In the stock market, buying on margin means borrowing from a brokerage firm against account collateral. For a new purchase of margin-eligible U.S. stock, Regulation T generally permits borrowing up to 50% of the purchase price; brokers may require more equity. Short stock has separate borrowing and collateral requirements. Interest, price changes and higher house requirements can cause additional funding needs or liquidation.
Margin Requirements for Option Writers
In options trading however, "margin" also refers to the cash or securities required to be deposited by an option writer with his brokerage firm as collateral for the writer's obligation. See margin requirements.
Long-dated options
Under FINRA’s strategy-based rules, qualifying listed long equity and equity-index puts and calls with more than nine months remaining can have a 75% margin requirement. This is the equity/collateral requirement, not permission to borrow 75% of the premium. Shorter-dated long options generally must be paid for in full, and broker eligibility, house rules and portfolio-margin treatment can differ. Check the requirement as the option ages.
U.S. intraday margin transition in 2026
FINRA’s new intraday margin framework took effect on June 4, 2026, with firms permitted to transition through October 20, 2027. A firm still using the old framework can retain its pattern-day-trader restrictions, including the $25,000 equity requirement. A firm that has transitioned uses position-based intraday requirements without that trade-count designation or $25,000 minimum. House requirements can be higher. Confirm which framework your broker applies; the transition also matters to intraday options activity. See FINRA’s explanation.
