It shall constitute a “fraudulent, deceptive, or manipulative act or practice” as used in section 15(c)(2) of the Act, for any broker, dealer or municipal securities dealer participating in any distribution of securities, other than a firm-commitment underwriting, to accept any part of the sale price of any security being distributed unless:

(a) The money or other consideration received is promptly transmitted to the persons entitled thereto; or

(b) If the distribution is being made on an “all-or-none” basis, or on any other basis which contemplates that payment is not to be made to the person on whose behalf the distribution is being made until some further event or contingency occurs, (1) the money or other consideration received is promptly deposited in a separate bank account, as agent or trustee for the persons who have the beneficial interests therein, until the appropriate event or contingency has occurred, and then the funds are promptly transmitted or returned to the persons entitled thereto, or (2) all such funds are promptly transmitted to a bank which has agreed in writing to hold all such funds in escrow for the persons who have the beneficial interests therein and to transmit or return such funds directly to the persons entitled thereto when the appropriate event or contingency has occurred.