17 CFR § 300.502 - Claim for securities.

(a) Where the Debtor held cash in an account for a customer, the customer has a “claim for securities” with respect to any authorized securities purchase:

(1) If the Debtor has sent written confirmation to the customer that the securities in question have been purchased for or sold to the customer's account; or

(2) Whether or not such a written confirmation has been sent, if the securities in question have become the subject of completed or executory contract for sale for or purchase from the account.

(b) Where the Debtor held securities in an account for a customer, the customer has a “claim for securities”, notwithstanding the fact that the customer has ordered the securities sold for the account, unless:

(1) The Debtor has sent written confirmation to the customer that the securities in question have been sold for or purchased from the customer's account; or

(2) Whether or not written confirmation of the purchase has been sent, if the securities in question have become the subject of completed or executory contract for sale for or purchase form the account.