealized appreciation on investments                              1,868,356,061
  Net unrealized depreciation on forward foreign currency contracts and
     other assets and liabilities denominated in foreign currencies                (751)
----------------------------------------------------------------------------------------
        Total net assets                                                 $4,782,298,785
----------------------------------------------------------------------------------------
NET ASSET VALUE PER SHARE:
(No par value, unlimited number of shares authorized)
  Class A (based on $4,142,642,597/112,744,208 shares)                   $        36.74
  Class B (based on $30,053,519/850,171 shares)                          $        35.35
  Class C (based on $142,747,945/4,116,436 shares)                       $        34.68
  Class R (based on $88,380,893/2,399,776 shares)                        $        36.83
  Class Y (based on $377,389,419/10,216,875 shares)                      $        36.94
  Class Z (based on $1,084,412/29,436 shares)                            $        36.84
MAXIMUM OFFERING PRICE:
  Class A ($36.74 (divided by) 94.25%)                                   $        38.98
========================================================================================
</TABLE>

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

                                   Pioneer Fund | Semiannual Report | 6/30/13 25
<PAGE>

Statement of Operations (unaudited)

For the Six Months Ended 6/30/13

<TABLE>
<CAPTION>
<S>                                                             <C>            <C>
INVESTMENT INCOME:
  Dividends (net of foreign taxes withheld of $98,666 and
      including income from affiliated issuers of $1,381,927)   $ 48,713,060
  Interest                                                             1,992
--------------------------------------------------------------------------------------------
            Total investment income                                            $ 48,715,052
--------------------------------------------------------------------------------------------
EXPENSES:
  Management fees
     Basic fee                                                  $ 11,630,119
     Performance adjustment                                           57,066
  Transfer agent fees and expenses
     Class A                                                       3,172,298
     Class B                                                          96,486
     Class C                                                          57,918
     Class R                                                           5,974
     Class Y                                                          24,309
     Class Z                                                             672
  Distribution fees
     Class A                                                       5,112,147
     Class B                                                         162,761
     Class C                                                         711,655
     Class R                                                         256,969
  Shareholder communications expense                               1,429,010
  Administrative reimbursement                                       683,936
  Custodian fees                                                      22,482
  Registration fees                                                   69,423
  Professional fees                                                   95,297
  Printing expense                                                    19,566
  Fees and expenses of nonaffiliated Trustees                         89,670
  Miscellaneous                                                      165,080
--------------------------------------------------------------------------------------------
     Total expenses                                                            $ 23,862,838
     Less fees waived and expenses reimbursed
        by Pioneer Investment Management, Inc.                                         (155)
--------------------------------------------------------------------------------------------
     Net expenses                                                              $ 23,862,683
--------------------------------------------------------------------------------------------
        Net investment income                                                  $ 24,852,369
--------------------------------------------------------------------------------------------
REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS
AND FOREIGN CURRENCY TRANSACTIONS:
  Net realized gain (loss) on:
     Investments                                                $258,728,250
     Class action                                                      2,719
     Forward foreign currency contracts and other assets
        and liabilities denominated in foreign currencies             (3,941)  $258,727,028
--------------------------------------------------------------------------------------------
  Change in net unrealized appreciation (depreciation) on:
     Investments                                                $345,863,241
     Forward foreign currency contracts and other assets and
        liabilities denominated in foreign currencies                   (450)  $345,862,791
--------------------------------------------------------------------------------------------
  Net gain on investments and foreign currency transactions                    $604,589,819
--------------------------------------------------------------------------------------------
  Net increase in net assets resulting from operations                         $629,442,188
============================================================================================
</TABLE>

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

26 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

Statements of Changes in Net Assets

<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------
                                                            Six Months
                                                            Ended            Year
                                                            6/30/13          Ended
                                                            (unaudited)      12/31/12
----------------------------------------------------------------------------------------------
<S>                                                         <C>              <C>
FROM OPERATIONS:
Net investment income                                       $   24,852,369   $     75,360,813
Net realized gain on investments and foreign
  currency transactions                                        258,727,028      1,351,637,529
Change in net unrealized appreciation (depreciation) on
  investments and foreign currency transactions                345,862,791       (864,894,284)
----------------------------------------------------------------------------------------------
      Net increase in net assets resulting from operations  $  629,442,188   $    562,104,058
----------------------------------------------------------------------------------------------
DISTRIBUTIONS TO SHAREOWNERS:
Net investment income:
      Class A ($0.18 and $0.49 per share, respectively)     $  (20,533,312)  $    (51,818,663)
      Class B ($0.00 and $0.06 per share, respectively)                 --            (65,670)
      Class C ($0.05 and $0.21 per share, respectively)           (209,833)          (856,844)
      Class R ($0.12 and $0.36 per share, respectively)           (328,775)        (1,075,524)
      Class Y ($0.23 and $0.62 per share, respectively)         (3,412,410)       (21,729,817)
      Class Z ($0.19 and $0.55 per share, respectively)             (5,164)           (19,468)
Net realized gain:
      Class A ($0.00 and $9.30 per share, respectively)                 --       (874,235,166)
      Class B ($0.00 and $9.30 per share, respectively)                 --         (8,048,440)
      Class C ($0.00 and $9.30 per share, respectively)                 --        (32,315,737)
      Class R ($0.00 and $9.30 per share, respectively)                 --        (23,535,006)
      Class Y ($0.00 and $9.30 per share, respectively)                 --       (123,297,278)
      Class Z ($0.00 and $9.30 per share, respectively)                 --           (282,644)
----------------------------------------------------------------------------------------------
           Total distributions to shareowners               $  (24,489,494)  $ (1,137,280,257)
----------------------------------------------------------------------------------------------
FROM FUND SHARE TRANSACTIONS:
Net proceeds from sale or exchange of shares                $  127,611,984   $    411,985,287
Reinvestment of distributions                                   22,934,653      1,051,852,192
Cost of shares repurchased                                    (601,686,778)    (2,420,885,932)
----------------------------------------------------------------------------------------------
      Net decrease in net assets resulting from
          Fund share transactions                           $ (451,140,141)  $   (957,048,453)
----------------------------------------------------------------------------------------------
      Net increase (decrease) in net assets                 $  153,812,553   $ (1,532,224,652)
NET ASSETS:
Beginning of period                                          4,628,486,232      6,160,710,884
----------------------------------------------------------------------------------------------
End of period                                               $4,782,298,785   $  4,628,486,232
----------------------------------------------------------------------------------------------
Undistributed net investment income                         $      768,187   $        405,312
==============================================================================================
</TABLE>

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

                                   Pioneer Fund | Semiannual Report | 6/30/13 27
<PAGE>

Statements of Changes in Net Assets (continued)

<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------------
                                 '13 Shares     '13 Amount
                                 (unaudited)    (unaudited)      '12 Shares    '12 Amount
------------------------------------------------------------------------------------------------
<S>                              <C>           <C>               <C>           <C>
Class A
Shares sold                       2,340,737    $   83,379,784      3,889,445   $    152,363,607
Reinvestment of distributions       539,662        19,508,982     27,127,422        873,392,740
Less shares repurchased          (8,446,438)     (301,297,181)   (15,682,814)      (617,318,145)
------------------------------------------------------------------------------------------------
      Net increase (decrease)    (5,566,039)   $ (198,408,415)    15,334,053   $    408,438,202
------------------------------------------------------------------------------------------------
Class B
Shares sold or exchanged              5,581    $      196,191         19,821   $        735,864
Reinvestment of distributions            --                --        259,898          7,970,433
Less shares repurchased            (234,655)       (8,073,456)      (481,081)       (18,904,140)
------------------------------------------------------------------------------------------------
      Net decrease                 (229,074)   $   (7,877,265)      (201,362)  $    (10,197,843)
------------------------------------------------------------------------------------------------
Class C
Shares sold                         212,154    $    7,150,043        785,265   $     26,404,850
Reinvestment of distributions         3,629           123,663        631,628         19,079,617
Less shares repurchased            (531,118)      (17,833,386)      (963,838)       (36,659,228)
------------------------------------------------------------------------------------------------
      Net increase (decrease)      (315,335)   $  (10,559,680)       453,055   $      8,825,239
------------------------------------------------------------------------------------------------
Class R
Shares sold                         150,954    $    5,408,665        327,180   $     12,947,423
Reinvestment of distributions         8,920           322,900        753,577         24,238,053
Less shares repurchased            (960,236)      (34,902,371)    (1,174,542)       (47,279,595)
------------------------------------------------------------------------------------------------
      Net decrease                 (800,362)   $  (29,170,806)       (93,785)  $    (10,094,119)
------------------------------------------------------------------------------------------------
Class Y
Shares sold                         881,702    $   31,279,084      5,371,099   $    218,606,953
Reinvestment of distributions        81,777         2,973,944      3,829,183        126,870,840
Less shares repurchased          (6,522,815)     (239,269,926)   (41,428,056)    (1,699,742,251)
------------------------------------------------------------------------------------------------
      Net decrease               (5,559,336)   $ (205,016,898)   (32,227,774)  $ (1,354,264,458)
------------------------------------------------------------------------------------------------
Class Z
Shares sold                           5,204    $      198,217         22,340   $        926,590
Reinvestment of distributions           142             5,164          9,301            300,509
Less shares repurchased              (9,076)         (310,458)       (25,420)          (982,573)
------------------------------------------------------------------------------------------------
      Net increase (decrease)        (3,730)   $     (107,077)         6,221   $        244,526
------------------------------------------------------------------------------------------------
</TABLE>

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

28 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

Financial Highlights

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------------------------------------------
                                                        Six Months
                                                        Ended         Year        Year         Year        Year        Year
                                                        6/30/13       Ended       Ended        Ended       Ended       Ended
                                                        (unaudited)   12/31/12    12/31/11     12/31/10    12/31/09    12/31/08
-----------------------------------------------------------------------------------------------------------------------------------
<S>                                                     <C>           <C>         <C>          <C>         <C>         <C>
Class A
Net asset value, beginning of period                    $    32.45    $    38.62  $    40.96   $    35.72  $    29.13  $    46.32
-----------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations:
   Net investment income                                $     0.18    $     0.48  $     0.46   $     0.35  $     0.40  $     0.45
   Net realized and unrealized gain (loss) on
      investments                                             4.29          3.14       (2.34)        5.22        6.59      (16.33)
-----------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations      $     4.47    $     3.62  $    (1.88)  $     5.57  $     6.99  $   (15.88)
-----------------------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
   Net investment income                                     (0.18)        (0.49)      (0.46)       (0.33)      (0.39)      (0.45)
   Net realized gain                                            --         (9.30)         --           --          --       (0.86)
   Tax return of capital                                        --            --          --           --       (0.01)         --
-----------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value              $     4.29    $    (6.17) $    (2.34)  $     5.24  $     6.59  $   (17.19)
-----------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                          $    36.74    $    32.45  $    38.62   $    40.96  $    35.72  $    29.13
===================================================================================================================================
Total return*                                                13.78%         9.90%      (4.59)%      15.72%      24.24%     (34.38)%
Ratio of total expenses to average net assets+                0.98%**       1.01%       1.09%        1.16%       1.23%       1.19%
Ratio of net investment income to average net assets+         1.01%**       1.24%       1.11%        0.94%       1.31%       1.11%
Portfolio turnover rate                                          8%**         41%         10%          10%         12%         11%
Net assets, end of period (in thousands)                $4,142,643    $3,839,361  $3,976,835   $4,526,447  $4,323,282  $3,767,132
Ratios with reductions for fees paid indirectly:
   Total expenses                                             0.98%**       1.01%       1.09%        1.16%       1.23%       1.18%
   Net investment income                                      1.01%**       1.24%       1.11%        0.94%       1.31%       1.12%
===================================================================================================================================
</TABLE>

*    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.

+    Ratio with no reduction for fees paid indirectly.

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

                                   Pioneer Fund | Semiannual Report | 6/30/13 29
<PAGE>

Financial Highlights (continued)

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------------------------------------------
                                                                Six Months
                                                                Ended        Year       Year       Year       Year       Year
                                                                6/30/13      Ended      Ended      Ended      Ended      Ended
                                                                (unaudited)  12/31/12   12/31/11   12/31/10   12/31/09   12/31/08
-----------------------------------------------------------------------------------------------------------------------------------
<S>                                                             <C>          <C>        <C>        <C>        <C>        <C>
Class B
Net asset value, beginning of period                            $ 31.26      $ 37.60    $ 39.86    $ 34.82    $  28.43   $  45.11
-----------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations:
   Net investment income (loss)                                 $ (0.05)     $ (0.01)   $ (0.03)   $ (0.06)   $   0.06   $   0.07
   Net realized and unrealized gain (loss) on investments          4.14         3.03      (2.23)      5.10        6.41     (15.89)
-----------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations              $  4.09      $  3.02    $ (2.26)   $  5.04    $   6.47   $ (15.82)
-----------------------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
   Net investment income                                             --(a)     (0.06)        --(a)      --       (0.07)        --
   Net realized gain                                                 --(a)     (9.30)        --(a)      --          --      (0.86)
   Tax return of capital                                             --           --         --         --       (0.01)        --
-----------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                      $  4.09      $ (6.34)   $ (2.26)   $  5.04    $   6.39   $ (16.68)
-----------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                                  $ 35.35      $ 31.26    $ 37.60    $ 39.86    $  34.82   $  28.43
===================================================================================================================================
Total return*                                                     13.08%        8.55%     (5.67)%    14.47%      22.84%    (34.99)%
Ratio of total expenses to average net assets+                     2.23%**      2.27%      2.24%      2.24%       2.34%      2.13%
Ratio of net investment income (loss) to average net assets+      (0.25)%**    (0.03)%    (0.06)%    (0.14)%      0.23%      0.14%
Portfolio turnover rate                                               8%**        41%        10%        10%         12%        11%
Net assets, end of period (in thousands)                        $30,054      $33,737    $48,149    $82,547    $110,976   $134,094
Ratios with reduction for fees paid indirectly:
    Total expenses                                                 2.23%**      2.27%      2.24%      2.24%       2.34%      2.12%
    Net investment income (loss)                                  (0.25)%**    (0.03)%    (0.06)%    (0.14)%      0.23%      0.15%
===================================================================================================================================
</TABLE>

*    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.

+    Ratio with no reduction for fees paid indirectly.

(a)  Dividends and/or capital gain distributions may continue to be reinvested
     in Class B shares, and shareholders may exchange their Class B shares for
     Class B shares of other Pioneer Funds, as permitted by existing exchange
     privileges.

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

30 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

<TABLE>
<CAPTION>
-------------------------------------------------------------------------------------------------------------------------------
                                                           Six Months
                                                           Ended        Year       Year        Year       Year       Year
                                                           6/30/13      Ended      Ended       Ended      Ended      Ended
                                                           (unaudited)  12/31/12   12/31/11    12/31/10   12/31/09   12/31/08
-------------------------------------------------------------------------------------------------------------------------------
<S>                                                        <C>          <C>        <C>         <C>        <C>        <C>
Class C
Net asset value, beginning of period                       $  30.64     $  36.99   $  39.26    $  34.26   $  27.96   $  44.55
-------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations:
   Net investment income                                   $   0.04     $   0.17   $   0.13    $   0.05   $   0.16   $   0.13
   Net realized and unrealized gain (loss) on investments      4.05         2.99      (2.23)       5.01       6.31     (15.70)
-------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations         $   4.09     $   3.16   $  (2.10)   $   5.06   $   6.47   $ (15.57)
-------------------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
   Net investment income                                      (0.05)       (0.21)     (0.17)      (0.06)     (0.16)     (0.16)
   Net realized gain                                             --        (9.30)        --          --         --      (0.86)
   Tax return of capital                                         --           --         --          --      (0.01)        --
-------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                 $   4.04     $  (6.35)  $  (2.27)   $   5.00   $   6.30   $ (16.59)
-------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                             $  34.68     $  30.64   $  36.99    $  39.26   $  34.26   $  27.96
===============================================================================================================================
Total return*                                                 13.35%        9.06%     (5.33)%     14.80%     23.28%    (34.91)%
Ratio of total expenses to average net assets+                 1.74%**      1.80%      1.87%       1.96%      1.99%      1.97%
Ratio of net investment income to average net assets+          0.25%**      0.45%      0.33%       0.14%      0.56%      0.32%
Portfolio turnover rate                                           8%**        41%        10%         10%        12%        11%
Net assets, end of period (in thousands)                   $142,748     $135,811   $147,166    $177,540   $178,807   $169,362
Ratios with reduction for fees paid indirectly:
   Total expenses                                              1.74%**      1.80%      1.87%       1.96%      1.99%      1.97%
   Net investment income                                       0.25%**      0.45%      0.33%       0.14%      0.56%      0.32%
===============================================================================================================================
</TABLE>

*    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.

+    Ratio with no reduction for fees paid indirectly.

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

                                   Pioneer Fund | Semiannual Report | 6/30/13 31
<PAGE>

Financial Highlights (continued)

<TABLE>
<CAPTION>
-------------------------------------------------------------------------------------------------------------------------------
                                                           Six Months
                                                           Ended       Year       Year        Year       Year       Year
                                                           6/30/13     Ended      Ended       Ended      Ended      Ended
                                                           (unaudited) 12/31/12   12/31/11    12/31/10   12/31/09   12/31/08
-------------------------------------------------------------------------------------------------------------------------------
<S>                                                        <C>         <C>        <C>         <C>        <C>        <C>
Class R
Net asset value, beginning of period                       $ 32.51     $  38.67   $  41.00    $  35.76   $  29.17   $  46.37
-------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations:
   Net investment income                                   $  0.15     $   0.36   $   0.34    $   0.22   $   0.33   $   0.40
   Net realized and unrealized gain (loss) on investments     4.29         3.14      (2.33)       5.23       6.58     (16.35)
-------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations         $  4.44     $   3.50   $  (1.99)   $   5.45   $   6.91   $ (15.95)
-------------------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
   Net investment income                                     (0.12)       (0.36)     (0.34)      (0.21)     (0.31)     (0.39)
   Net realized gain                                            --        (9.30)         --         --         --      (0.86)
   Tax return of capital                                        --           --          --         --      (0.01)        --
-------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                 $  4.32     $  (6.16)  $  (2.33)   $   5.24   $   6.59   $ (17.20)
-------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                             $ 36.83     $  32.51   $  38.67    $  41.00   $  35.76   $  29.17
===============================================================================================================================
Total return*                                                13.66%        9.57%     (4.85)%     15.31%     23.94%    (34.46)%
Ratio of total expenses to average net assets+                1.22%**      1.33%      1.38%       1.50%      1.45%      1.32%
Ratio of net investment income to average net assets+         0.76%**      0.92%      0.83%       0.60%      1.07%      0.99%
Portfolio turnover rate                                          8%**        41%        10%         10%        12%        11%
Net assets, end of period (in thousands)                   $88,381     $104,042   $127,377    $137,683   $121,773   $102,070
Ratios with reduction for fees paid indirectly:
   Total expenses                                             1.22%**      1.33%      1.38%       1.50%      1.45%      1.32%
   Net investment income                                      0.76%**      0.92%      0.83%       0.60%      1.07%      0.99%
===============================================================================================================================
</TABLE>

*    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.

+    Ratio with no reduction for fees paid indirectly.

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

32 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------------------------------------------
                                                           Six Months
                                                           Ended        Year      Year         Year         Year         Year
                                                           6/30/13      Ended     Ended        Ended        Ended        Ended
                                                           (unaudited)  12/31/12  12/31/11     12/31/10     12/31/09     12/31/08
-----------------------------------------------------------------------------------------------------------------------------------
<S>                                                        <C>          <C>       <C>          <C>          <C>          <C>
Class Y
Net asset value, beginning of period                       $  32.61     $  38.75  $    41.09   $    35.84   $    29.22   $  46.45
-----------------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations:
   Net investment income                                   $   0.25     $   0.75  $     0.60   $     0.49   $     0.52   $   0.61
   Net realized and unrealized gain (loss) on investments      4.31         3.03       (2.34)        5.25         6.65     (16.35)
-----------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations         $   4.56     $   3.78  $    (1.74)  $     5.74   $     7.17   $ (15.74)
-----------------------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
   Net investment income                                      (0.23)       (0.62)      (0.60)       (0.49)       (0.54)     (0.63)
   Net realized gain                                             --        (9.30)         --           --           --      (0.86)
   Tax return of capital                                         --           --          --           --        (0.01)        --
-----------------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                 $   4.33     $  (6.14) $    (2.34)  $     5.25   $     6.62   $ (17.23)
-----------------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                             $  36.94     $  32.61  $    38.75   $    41.09   $    35.84   $  29.22
===================================================================================================================================
Total return*                                                 13.99%       10.29%      (4.22)%      16.17%       24.86%    (34.07)%
Ratio of total expenses to average net assets+                 0.62%**      0.66%       0.72%        0.74%        0.71%      0.74%
Ratio of net investment income to average net assets+          1.37%**      1.54%       1.49%        1.37%        1.72%      1.62%
Portfolio turnover rate                                           8%**        41%         10%          10%          12%        11%
Net assets, end of period (in thousands)                   $377,389     $514,457  $1,860,141   $1,929,967   $1,279,182   $462,572
Ratios with reduction for fees paid indirectly:
   Total expenses                                              0.62%**      0.66%       0.72%        0.74%        0.71%      0.74%
   Net investment income                                       1.37%**      1.54%       1.49%        1.37%        1.72%      1.62%
===================================================================================================================================
</TABLE>

*    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.

+    Ratio with no reduction for fees paid indirectly.

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

                                   Pioneer Fund | Semiannual Report | 6/30/13 33
<PAGE>

Financial Highlights (continued)

<TABLE>
<CAPTION>
---------------------------------------------------------------------------------------------------------------------------
                                                             Six Months
                                                             Ended       Year      Year       Year      Year      Year
                                                             6/30/13     Ended     Ended      Ended     Ended     Ended
                                                             (unaudited) 12/31/12  12/31/11   12/31/10  12/31/09  12/31/08
---------------------------------------------------------------------------------------------------------------------------
<S>                                                          <C>         <C>       <C>        <C>       <C>       <C>
Class Z
Net asset value, beginning of period                         $32.53      $ 38.68   $ 41.03    $35.80    $29.20    $  46.41
---------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations:
   Net investment income                                     $ 0.20      $  0.55   $  0.50    $ 0.48    $ 0.48    $   0.63
   Net realized and unrealized gain (loss) on investments      4.30         3.15     (2.28)     5.23      6.64      (16.36)
---------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations           $ 4.50      $  3.70   $ (1.78)   $ 5.71    $ 7.12    $ (15.73)
---------------------------------------------------------------------------------------------------------------------------
Distributions to shareowners:
   Net investment income                                      (0.19)       (0.55)    (0.57)    (0.48)    (0.51)      (0.62)
   Net realized gain                                             --        (9.30)       --        --        --       (0.86)
   Tax return of capital                                         --           --        --        --     (0.01)         --
---------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                   $ 4.31      $ (6.15)  $ (2.35)   $ 5.23    $ 6.60    $ (17.21)
---------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period                               $36.84      $ 32.53   $ 38.68    $41.03    $35.80    $  29.20
===========================================================================================================================
Total return*                                                 13.84%       10.09%    (4.34)%   16.09%    24.72%     (34.06)%
Ratio of total expenses to average net assets+                 0.85%**      0.85%     0.85%     0.80%     0.85%       0.74%
Ratio of net investment income to average net assets+          1.11%**      1.40%     1.39%     1.31%     1.68%       1.57%
Portfolio turnover rate                                           8%**        41%       10%       10%       12%         11%
Net assets, end of period (in thousands)                     $1,084      $ 1,079   $ 1,042    $  580    $  310    $     58
Ratios with no waiver of fees and assumption of expenses by
   the Adviser and no reduction for fees paid indirectly:
   Total expenses                                              0.88%**      0.87%     0.99%     0.80%     1.03%       0.74%
   Net investment income                                       1.08%**      1.38%     1.25%     1.31%     1.50%       1.57%
Ratios with waiver of fees and assumption of expenses by
   the Adviser and reduction for fees paid indirectly:
   Net expenses                                                0.85%**      0.85%     0.85%     0.80%     0.85%       0.74%
   Net investment income                                       1.11%**      1.40%     1.39%     1.31%     1.68%       1.57%
===========================================================================================================================
</TABLE>

*    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.

+    Ratio with no reduction for fees paid indirectly.

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

34 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

Notes to Financial Statements | 6/30/13 (unaudited)

1. Organization and Significant Accounting Policies

Pioneer Fund (the Fund) is a Delaware statutory trust registered under the
Investment Company Act of 1940 as a diversified, open-end management investment
company. The investment objective of the Fund is to provide reasonable income
and capital growth.

The Fund offers six classes of shares designated as Class A, Class B, Class C,
Class R, Class Y and Class Z shares. Class Z shares were first publicly offered
on April 30, 2007. Effective as of the close of business on December 31, 2009,
Class B shares are no longer offered to new or existing shareholders, except
that dividends and/or capital gain distributions may continue to be reinvested
in Class B shares, and shareholders may exchange their Class B shares for Class
B shares of other Pioneer funds, as permitted by existing exchange privileges.
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 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 or
Class Z shares. Class B shares convert to Class A shares approximately eight
years after the date of purchase.

The Fund's financial statements have been prepared in conformity with U.S.
generally accepted accounting principles that require the management of the Fund
to, among other things, make estimates and assumptions that affect the reported
amounts of assets and liabilities, the disclosure of contingent assets and
liabilities at the date of the financial statements, and the reported amounts of
income, expenses and gains and losses on investments during the reporting
period. Actual results could differ from those estimates.

                                   Pioneer Fund | Semiannual Report | 6/30/13 35
<PAGE>

The following is a summary of significant accounting policies followed by the
Fund in the preparation of its financial statements, which are consistent with
those policies generally accepted in the investment company industry:

A.   Security Valuation

     Security transactions are recorded as of trade date. 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. In
     computing the net asset value, securities that have traded on an exchange
     are valued at the last sale price on the principal exchange where they are
     traded. Securities that have not traded on the date of valuation, or
     securities for which sale prices are not available, generally are valued at
     the mean between the last bid and asked prices. Short-term fixed income
     securities with remaining maturities of sixty days or less generally are
     valued at amortized cost. Shares of money market mutual funds are valued at
     their net asset value.

     Trading in foreign 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.

     Securities for which independent pricing services 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 or at the
     direction or with the approval of the Valuation Committee using fair value
     methods pursuant to procedures adopted by the Board of Trustees. The
     Valuation Committee is comprised of certain members of the Board of
     Trustees. 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. Pioneer Investment Management, Inc. (PIM) 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.

     At June 30, 2013 there were no securities that were valued using fair value
     methods (other than securities that were valued using prices supplied by
     independent pricing services). 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.

36 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

     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.

     Gains and losses on sales of investments are calculated on the identified
     cost method for both financial reporting and federal income tax purposes.

B.   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 market prices of those securities but are
     included with the net realized and unrealized gain or loss on investments.

C.   Forward Foreign Currency Contracts

     The Fund may enter into forward foreign currency contracts (contracts) for
     the purchase or sale of a specific foreign currency at a fixed price on a
     future date. All contracts are marked to market daily at the applicable
     exchange rates, and any resulting unrealized gains or losses are recorded
     in the Fund's financial statements. The Fund records realized gains and
     losses at the time a portfolio hedge is offset by entry into a closing
     transaction or extinguished by delivery of the currency. Risks may arise
     upon entering into these contracts from the potential inability of
     counterparties to meet the terms of the contract and from unanticipated
     movements in the value of foreign currencies relative to the U.S. dollar
     (see Note 8).

                                   Pioneer Fund | Semiannual Report | 6/30/13 37
<PAGE>

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 taxable income and net realized capital gains, if any, to its
     shareowners. Therefore, no provision for federal income taxes is required.
     As of June 30, 2013, the Fund did not have any interest and penalties
     related to uncertain tax positions, which, if applicable, would be recorded
     as an income tax expense in the Statement of Operations. Tax years for the
     prior three fiscal years are 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. generally accepted accounting principles.
     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 Fund's taxable year. The tax character of distributions
     paid during the years ended December 31, 2012 was as follows:

     <TABLE>
     <CAPTION>
     ---------------------------------------------------------------------------
                                                                           2012
     ---------------------------------------------------------------------------
     <S>                                                          <C>
     Distributions paid from:
     Ordinary income                                              $   75,565,986
     Long-term capital gain                                        1,061,714,271
     ---------------------------------------------------------------------------
          Total                                                   $1,137,280,257
     ===========================================================================
     </TABLE>

     The following shows the components of distributable earnings on a federal
     income tax basis at December 31, 2012:

     <TABLE>
     <CAPTION>
     ---------------------------------------------------------------------------
                                                                           2012
     ---------------------------------------------------------------------------
     <S>                                                         <C>
     Distributable earnings:
     Undistributed long-term gain                                $  106,932,690
     Capital loss carryforward                                        (593,388)
     Net unrealized gain                                          1,517,759,788
     ---------------------------------------------------------------------------
          Total                                                  $1,624,099,090
     ===========================================================================
     </TABLE>

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

38 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

E.   Fund Shares

     The Fund records sales and repurchases of its shares as of trade date.
     Pioneer Funds Distributor, Inc. (PFD), the principal underwriter for the
     Fund and a wholly owned indirect subsidiary of UniCredit S.p.A.
     (UniCredit), earned $270,288 in underwriting commissions on the sale of
     Class A shares during the six months ended June 30, 2013.

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. During the six months ended June 30, 2013, the Fund recognized
     gains of $2,719 in the settlement of class action lawsuits from several
     different companies, as reflected on the Statement of Operations.

     Distribution fees are calculated based on the average daily net asset value
     attributable to Class A, Class B, Class C, and Class R shares of the Fund,
     respectively (see Note 4). Class Y and Class Z shares do not pay
     distribution fees. All expenses and fees paid to the transfer agent,
     Pioneer Investment Management Shareholder Services, Inc. (PIMSS), 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 B, Class C, Class R, Class Y
     and Class Z shares can reflect different transfer agent and distribution
     expense rates.

G.   Risks

     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.

                                   Pioneer Fund | Semiannual Report | 6/30/13 39
<PAGE>

H.   Repurchase Agreements

     With respect to repurchase agreements entered into by the Fund, the value
     of the underlying securities (collateral), including accrued interest, is
     required to be equal to or in excess of the repurchase price. The
     collateral for all repurchase agreements is held in safekeeping in the
     customer-only account of the Fund's custodian or a subcustodian of the
     Fund. PIM is responsible for determining that the value of the collateral
     remains at least equal to the repurchase price.

2. Management Agreement PIM, a wholly owned indirect subsidiary of UniCredit,
manages the Fund's portfolio. Management fees are calculated daily at the annual
rate of 0.60% of the Fund's average daily net assets up to $7.5 billion, 0.575%
on the next $2.5 billion and 0.55% on assets over $10 billion. The basic fee can
increase or decrease by a maximum of 0.10% based on the investment performance
of the Fund's Class A shares as compared to the Standard and Poor's 500 Index.
The performance comparison is made for a rolling 36-month period. In addition,
Pioneer contractually limits any positive adjustment of the Fund's management
fee to 0.10% of the Fund's average daily net assets on an annual basis (i.e., to
a maximum annual fee of 0.70% after the performance adjustment). For the six
months ended June 30, 2013, the aggregate performance adjustment resulted in an
increase to the basic fee of $57,066. For the six months ended June 30, 2013,
the net management fee (excluding waivers and/or assumption of expenses) was
equivalent to 0.48% of the Fund's average daily net assets.

PIM has contractually agreed to limit ordinary operating expenses of the Fund to
the extent required to reduce Fund expenses to 0.85% of the average daily net
assets attributable to Class Z shares. The expense limitation for Class Z shares
is in effect through May 1, 2014. Fees waived and expenses reimbursed during the
six months ended June 30, 2013 are reflected on the Statement of Operations.
Class A, Class B, Class C, Class R and Class Y shares do not have an expense
limitation. There can be no assurance that PIM will extend the expense
limitation agreement for a class of shares beyond the date referred to above.

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
$2,291,240 in management fees, administrative costs and certain other
reimbursements payable to PIM at June 30, 2013.

40 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

3. Transfer Agent

PIMSS, a wholly owned indirect subsidiary of UniCredit, provides substantially
all transfer agent and shareowner services to the Fund at negotiated rates.

In addition, the Fund reimburses PIMSS for out-of-pocket expenses incurred by
PIMSS related to shareholder communications activities such as proxy and
statement mailings, outgoing phone calls and omnibus relationship contracts. For
the six months ended June 30, 2013, such out-of-pocket expenses by class of
shares were as follows:

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------
Shareholder Communications:
--------------------------------------------------------------------------------
<S>                                                                   <C>
Class A                                                               $  987,104
Class B                                                                   18,007
Class C                                                                   94,773
Class R                                                                   96,255
Class Y                                                                  231,791
Class Z                                                                    1,080
--------------------------------------------------------------------------------
  Total                                                               $1,429,010
================================================================================
</TABLE>


Included in "Due to affiliates" reflected on the Statement of Assets and
Liabilities is $619,444 in transfer agent fees and out-of-pocket reimbursements
payable to PIMSS at June 30, 2013.

4. Distribution and Service Plans

The Fund has adopted a Distribution Plan pursuant to Rule 12b-1 of the
Investment Company Act of 1940 with respect to its Class A, Class B, Class C and
Class R shares. Pursuant to the Plan, the Fund pays 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 PFD 1.00% of
the average daily net assets attributable to Class B and Class C shares. The fee
for Class B and 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 B and Class C
shares. Pursuant to the Plan, the Fund further pays PFD 0.50% of the average
daily net assets attributable to Class R shares for distribution services.
Included in "Due to affiliates" reflected on the Statement of Assets and
Liabilities is $1,173,186 in distribution fees payable to PFD at June 30, 2013.

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

                                   Pioneer Fund | Semiannual Report | 6/30/13 41
<PAGE>

services to retirement plans or plan participants holding shares of the Fund a
service fee of up to 0.25% of the Fund's average daily net assets attributable
to Class R shares held by such plans.

In addition, redemptions of each class of shares (except Class R, Class Y and
Class Z 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. Class B shares that are redeemed
within five years of purchase are subject to a CDSC at declining rates beginning
at 4.00%, based on the lower of cost or market value of shares being redeemed.
Redemptions of Class C shares within one year of purchase are subject to a CDSC
of 1.00%, based on the lower of cost or market value of shares being redeemed.
Shares purchased as part of an exchange remain subject to any CDSC that applied
to the original purchase of those shares. There is no CDSC for Class R, Class Y
or Class Z shares. Proceeds from the CDSCs are paid to PFD. For the six months
ended June 30, 2013, CDSCs in the amount of $15,607 were paid to PFD.

5. Expense Offset Arrangements

The Fund has entered into certain expense offset arrangements with PIMSS which
may result in a reduction in the Fund's total expenses due to interest earned on
cash held by PIMSS. For the six months ended June 30, 2013, the Fund's expenses
were not reduced under such arrangements.

6. Affiliated Companies

The Fund's investments in certain companies may exceed 5% of the outstanding
voting stock of those companies. Such companies are deemed affiliates of the
Fund for financial reporting purposes. The following summarizes transactions
with affiliates of the Fund for the six months ended June 30, 2013:

<TABLE>
<CAPTION>
-------------------------------------------------------------------------------------
                  Beginning                       Ending
                  Balance     Purchases  Sales    Balance    Dividend
Affiliates       (shares)    (shares)   (shares)  (shares)   Income      Value
-------------------------------------------------------------------------------------
<S>               <C>         <C>       <C>       <C>        <C>         <C>
John Wiley and
 Sons, Inc.       2,838,431   --        (54,181)  2,784,250  $1,381,927  $111,620,582
-------------------------------------------------------------------------------------
</TABLE>

7. 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 effect as of February 15, 2012 is in the amount of $215
million. Under such facility, depending on the type of loan, interest on
borrowings is

42 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

payable at the London Interbank Offered Rate (LIBOR) plus 0.90% on an annualized
basis, or the Alternate Base Rate, which is the greater of (a) the facility's
administrative agent's daily announced prime rate on the borrowing date, (b) 2%
plus the Federal Funds Rate on the borrowing date and (c) 2% plus the overnight
Euro dollar rate on the borrowing date. The Funds pay an annual commitment fee
to participate in the 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, 2013, the Fund had no borrowings
under the credit facility.

8. Forward Foreign Currency Contracts

At June 30, 2013, the Fund had entered into various forward foreign currency
contracts that obligate the Fund to deliver or take delivery of currencies at
specified future maturity dates. Alternatively, prior to the settlement date of
a forward foreign currency contract, the Fund may close out such contract by
entering into an offsetting contract. The average value of settlement hedge
contracts open during the six months ended June 30, 2013 was $66,032. At June
30, 2013, the Fund had no outstanding portfolio hedges. At June 30, 2013, the
Fund's gross forward currency settlement contracts receivable and payable were
$259,076 and $259,076, respectively, resulting in a net receivable of $0.

                                   Pioneer Fund | Semiannual Report | 6/30/13 43

<PAGE>

Trustees, Officers and Service Providers

Trustees                                  Officers
Thomas J. Perna, Chairman                 John F. Cogan, Jr., President*
David R. Bock                             Daniel K. Kingsbury, Executive
John F. Cogan, Jr.                            Vice President
Benjamin M. Friedman                      Mark E. Bradley, Treasurer**
Margaret B.W. Graham                      Christopher J. Kelley, Secretary
Daniel K. Kingsbury
Marguerite A. Piret
Stephen K. West

Investment Adviser and Administrator
Pioneer Investment Management, Inc.

Custodian and Sub-Administrator
Brown Brothers Harriman & Co.

Principal Underwriter
Pioneer Funds Distributor, Inc.

Legal Counsel
Bingham McCutchen LLP

Shareowner Services and Transfer Agent
Pioneer Investment Management Shareholder 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 us.pioneerinvestments.com. This information is also available on the
Securities and Exchange Commission's web site at www.sec.gov.

*  Chief Executive Officer of the Fund.

** Chief Financial and Accounting Officer of the Fund.

44 Pioneer Fund | Semiannual Report | 6/30/13
<PAGE>

How to Contact 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:
--------------------------------------------------------------------------------
PIMSS, Inc.
P.O. Box 55014
Boston, Massachusetts 02205-5014

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

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

Visit our web site: us.pioneerinvestments.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.
<PAGE>

[LOGO] PIONEER
       Investments(R)

Pioneer Investment Management, Inc.
60 State Street
Boston, MA 02109
us.pioneerinvestments.com

Securities offered through Pioneer Funds Distributor, Inc.
60 State Street, Boston, MA 02109
Underwriter of Pioneer Mutual Funds, Member SIPC
(C) 2013 Pioneer Investments 19404-07-0813
<PAGE>

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 10(a), 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.
<PAGE>
<TABLE>
<CAPTION>
                               SECTION II - POLICY

---------------- -------------------------------- -------------------------------------------------
SERVICE           SERVICE CATEGORY DESCRIPTION      SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES
CATEGORY
---------------- -------------------------------- -------------------------------------------------
<S>              <C>                              <C>
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.)
---------------- -------------------------------- -------------------------------------------------
<CAPTION>
 ------------------------------------- ------------------------------------
<S>                                    <C>
   AUDIT COMMITTEE APPROVAL POLICY               AUDIT COMMITTEE
                                                REPORTING POLICY
 ------------------------------------- ------------------------------------
<S>                                    <C>
 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"
 ------------------------------------- ------------------------------------
</TABLE>
<PAGE>
<TABLE>
<CAPTION>
                     SECTION III - POLICY DETAIL, CONTINUED

----------------------- --------------------------- -----------------------------------------------
   SERVICE CATEGORY          SERVICE CATEGORY        SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES
                               DESCRIPTION
----------------------- --------------------------- -----------------------------------------------
<S>                     <C>                         <C>
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"
------------------------------------- -------------------------
</TABLE>
<PAGE>
<TABLE>
<CAPTION>
                     SECTION III - POLICY DETAIL, CONTINUED

----------------------- --------------------------- -----------------------------------------------
   SERVICE CATEGORY          SERVICE CATEGORY        SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES
                               DESCRIPTION
----------------------- --------------------------- -----------------------------------------------
<S>                     <C>                         <C>
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.
----------------------- --------------------------- -----------------------------------------------
<CAPTION>
--------------------------------------- ------------------------
    AUDIT COMMITTEE APPROVAL POLICY         AUDIT COMMITTEE
                                            REPORTING POLICY
------------------------------------- --------------------------
<S>                                   <C>
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"
------------------------------------- --------------------------
</TABLE>
<PAGE>
<TABLE>
<CAPTION>
                     SECTION III - POLICY DETAIL, CONTINUED

----------------------- ------------------------- -----------------------------------------------
   SERVICE CATEGORY         SERVICE CATEGORY        SPECIFIC PROHIBITED SERVICE SUBCATEGORIES
                              DESCRIPTION
----------------------- ------------------------- -----------------------------------------------
<S>                     <C>                       <C>
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
----------------------- ------------------------- -----------------------------------------------
<CAPTION>
------------------------------------------- ------------------------------
     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.
------------------------------------------- ------------------------------
</TABLE>
--------------------------------------------------------------------------------
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 accountant's 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 registrant's accountant
for services rendered to the registrant, and rendered to the registrant's
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 registrant's audit committee of the board of trustees
has considered whether the provision of non-audit services that were rendered to
the registrant's 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 registrants 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 I Investments in securities of unaffiliated issuers
as of the close of the reporting period as set forth in 210.12-
12 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 registrants portfolio (Portfolio Manager). Also state each Portfolio
Managers 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 registrants equity securities
that is registered by the registrant pursuant to Section 12 of the
Exchange Act (15 U.S.C. 781). Instruction to paragraph (a). Disclose
all purchases covered by this Item, including purchases that do not
satisfy the conditions of the safe harbor of Rule 10b-18 under the
Exchange Act (17 CFR 240.10b-18), made in the period covered by the
report. Provide disclosures covering repurchases made on a monthly basis.
For example, if the reporting period began on January 16 and ended on
July 15, the chart would show repurchases for the months from January 16
through February 15, February 16 through March 15, March 16 through
April 15, April 16 through May 15, May 16 through June 15, and June 16
through July 15.

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 registrants board of directors, where
those changes were implemented after the registrant last provided
disclosure in response to the requirements of Item 7(d)(2)(ii)(G)
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 registrants board of
directors since the registrant last provided disclosure in response
to the requirements of Item 7(d)(2)(ii)(G) 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 officer or
officers and principal financial officer or officers, or persons performing
similar functions, about the effectiveness of the registrant's disclosure
controls and procedures (as defined in Rule 30a-2(c) under the Act (17 CFR
270.30a-2(c))) based on their evaluation of these controls and procedures as of
a date within 90 days of the filing date of the report that includes the
disclosure required by this paragraph.

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


(b) Disclose whether or not there were significant changes in the registrant's
internal controls or in other factors that could significantly affect these
controls subsequent to the date of their evaluation, including any corrective
actions with regard to significant deficiencies and material weaknesses.

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.

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

(a) 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.



(b) A separate certification for each principal executive officer and principal
financial officer of the registrant as required by Rule 30a-2 under the Act
(17 CFR 270.30a-2).

Filed herewith.


<PAGE>


                                   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 Fund


By (Signature and Title)* /s/ John F. Cogan, Jr.
John F. Cogan, Jr, President

Date August 29, 2013


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/ John F. Cogan, Jr.
John F. Cogan, Jr., President

Date August 29, 2013


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

Date August 29, 2013

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