Margin Operations

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 — day-trade buying power = (equity - $25,000 minimum) × 4. 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:

• FINRA Rule 4210 minimum: 25% equity for long positions. Account equity = market value of securities minus debit balance. If equity falls below 25% of market value, a maintenance margin call is triggered.
• House maintenance requirements: Most broker-dealers impose requirements above the FINRA minimum, typically 30-40% for diversified accounts. House requirements vary by firm and may change based on market conditions.
• Concentrated position margin: Single-stock positions exceeding a threshold (e.g., 40-60% of account value) face elevated margin requirements, often 50-75% or higher. This discourages excessive concentration in margin accounts.
• Long margin formula: Maintenance call triggered when equity / market value < maintenance requirement, where account equity = market value - debit balance. Equivalently, a call is triggered when market value falls to: debit balance / (1 - maintenance requirement). The call amount due is (maintenance requirement × market value) - equity.
• Short margin requirements: Short positions require initial margin of 50% (Reg T) and maintenance of 30% of market value (FINRA minimum). Short account equity = credit balance - market value of short securities. A short squeeze (rising prices) increases the maintenance requirement.
• Options margin: Options strategies have specific margin requirements under FINRA Rule 4210 and exchange rules. Covered calls require no additional margin (shares serve as collateral). Naked short options require substantial margin — typically the greater of: (a) option premium + 20% of underlying value - out-of-the-money amount, or (b) option premium + 10% of underlying value. Spreads have defined-risk margin equal to the maximum loss.

Portfolio Margin

A risk-based margining methodology that can significantly reduce margin requirements for hedged or diversified portfolios:

• Methodology: Uses the Options Clearing Corporation's Theoretical Intermarket Margin System (OCC TIMS) to compute margin based on the theoretical maximum loss of the portfolio under a range of stress scenarios, rather than applying fixed percentage requirements to each position independently.
• Eligibility requirements: Minimum account equity of $100,000 (FINRA Rule 4210(g)), options trading approval (typically Level 3 or 4), and the firm may impose additional requirements such as minimum net worth, trading experience, or completion of a portfolio margin agreement.
• Stress test scenarios: The OCC TIMS model evaluates portfolio profit and loss under standardized moves:
• Large-cap equities: +/- 15% (with intermediate points at +/- 5%, +/- 10%)
• Small-cap equities: +/- 10% higher stress (effectively +/- 25%)
• Broad market indices: +/- 8% to +/- 15%
• High-volatility securities: firm-specific add-ons
• The largest theoretical loss across all scenarios becomes the margin requirement
• Portfolio margin vs Reg T comparison: A hedged equity portfolio with offsetting options positions might require 50% margin under Reg T (applied position-by-position) but only 10-20% under portfolio margin (reflecting the actual net risk). Conversely, a concentrated, unhedged portfolio may see little benefit from portfolio margin.
• Benefits: More efficient use of capital, margin requirements that reflect actual portfolio risk, ability to maintain larger or more complex positions, and alignment between margin and true economic risk.
• Risks: Lower margin requirements increase leverage, amplifying both gains and losses. A sudden correlation shift or gap move can produce losses exceeding the stress test scenarios. Portfolio margin accounts can experience rapid, severe margin calls during market dislocations.

Margin Call Types

Multiple types of margin calls can arise, each with distinct triggers, deadlines, and resolution procedures:

• Reg T initial call (federal call): Triggered when a client purchases marginable securities and the account does not have sufficient equity to satisfy the 50% Reg T requirement. Must be met by settlement date (T+1 for most securities). Met by depositing cash or fully paid marginable securities. Failure to meet triggers liquidation and potential 90-day account restriction.
• Maintenance margin call (house call): Triggered when account equity falls below the firm's house maintenance requirement (typically 30-40%). The client is typically given T+5 business days (or less, at the firm's discretion) to deposit funds or securities, or the firm will liquidate positions. Unlike Reg T calls, there is no SRO extension mechanism for house calls — the timeline is at the firm's discretion.
• Exchange minimum call: Triggered when account equity falls below the FINRA/exchange minimum of 25%. These calls demand immediate attention and may be subject to same-day or next-day resolution.
• Day-trade call: Triggered when a pattern day trader's account equity falls below the $25,000 minimum or when day-trade buying power is exceeded. Must be met within 5 business days. Failure restricts the account to cash-available trading.
• Concentration call: Triggered when a single position exceeds the firm's concentration threshold and the account's equity is insufficient to meet the elevated requirement. Common in accounts holding large positions in a single stock.

Margin Call Procedures

The end-to-end process from call generation through resolution:

• Call generation: Margin calls are generated during the end-of-day mark-to-market process. The firm's margin system reprices all positions at closing market values, recalculates equity and margin requirements, and identifies accounts in deficit. Intraday monitoring may generate real-time alerts for large deficits.