In case a customer purchases a security (other than an exempted security) in the special cash account and does not make full cash payment for the security within 7 days after the date on which the security is so purchased, the creditor shall, except as provided in subparagraphs (3)-(7) of this paragraph, promptly cancel or otherwise liquidate the transaction or the unsettled portion thereof.
Section 220.4(c)(3) , one of the exceptions referred to, provides in relevant part as follows:
If the security when so purchased is an unissued security, the period applicable to the transaction under subparagraph (2) of this paragraph shall be 7 days after the date on which the security is made available by the issuer for delivery to purchasers.
12 C.F.R. §220.118