PIONEER FUNDAMENTAL GROWTH FUND

                     (a series of Pioneer Series Trust X)

                  Multiple Class Plan Pursuant to Rule 18f-3
    Class A Shares, Class C Shares, Class K Shares, Class R Shares, Class T
                           Shares and Class Y Shares

                               January 10, 2017

   Each class of shares of Pioneer Fundamental Growth Fund (the "Fund") will
have the same relative rights and privileges and be subject to the same sales
charges, fees and expenses, except as set forth below. The Board of Trustees
may determine in the future that other distribution arrangements, allocations
of expenses (whether ordinary or extraordinary) or services to be provided to a
class of shares are appropriate and amend this Multiple Class Plan accordingly
without the approval of shareholders of any class. Except as set forth in the
Fund's prospectus(es), shares may be exchanged only for shares of the same
class of another Pioneer mutual fund.

   Article I. Class A Shares

   Class A Shares are sold at net asset value per share and subject to the
initial sales charge schedule or contingent deferred sales charge ("CDSC") and
minimum purchase requirements as set forth in the Fund's prospectus. Class A
Shares shall be entitled to the shareholder services set forth from time to
time in the Fund's prospectus with respect to Class A Shares. Class A Shares
are subject to fees calculated as a stated percentage of the net assets
attributable to Class A Shares under the Fund's Class A Rule 12b-1 Distribution
Plan as set forth in such Distribution Plan. The Class A Shareholders have
exclusive voting rights, if any, with respect to the Fund's Class A Rule 12b-1
Distribution Plan. Transfer agency fees are allocated to Class A Shares on a
per account basis except to the extent, if any, such an allocation would cause
the Fund to fail to satisfy any requirement necessary to obtain or rely on a
private letter ruling from the Internal Revenue Service ("IRS") relating to the
issuance of multiple classes of shares. Class A Shares shall bear the costs and
expenses associated with conducting a shareholder meeting for matters relating
to Class A Shares.

   The initial purchase date for Class A Shares acquired through
(i) reinvestment of dividends on Class A Shares or (ii) exchange from another
Pioneer mutual fund will be deemed to be the date on which the original Class A
Shares were purchased.

   Article II. Class C Shares

   Class C Shares are sold at net asset value per share without the imposition
of an initial sales charge. Class C Shares redeemed within one (1) year of
purchase will be subject to a CDSC as set forth in the Fund's prospectus.
Class C Shares are sold subject to the minimum purchase requirements set forth
in the Fund's prospectus. Class C Shares shall be entitled to the shareholder
services set forth from time to time in the Fund's prospectus with respect to
Class C Shares. Class C Shares are subject to fees calculated as a stated
percentage of the net assets



attributable to Class C Shares under the Class C Rule 12b-1 Distribution Plan
as set forth in such Distribution Plan. The Class C Shareholders of the Fund
have exclusive voting rights, if any, with respect to the Fund's Class C Rule
12b-1 Distribution Plan. Transfer agency fees are allocated to Class C Shares
on a per account basis except to the extent, if any, such an allocation would
cause the Fund to fail to satisfy any requirement necessary to obtain or rely
on a private letter ruling from the IRS relating to the issuance of multiple
classes of shares. Class C Shares shall bear the costs and expenses associated
with conducting a shareholder meeting for matters relating to Class C Shares.

   The initial purchase date for Class C Shares acquired through
(i) reinvestment of dividends on Class C Shares or (ii) exchange from another
Pioneer mutual fund will be deemed to be the date on which the original Class C
Shares were purchased.

   Article III. Class K Shares

   Class K Shares are sold at net asset value per share without the imposition
of an initial sales charge. Class K Shares are not subject to a CDSC upon
redemption regardless of the length of the period of time such shares are held.
Class K Shares are sold subject to the minimum purchase requirements set forth
in the Fund's prospectus. Class K Shares shall be entitled to the shareholder
services set forth from time to time in the Fund's prospectus with respect to
Class K Shares.

   Class K Shares are not subject to fees payable under a distribution or other
plan adopted pursuant to Rule 12b-1 under the Investment Company Act of 1940,
as amended (the "Act"). The Class K Shareholders of the Fund have exclusive
voting rights, if any, with respect to the Fund's possible future adoption of a
Class K Rule 12b-1 Distribution Plan. Transfer agency fees are allocated to
Class K Shares on a per account basis except to the extent, if any, such an
allocation would cause the Fund to fail to satisfy any requirement necessary to
obtain or rely on a private letter ruling from the IRS relating to the issuance
of multiple classes of shares. Class K Shares shall bear the costs and expenses
associated with conducting a shareholder meeting for matters relating to
Class K Shares.

   The initial purchase date for Class K Shares acquired through
(i) reinvestment of dividends on Class K Shares or (ii) exchange from another
Pioneer mutual fund will be deemed to be the date on which the original Class K
Shares were purchased.

   Article IV. Class R Shares

   Class R Shares are sold at net asset value per share without an initial
sales charge. Class R Shares are not subject to a CSDC upon redemption
regardless of the length of period of time such Shares are held. Class R Shares
are sold to retirement plans that meet the eligibility requirements for Class R
Shares set forth in the Fund's prospectus. Class R Shares shall be entitled to
the shareholder services set forth from time to time in the Fund's prospectus
with respect to Class R Shares. Class R Shares are subject to fees calculated
as a stated percentage of the net assets attributable to Class R Shares under
the Class R Rule 12b-1 Distribution Plan as set forth in such Distribution
Plan. The Class R Shareholders of the Fund have exclusive voting rights, if
any, with respect to the Fund's Class R Rule 12b-1 Distribution Plan. Transfer
agency

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fees are allocated to Class R Shares on a per account basis except to the
extent, if any, such an allocation would cause the Fund to fail to satisfy any
requirement necessary to obtain or rely on a private letter ruling from the IRS
relating to the issuance of multiple classes of shares. Class R Shares shall
bear the costs and expenses associated with conducting a shareholder meeting
for matters relating to Class R Shares.

   The initial purchase date for Class R Shares acquired through
(i) reinvestment of dividends on Class R Shares or (ii) exchange from another
Pioneer mutual fund will be deemed to be the date on which the original Class R
Shares were purchased.

   Article V. Class T Shares

   Class T Shares are sold at net asset value per share and subject to the
initial sales charge schedule and minimum purchase requirements as set forth in
the Fund's prospectus. Class T Shares are not subject to a CDSC upon redemption
regardless of the length of the period of time such shares are held. Class T
Shares shall be entitled to the shareholder services set forth from time to
time in the Fund's prospectus with respect to Class T Shares. Class T Shares
are subject to fees calculated as a stated percentage of the net assets
attributable to Class T Shares under the Fund's Class T Rule 12b-1 Distribution
Plan as set forth in such Distribution Plan. The Class T Shareholders have
exclusive voting rights, if any, with respect to the Fund's Class T Rule 12b-1
Distribution Plan. Transfer agency fees are allocated to Class T Shares on a
per account basis except to the extent, if any, such an allocation would cause
the Fund to fail to satisfy any requirement necessary to obtain or rely on a
private letter ruling from the Internal Revenue Service ("IRS") relating to the
issuance of multiple classes of shares. Class T Shares shall bear the costs and
expenses associated with conducting a shareholder meeting for matters relating
to Class T Shares.

   The initial purchase date for Class T Shares acquired through reinvestment
of dividends on Class T Shares will be deemed to be the date on which the
original Class T Shares were purchased.

   There is no exchange privilege for Class T Shares. Rights of accumulation
and letters of intent are not applicable to Class T Shares.

   Article VI. Class Y Shares

   Class Y Shares are sold at net asset value per share without the imposition
of an initial sales charge. Class Y Shares are not subject to a CDSC upon
redemption regardless of the length of the period of time such shares are held.
Class Y Shares are sold subject to the minimum purchase requirements set forth
in the Fund's prospectus. Class Y Shares shall be entitled to the shareholder
services set forth from time to time in the Fund's prospectus with respect to
Class Y Shares.

   Class Y Shares are not subject to fees payable under a distribution or other
plan adopted pursuant to Rule 12b-1 under the Act. The Class Y Shareholders of
the Fund have exclusive voting rights, if any, with respect to the Fund's
possible future adoption of a Class Y Rule 12b-1 Distribution Plan. Transfer
agency fees are allocated to Class Y Shares on a per account basis except to
the extent, if any, such an allocation would cause the Fund to fail to satisfy
any

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requirement necessary to obtain or rely on a private letter ruling from the IRS
relating to the issuance of multiple classes of shares. Class Y Shares shall
bear the costs and expenses associated with conducting a shareholder meeting
for matters relating to Class Y Shares.

   The initial purchase date for Class Y Shares acquired through
(i) reinvestment of dividends on Class Y Shares or (ii) exchange from another
Pioneer mutual fund will be deemed to be the date on which the original Class Y
Shares were purchased.

   Article VII. Approval by Board of Trustees

   This Multiple Class Plan shall not take effect until it has been approved by
the vote of a majority (or whatever greater percentage may, from time to time,
be required under Rule 18f-3 under the Act) of (a) all of the Trustees of the
Fund and (b) those of the Trustees who are not "interested persons" (as such
term may be from time to time defined under the Act) of the Fund.

   Article VIII. Amendments

   No material amendment to this Multiple Class Plan shall be effective unless
it is approved by the Board of Trustees of the Fund in the same manner as is
provided for approval of this Multiple Class Plan in Article VII.

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