Margin

In trading, margin is the collateral, cash, or account equity required to open, maintain, or finance a leveraged position. It is not the same as a company’s profit margin; here the term refers to broker, exchange, or clearinghouse requirements that support trading exposure.

Margin matters because it controls how much exposure an account can carry, how quickly losses can force action, and whether a broker or clearing firm can demand more collateral or liquidate positions. This page is general financial education, not individualized investment, tax, or regulatory advice.

Key Takeaways

• Margin is a risk-control and funding concept, not a trading signal.
• In a securities margin account, the investor’s equity supports a broker loan.
• In futures and some derivatives markets, margin is performance collateral rather than a loan used to buy the full contract.
• Requirements can change because of price moves, volatility, concentration, product rules, broker house rules, or market stress.
• A margin position can lose more than the investor’s initial cash deposit.

Types Of Margin

Simple Example

Suppose an investor buys $10,000 of stock with $5,000 of cash and a $5,000 margin loan. If the stock falls to $8,000, the loan is still $5,000 before interest, so the investor’s account equity is $3,000.

The stock fell 20%, but the investor’s equity fell from $5,000 to $3,000, a 40% decline before commissions, interest, and taxes. If the decline continues, the broker may require more equity or sell securities to reduce the loan.

What Can Change The Requirement?

Margin is not a single fixed number. A requirement can change when:

• the market value of collateral rises or falls
• the position is concentrated in one security or sector
• a security becomes hard to borrow, thinly traded, or less eligible for margin
• the broker applies stricter house requirements
• exchange or clearinghouse margin models react to volatility
• the account is used for short selling, options, futures, or other leveraged products

Common Mistakes

• Treating buying power as cash that cannot disappear.
• Ignoring margin interest when comparing a leveraged trade with a cash trade.
• Assuming a broker must wait for the investor to approve a liquidation.
• Confusing trading margin with company gross margin or net profit margin, which are financial-statement ratios.
• Using margin because exposure is available rather than because the trade has a defined risk plan.

Official Sources

• SEC: Margin, Borrowing Money to Pay for Stocks
• FINRA Rule 4210: Margin Requirements
• Federal Reserve: Regulation T background

Related Terms

• Margin Account: Brokerage account that permits borrowing against eligible securities.
• Buying on Margin: Purchasing securities with investor equity plus broker credit.
• Margin Loan: Broker loan secured by securities in the margin account.
• Buying Power (Excess Equity): Broker-calculated capacity for additional trading or borrowing.
• Initial Margin: Equity or collateral required to open a margin position.
• Maintenance Margin: Equity or collateral required to keep a margin position open.
• Margin Call: Broker demand to add equity or reduce exposure.