12 CFR 220.5: Special memorandum account.

(a) A special memorandum account (SMA) may be maintained in conjunction with a margin account. A single entry amount may be used to represent both a credit to the SMA and a debit to the margin account. A transfer between the two accounts may be effected by an increase or reduction in the entry. When computing the equity in a margin account, the single entry amount shall be considered as a debit in the margin account. A payment to the customer or on the customer's behalf or a transfer to any of the customer's other accounts from the SMA reduces the single entry amount.

(b) The SMA may contain the following entries:

(1) Dividend and interest payments;

(2) Cash not required by this part, including cash deposited to meet a maintenance margin call or to meet any requirement of a self-regulatory organization that is not imposed by this part;

(3) Proceeds of a sale of securities or cash no longer required on any expired or liquidated security position that may be withdrawn under § 220.4(e); and

(4) Margin excess transferred from the margin account under § 220.4(e)(2).