15 USC 80a11 - Offers to exchange securities

(a) Approval by Commission for exchanges of securities on basis other than relative net asset value 
It shall be unlawful for any registered open-end company or any principal underwriter for such a company to make or cause to be made an offer to the holder of a security of such company or of any other open-end investment company to exchange his security for a security in the same or another such company on any basis other than the relative net asset values of the respective securities to be exchanged, unless the terms of the offer have first been submitted to and approved by the Commission or are in accordance with such rules and regulations as the Commission may have prescribed in respect of such offers which are in effect at the time such offer is made. For the purposes of this section, (A) an offer by a principal underwriter means an offer communicated to holders of securities of a class or series but does not include an offer made by such principal underwriter to an individual investor in the course of a retail business conducted by such principal underwriter, and (B) the net asset value means the net asset value which is in effect for the purpose of determining the price at which the securities, or class or series of securities involved, are offered for sale to the public either (1) at the time of the receipt by the offeror of the acceptance of the offer or (2) at such later times as is specified in the offer.
(b) Application of section to offers pursuant to plan of reorganization 
The provisions of this section shall not apply to any offer made pursuant to any plan of reorganization, which is submitted to and requires the approval of the holders of at least a majority of the outstanding shares of the class or series to which the security owned by the offeree belongs.
(c) Application of section to specific exchange offers 
The provisions of subsection (a) of this section shall be applicable, irrespective of the basis of exchange,
(1)  to any offer of exchange of any security of a registered open-end company for a security of a registered unit investment trust or registered face-amount certificate company; and

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(2)  to any type of offer of exchange of the securities of registered unit investment trusts or registered face-amount certificate companies for the securities of any other investment company.