Margin Operations

Core Concepts

Regulation T Initial Margin

The Federal Reserve's Regulation T establishes the initial margin requirement for purchasing securities on credit. Key provisions:

• 50% initial margin requirement: An investor must deposit at least 50% of the purchase price of marginable securities. For a $100,000 purchase, the investor must deposit $50,000 (cash or marginable securities); the broker-dealer may lend the remaining $50,000.
• Reg T buying power: The maximum dollar amount a client can purchase given their available equity. Buying power = SMA x 2 (for equity securities under Reg T). If a client deposits $100,000 cash in a new margin account, buying power is $200,000.
• Special Memorandum Account (SMA): A bookkeeping entry that tracks the client's excess Reg T equity. SMA increases when: the account has excess equity above 50%, securities are sold, dividends or cash are deposited. SMA decreases when used to purchase securities or withdraw cash. SMA is a high-water mark — it does not decrease when market values decline (unless used).
• Reg T extension procedures: When a client fails to meet the initial margin requirement by settlement date, the broker-dealer must request an extension from a self-regulatory organization (SRO). Extensions are typically granted for 1-5 business days. Failure to meet the call results in forced liquidation and a 90-day freeze (restricted account).
• Exempt securities: U.S. government bonds, municipal bonds, and certain agency securities are exempt from Reg T margin requirements — they can be purchased with lower or no initial margin.
• Day-trade margin: FINRA Rule 4210 provides pattern day traders (4+ day trades in 5 business days) with 4:1 intraday buying power (25% margin) but requires a minimum equity of $25,000. Overnight positions revert to standard 2:1 Reg T buying power.

Maintenance Margin

After the initial purchase, ongoing maintenance margin requirements determine the minimum equity the account must maintain: