If X stock is selling at $100 per share, the customer would pay about $3,250 for a contract to purchase 100 shares of X at $70 per share within a 30-day period. The contract would be guaranteed by an exchange member, as are standard "puts" and "calls". When the contract is made with the customer, the seller, who will also be the writer of the contract, will immediately purchase 100 shares of X at $100 per share through the guarantor member firm in a margin account. If the customer exercises the option, the shares will be delivered to him; if the option is not exercised, the writer will sell the shares in the margin account to close out the transaction. As a practical matter, it is anticipated that the customer will exercise the option in almost every case.
12 C.F.R. §220.122