17 CFR 301.300a: a Form 300-A, for summary of buy-ins or sell-outs of all open contractual commitments.

This form shall be filed as required by § 300.303 of this chapter with the trustee in a proceeding under section 5 of the Act by a broker-dealer who executed transactions out of which arose open contractual commitments, as defined by § 300.300(c) of this chapter, with the debtor in the proceeding. The form shall be used to summarize the buy-ins and sell-outs of those open contractual commitments and shall be accompanied by the forms described in §§ 301.300b and 301.300c.