Margin trading is the practice of using borrowed funds from a broker to increase the size of a trading position beyond what would be possible with cash alone. The trader puts down a fraction of the total trade value, known as the initial margin, and the broker lends the rest. The assets in the account serve as collateral. This creates leverage, which amplifies both gains and losses relative to the capital deposited. A trader who buys $10,000 worth of stock with $5,000 of their own money and $5,000 borrowed is using 2:1 leverage. If the stock rises 10%, the position is worth $11,000. After repaying the $5,000 loan, the trader's equity is $6,000, a 20% return on the original $5,000. If the stock falls 10%, the position is worth $9,000, equity drops to $4,000, and the loss is 20%. The broker charges interest on the borrowed amount, and the trader remains liable for the full loan regardless of performance.
A cash account requires the trader to pay for securities in full with settled funds. Buying $5,000 of stock requires $5,000 in the account. A margin account allows the trader to borrow against the value of eligible securities already held. This unlocks three capabilities not available in a cash account: buying additional shares with borrowed money, short selling, and trading certain derivatives that require a margin deposit. To open a margin account, a broker typically requires a minimum deposit, often $2,000 in the United States under Regulation T, though some brokers set higher minimums. The securities in the account must be marginable; penny stocks, some small-cap shares, and certain ETFs may not qualify.
Initial margin is the percentage of the purchase price the trader must deposit in cash or eligible securities. Under Regulation T, the initial margin for stocks is 50%, meaning a trader can borrow up to 50% of the purchase price. Some brokers offer portfolio margin or risk-based margin for experienced traders, which can reduce the initial requirement based on the overall risk of the portfolio.
Maintenance margin is the minimum equity percentage the trader must maintain in the account after the purchase. FINRA requires at least 25% for long stock positions, but many brokers set higher house requirements, often 30% to 40%. For short positions, the maintenance requirement is typically higher, often 30% of the market value.
Equity is the current value of the account minus the borrowed amount. If a trader buys $10,000 of stock with $5,000 borrowed, equity starts at $5,000. If the stock value falls to $8,000, equity drops to $3,000.
A margin call occurs when equity falls below the maintenance margin requirement. The broker demands that the trader deposit additional cash or securities, or liquidate positions, to restore equity to the required level. If the trader does not act, the broker can sell assets without prior notice.
A trader opens a margin account with $10,000 in cash. They want to buy shares of a company trading at $50 per share. With 50% initial margin, they can buy up to $20,000 worth of stock, or 400 shares, borrowing $10,000 from the broker. The account holds 400 shares worth $20,000, with a $10,000 loan balance and $10,000 equity.
Assume the broker's maintenance margin is 30%. The maintenance requirement is 30% of the current market value of the position. The minimum equity required is 0.30 multiplied by the market value. The formula for the price at which a margin call is triggered is: Margin call price = Purchase price per share × (1 − Initial margin) / (1 − Maintenance margin).
Plugging in the numbers: $50 × (1 − 0.50) / (1 − 0.30) = $50 × 0.50 / 0.70 = $35.71.
If the stock price falls to $35.71, the 400 shares are worth $14,284. The loan remains $10,000, so equity is $4,284. The maintenance requirement is 30% of $14,284, which is $4,285.20. Equity has fallen just below the threshold, triggering a margin call. The trader must deposit at least enough to bring equity back to 30% of the market value, or the broker may sell shares. If the price drops further to $30, the position is worth $12,000, equity is $2,000, and the trader faces a substantial shortfall. The broker can liquidate the position, and the trader still owes any remaining loan balance after the sale.
Margin loans accrue interest daily, and rates vary by broker and loan size. A typical margin rate might be quoted as a base rate plus a spread, often ranging from 6% to 12% annually depending on market conditions. On a $10,000 loan at 8% annual interest, the daily interest cost is roughly $2.19. Over a year, that is $800 in interest, which eats into returns. Margin trading is generally suited for short- to medium-term trades because the interest cost compounds over time. A position that moves sideways for months can generate a loss purely from interest expenses.
Short selling, which profits from a price decline, requires a margin account. The trader borrows shares from the broker and sells them, hoping to buy them back later at a lower price. The proceeds from the short sale are held as collateral, and the trader must deposit additional margin, typically 50% of the short sale value initially. The maintenance margin for short positions is often 30%. If the stock price rises, the trader faces potentially unlimited losses and may face a margin call requiring additional funds.
Margin trading amplifies risk. A 50% decline in a fully cash-funded position results in a 50% loss. With 2:1 leverage, the same decline wipes out 100% of the trader's capital. Beyond equities, margin is used in forex, CFDs, and crypto trading, where leverage can be significantly higher. Forex brokers may offer 30:1 or 50:1 leverage in regulated jurisdictions, and crypto exchanges sometimes offer 100:1 or more. At 100:1 leverage, a 1% adverse move eliminates the entire margin deposit. These products are not suitable for beginners. Liquidation can happen in seconds during volatile markets, and negative balance protection is not guaranteed in all jurisdictions. Traders should never risk more than they can afford to lose and should use stop-loss orders to define maximum loss per trade. A prudent approach is to limit total borrowed funds to a fraction of the account, such as never exceeding 20% to 30% of available margin, and to monitor positions daily.
Prepared with AlphaScala editorial tooling, examples, and risk-context checks against our education standards. General education only, not personalized financial advice.