Margin Requirements Reference Table
Direct answer: Margin requirements determine how much you can borrow to buy securities. Initial margin (Regulation T) requires at least 50% equity for stock purchases. Maintenance margin (typically 25% minimum per FINRA, or 30-40% per broker) triggers margin calls if equity falls below the threshold. Options margin requirements vary by strategy and broker.
Standard Margin Requirements by Security Type
| Requirement Type | Stocks (Long) | Stocks (Short) | ETFs | Options |
|---|---|---|---|---|
| Initial margin (Reg T) | 50% | 150% (50% + 100% proceeds held) | 50% | Strategy dependent |
| Minimum maintenance margin (FINRA) | 25% | 30% | 25% | N/A (options have own rules) |
| Typical broker maintenance | 30-40% | 30-40% | 30-40% | Varies by strategy |
| Day trading initial margin (PDT accounts) | 25% | 25% | 25% | N/A |
| Concentrated position (>60% of account in one stock) | Often 40-100% | Higher than standard | Often 40-100% | N/A |
Source: Federal Reserve: Regulation T. Last verified: September 2026.
Frequently asked questions
How is a margin call calculated?
A margin call is triggered when your account equity falls below the maintenance margin requirement. Example: You buy $10,000 of stock on 50% margin (you own $5,000 equity, broker loans $5,000). Stock falls to $7,000. Equity = $7,000 - $5,000 loan = $2,000. Maintenance margin at 25% of $7,000 = $1,750. No margin call yet. Stock falls to $6,600. Equity = $1,600. Maintenance = $1,650. Margin call: you need $50 more equity. To meet the call: deposit cash, deposit securities, or sell securities. Brokers can liquidate your positions immediately and without notice to meet a margin call -- you have no right to choose what is sold.
What is portfolio margin and who qualifies?
Portfolio margin (Risk-Based Haircuts, or RBH) is an advanced margining system available to sophisticated investors with at least $150,000 in a margin account. Instead of Reg T's flat 50% initial margin, portfolio margin calculates requirements based on the net risk of the entire portfolio using stress scenarios. Highly diversified portfolios may have lower margin requirements than Reg T; concentrated or leveraged positions may have higher. Benefits: higher leverage for well-hedged portfolios; more flexibility for options strategies. Risks: complex calculations may obscure true leverage; portfolio margin requirements can increase rapidly during volatile markets, generating unexpected margin calls.
What is margin interest and how is it calculated?
Margin interest is charged daily on the outstanding loan balance. Rates vary by broker and loan balance size (larger balances typically get lower rates). Example rates (approximate 2024): Interactive Brokers IBKR Pro: 5.83% for under $100K (benchmarked to fed funds + spread). Fidelity: 8.325% base rate for under $25K. Charles Schwab: 8.575% for under $25K. Calculation: Daily interest = (Loan balance x annual rate) / 360. On a $10,000 loan at 8%: ($10,000 x 8%) / 360 = $2.22 per day. Monthly: approximately $66. Margin interest is typically tax-deductible against net investment income (Form 4952), subject to limitations.