Exhibit (12)


                  [FORM OF OPINION OF BINGHAM McCUTCHEN LLP]

________ __, 2009


Regions Morgan Keegan Select Funds
50 North Front Street
Memphis, Tennessee 38103


Pioneer Fund
60 State Street
Boston, Massachusetts 02109


Ladies and Gentlemen:

This opinion is furnished to you pursuant to paragraph 8.5 of the Agreement and
Plan of Reorganization, dated as of   , 2009 (the "Agreement"), by and between
Pioneer Fund (the "Acquiring Trust"), a Delaware statutory trust, on behalf of
Pioneer Fund, the sole series thereof (the "Acquiring Fund"), and Regions
Morgan Keegan Select Funds (the "Acquired Trust"), a Massachusetts business
trust, on behalf of Regions Morgan Keegan Select Core Equity Fund, a series
thereof (the "Acquired Fund"). All capitalized terms not otherwise defined
herein have the meanings ascribed to them in the Agreement. The Agreement
contemplates the acquisition of all of the assets of the Acquired Fund by the
Acquiring Fund in exchange for (a) the assumption by the Acquiring Fund of the
stated liabilities of the Acquired Fund and (b) the issuance and delivery by
the Acquiring Fund to the Acquired Fund, for distribution, in accordance with
Section 1.4 of the Agreement, pro rata within each class of Acquired Fund
Shares, to the Acquired Fund Shareholders in exchange for their Acquired Fund
Shares and in complete liquidation of the Acquired Fund, of a number of
Acquiring Fund Shares of the corresponding class having an aggregate net asset
value equal to the value of such assets, less the amount of such liabilities,
of the Acquired Fund so transferred to the Acquiring Fund (the "Transaction").

In connection with this opinion we have examined and relied upon the originals
or copies, certified or otherwise identified to us to our satisfaction, of the
Agreement, the Combined Proxy Statement and Prospectus on Form N-14 filed with
the Securities and Exchange Commission on or about February 12, 2009 with
respect to the Transaction, and related documents (collectively, the
"Transaction Documents"). In that examination, we have assumed the genuineness
of all signatures, the authenticity and completeness of all documents
purporting to be originals (whether reviewed by us in original or copy form)
and the conformity to the originals of all documents purporting to be copies.

As to certain factual matters, we have relied with your consent upon, and our
opinion is limited by, the representations of the various parties set forth in
the Transaction Documents, and in certificates of the Acquired Trust and the
Acquiring Trust dated as of the date hereof and attached hereto (the
"Certificates"). Our opinion assumes (i) that all representations set forth in
the Transaction Documents and in the Certificates will be true and correct in
all material respects as of the date of the Transaction, and (ii) that the
Agreement is implemented in accordance with its terms and consistent with the
representations set forth in the Transaction Documents and Certificates. Our
opinion is limited solely to the provisions of the Internal Revenue Code as
presently in effect (the "Code") and the regulations, rulings, and
interpretations thereof in force as of this date. We assume no obligation to
update our opinion to reflect any changes in law or in the interpretation
thereof that may hereafter occur.

On the basis of and subject to the foregoing, we are of the opinion that, for
United States federal income tax purposes:

  1. The Reorganization will constitute a "reorganization" within the meaning
     of Section 368(a) of the Code, and the Acquiring Fund and the Acquired
     Fund will each be a "party to a reorganization" within the meaning of
     Section 368(b) of the Code.

  2. No gain or loss will be recognized by the Acquired Fund upon the transfer
     of the Acquired Assets to the Acquiring Fund solely in exchange for
     Acquiring Fund Shares and the assumption by the Acquiring Fund of all of
     the Assumed Liabilities, or upon the distribution of the Acquiring Fund
     Shares by the Acquired Fund to its shareholders in liquidation, except for
     (A) any gain or loss that may be recognized on the transfer of "section
     1256 contracts" as defined in Section 1256(b) of the Code, (B) any gain
     that may be recognized on the transfer of stock in a "passive foreign
     investment company" as defined in Section 1297(a) of the Code and (C) any
     other gain that may be required to be recognized as a result of the
     closing of the Acquired Fund's tax year.

  3. The tax basis in the hands of the Acquiring Fund of each Acquired Asset
     so transferred will be the same as the tax basis of such Acquired Asset in
     the hands of the Acquired Fund immediately prior to the transfer,
     increased by the amount of gain (or decreased by the amount of loss), if
     any, recognized by the Acquired Fund upon the transfer.


  4. The holding period of each Acquired Asset in the hands of the Acquiring
     Fund, other than assets, if any, with respect to which gain or loss is
     required to be recognized, will include in each instance the period during
     which the Acquired Asset was held by the Acquired Fund (except where
     investment activities of the Acquiring Fund have the effect of reducing or
     eliminating the holding period with respect to an asset).

  5. No gain or loss will be recognized by the Acquiring Fund upon receipt of
     the Acquired Assets solely in exchange for Acquiring Fund Shares and the
     assumption by the Acquiring Fund of the Assumed Liabilities.

  6. No gain or loss will be recognized by the Acquired Fund Shareholders upon
     the exchange of all of their Acquired Fund Shares solely for Acquiring
     Fund Shares as part of the Reorganization.

  7. The aggregate basis of the Acquiring Fund Shares that an Acquired Fund
     Shareholder receives in the Reorganization will be the same as the
     aggregate basis of the Acquired Fund Shares exchanged therefor.

  8. The holding period for the Acquiring Fund Shares received by each
     Acquired Fund Shareholder will include the holding period of the Acquired
     Fund Shares exchanged therefor, provided that such Acquired Fund Shares
     were held as capital assets on the date of the exchange.

This opinion is being delivered solely to you for your use in connection with
the referenced transaction, and may not be relied upon by any other person or
used for any other purpose.

Very truly yours,



BINGHAM MCCUTCHEN LLP