What is a Margin Requirement? Definition, Formula, and Example
A margin requirement is the minimum equity a trader must hold in a margin account to open or maintain a leveraged position.
What is a Margin Requirement?
A margin requirement is the minimum amount of equity a trader must deposit in a margin account to open or maintain a leveraged position. It functions as collateral that the broker holds against potential losses. Requirements exist at two stages: initial margin, which is the equity needed to open a new position, and maintenance margin, which is the minimum equity that must remain while the position is open. If account equity falls below maintenance margin, the broker issues a margin call and may liquidate positions without notice.
How It Is Calculated
For long equity positions under Regulation T, the initial margin requirement is typically 50 percent of the purchase price, meaning the trader must fund half the trade with cash and may borrow the remainder. Maintenance margin is set by FINRA at a minimum of 25 percent of the current market value of the securities, though brokers often require 30 percent to 40 percent for volatile stocks. The formula for equity in a long margin account is:
Equity = Current market value of securities − Margin loan balance
Margin percentage = Equity / Current market value
Short sale margin requirements under Regulation T are 150 percent of the current market value of the shorted securities: 100 percent of the sale proceeds plus an additional 50 percent as margin. Maintenance requirements for short positions are generally 30 percent of current market value.
Worked Example
A trader wants to buy 1,000 shares of NVDA at $120 per share. The total purchase value is $120,000. Under Regulation T, the initial margin requirement is 50 percent, or $60,000. The broker lends the remaining $60,000.
If NVDA rises to $150, the position is worth $150,000. Equity is $150,000 minus the $60,000 loan, or $90,000. The margin percentage is $90,000 / $150,000, or 60 percent, well above maintenance.
If NVDA falls to $70, the position is worth $70,000. Equity is $70,000 minus $60,000, or $10,000. The margin percentage is $10,000 / $70,000, or approximately 14.3 percent. Because this is below a typical 30 percent maintenance requirement, the broker issues a margin call. The trader must deposit additional cash or sell shares to restore equity to the required level.
When Traders Use It
Traders check margin requirements before sizing leveraged equity, options, and futures trades. Initial margin determines how much buying power a trade consumes. Maintenance margin determines how much adverse price movement an account can absorb before forced liquidation. Day traders and swing traders monitor margin usage intraday to avoid margin calls during volatile sessions. the live scanner
Limitations and Common Misconceptions
Margin requirements are not static. Brokers can raise house requirements at any time, especially ahead of earnings or during market stress, and changes often apply immediately to existing positions. A margin call does not always come with a grace period; brokers may liquidate positions without contacting the client. Maintenance margin is based on current market value, not the original purchase price, so a rally does not permanently cushion a position if the price later retreats. Margin interest accrues daily on the loan balance and reduces net returns over time.