What Is Margin in Trading? A Plain-English Guide

Margin lets you control more capital than you actually own. That sounds attractive until you understand what happens when the trade goes against you — and how fast it can happen.

What margin actually is

At its core, margin is collateral. When you trade on margin, your broker lends you money to buy securities, and you pledge a portion of your own capital as a deposit against that loan. The position you control is larger than the cash you put up; the difference is the broker's money, and they want it back.

Margin is not free leverage. It is a loan. Like any loan, it carries cost (margin interest), conditions (maintenance requirements), and consequences if you cannot service it (forced liquidation).

The term "margin" appears in two related but distinct meanings in trading:

• The deposit you put up — sometimes called the margin requirement or required margin.
• The equity remaining in your account — your account's margin, which rises and falls with your positions.

Both meanings appear constantly. Context usually makes clear which one a broker or article is using.

Margin accounts vs cash accounts

Before you can trade on margin, you need a margin account. This is different from a standard cash account:

Cash accounts keep things simple. You can only spend what you have, and you cannot lose more than you deposit. Margin accounts give you more firepower but introduce the possibility of losses that exceed your deposit — your losses come first before the broker's loan is touched.

Initial margin: the cost to get in

Initial margin is the percentage of a position's value you must fund yourself to open the trade. In the US, Regulation T (Reg T) sets the minimum for most stocks at 50% — meaning you can borrow up to half the purchase price.

initial margin required = position value × initial margin rate

Buy $20,000 of stock on 50% initial margin: you put up $10,000 and the broker provides the other $10,000.

Brokers are allowed to set their own initial margin requirements above the regulatory minimum. For volatile stocks or concentrated positions, many do exactly that.

Maintenance margin: the floor you cannot fall through

Once the position is open, initial margin no longer matters — maintenance margin takes over. Maintenance margin is the minimum equity you must keep in the account to hold the position open.

As the position moves against you, your equity shrinks while the broker's loan stays fixed. When your equity falls below the maintenance threshold, you get a margin call. Either you add funds to bring equity back above the requirement, or the broker liquidates part or all of your position to recover the loan.

The FINRA minimum maintenance rate for US stocks is 25%, but most brokers require 30% or more. For the full formula and the exact price that triggers a call, see the maintenance margin deep dive.

A worked example: stock bought on 50% margin

You buy 200 shares at $100 each — a $20,000 position — on 50% initial margin.

• Your equity at entry: $10,000
• Broker loan: $10,000 (stays fixed)
• Maintenance rate: 25%

As the stock falls, the loan stays at $10,000 while the position's market value drops:

At $66.67 your equity exactly equals 25% of the position value. Any further drop and the broker has grounds to liquidate. A 33% fall in the stock price is enough to trigger the call — even though you only borrowed 50%.

Drop your own numbers in here to see the margin call price for any position:

You can also use the Margin Calculator directly anytime.

How leverage connects to margin

Margin and leverage are two sides of the same concept. Margin is expressed as a percentage; leverage is expressed as a ratio. They convert into each other:

leverage ratio = 1 ÷ margin rate

A 50% margin requirement means 2:1 leverage — you control $2 for every $1 of your own capital. A 10% margin requirement gives 10:1 leverage.

Higher leverage amplifies returns in both directions by the same multiple. With 5:1 leverage, a 10% move in the underlying becomes a 50% move in your equity — positive or negative. For a precise comparison of the two concepts, see Leverage vs Margin.

Margin in different markets

The 50%/25% stock framework above is US equities under Reg T. Other markets work differently:

Forex and CFDs

Forex brokers express margin as a small percentage of notional value — 1% margin for 100:1 leverage is common in retail FX outside the US. Many platforms track your position using a margin level (equity divided by used margin, expressed as a percentage). Fall below 100% and an automatic stop-out closes positions to protect the broker.

Futures

Futures margin is not a loan at all — it is a performance bond. The exchange sets a fixed dollar amount per contract (initial and maintenance levels). When your account drops below the maintenance level, you must restore it to the full initial level, not just back above maintenance. This distinction matters: a futures margin call demands more than the bare minimum to get you compliant.

Options

Buying options requires no margin — you pay the premium outright and that is the most you can lose. Selling (writing) options is different. Naked short options require margin because the potential loss is theoretically unlimited (for short calls) or very large (for short puts).

The risks: why margin discipline matters

Margin amplifies losses just as readily as gains, and it adds at least two risks that cash-account traders never face:

Forced liquidation at the worst moment. A margin call typically arrives after a sharp adverse move, precisely when sentiment is worst and spreads are widest. Brokers can and do liquidate positions without waiting for your input. You may be sold out at the low.

Interest compounds against you. Margin loans carry daily interest. Hold a losing margined position for weeks and you pay interest on a position that is already hurting you.

You can lose more than you deposited. If the position gaps down overnight past the maintenance threshold and the broker cannot liquidate in time, your account can go negative. You owe the broker the shortfall.

These are not reasons to never use margin. They are reasons to size positions so a normal adverse move does not threaten the maintenance floor.

Sizing around the margin requirement

A common mistake is treating margin buying power as an instruction rather than a limit. Just because the account lets you take a $100,000 position does not mean that position fits your risk tolerance.

A more disciplined approach:

1. Decide the dollar risk first. How much are you willing to lose on this trade if you are wrong? Use the Position Size Calculator to translate that risk into a position size before margin enters the picture.
2. Set the stop before you enter. Know the exit price, not just the margin-call price. The Stop Loss Calculator helps place the stop where the trade is invalidated, well before the broker's margin call price.
3. Check the margin call price. Confirm that your planned stop would take you out before the maintenance floor. If the stop is below the margin call price, the broker exits before you do — on their terms, not yours.

For the formulas behind these calculations, see The Margin Equation Explained.

Summary

Margin is a tool. Used with clear position sizing and a pre-set stop, it lets you take meaningful positions without tying up capital unnecessarily. Used without those guardrails, it turns ordinary drawdowns into account-ending events.

Before you trade on margin, know your maintenance margin, know the price that triggers the call, and make sure your stop gets you out first. The Margin Calculator runs those numbers in seconds.

Disclaimer

This article is for educational purposes only and does not constitute investment advice. Margin rules, rates, and requirements vary by broker, instrument, and jurisdiction — always confirm the exact terms with your broker before trading. Trading on margin amplifies both gains and losses and carries a real risk of losing more than your initial deposit.