What Is a Margin Call? A Plain-English Explanation With an Example
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A margin call is a demand from your broker to add cash or securities to your account because your equity has fallen below the minimum required to keep borrowing. If you don't meet it, the broker can sell your positions to repay the loan, often without asking first and at whatever price the market offers.
It only applies if you trade on margin, meaning with money borrowed from your broker, so a regular cash account can lose value but can never receive a margin call.
How margin works
A margin account lets you buy more than your own cash would allow. In the US, the Federal Reserve's Regulation T generally lets you borrow up to 50 percent of the purchase price of eligible stocks, which means $10,000 of your own money could buy $20,000 worth of stock.
The catch is that your broker keeps watching the ratio between what you own outright and the total value of the position, which is your equity percentage. FINRA sets a floor called the maintenance margin requirement at 25 percent of market value for most stocks, and many brokers set their own house requirement higher, commonly at 30 to 40 percent and higher still for volatile or concentrated positions.
A worked example
Say you buy $20,000 of stock using $10,000 of your own money and $10,000 borrowed, and your broker's maintenance requirement is 25 percent.
- At the start the position is worth $20,000 and you owe $10,000, so your equity is $10,000, or 50 percent.
- If the stock falls 20 percent, the position is worth $16,000 while you still owe $10,000, leaving equity of $6,000, or 37.5 percent, which is still above the line.
- If the stock keeps sliding to a total drop of about 33 percent, the position is worth roughly $13,333 and your equity of about $3,333 sits right at 25 percent.
- Any further decline from there triggers a margin call.
Look at what the leverage did. The stock fell by a third, but your own money fell by two thirds, from $10,000 to about $3,333, because the loan doesn't shrink when prices drop and only your share does.
What happens when you get one
You'll usually be asked to bring the account back above the requirement by depositing cash, depositing marginable securities or selling some positions. Brokers often allow a few days for this, but they aren't obliged to, and most margin agreements let the broker sell your holdings without notice, choose which ones to sell and do it at any time while the account is under the minimum. In a fast market, that's exactly what tends to happen.
The cruel part is that margin calls arrive after prices have already dropped, so forced selling tends to lock in losses near the lows, and if the market then recovers, the position that would have come back is already gone.
Margin calls outside of stocks
The idea is the same across markets, even though the vocabulary changes.
Forex and CFDs: brokers usually show your margin level as a percentage, sending a margin call warning when it drops below one threshold and automatically closing positions once it falls below a lower stop-out level, often starting with the biggest loser.
Futures: exchanges set initial and maintenance margin and mark accounts to market every day, so if you drop below maintenance you'll need to top the account back up, usually quickly.
Crypto derivatives: many exchanges skip the polite call altogether and liquidate your position once it hits a set price, and with high leverage that price can sit uncomfortably close to your entry.
Why margin calls cluster in bad markets
When prices drop sharply, lots of leveraged accounts hit their limits at the same time, and the forced selling from one wave of margin calls pushes prices lower, which then triggers the next wave. That cascade is part of why sell-offs can feel so violent, and why people argue afterwards about whether the snap-back was a dead cat bounce or a genuine dip. It's closely related to the stop hunt, since both involve piles of forced orders that can push the price further than the news alone would.
How people avoid them
Use less leverage than you're allowed. Being able to borrow 50 percent doesn't mean you should, and the less you borrow, the further prices have to fall before a call arrives.
Know your trigger price. Before you enter, work out the price at which your account would hit maintenance, and if that number makes you nervous, the position is probably too big.
Keep a cash buffer. Spare cash sitting in the account itself, rather than in a savings app that takes days to move, gives you room when you need it.
Set your own exit above the broker's. A planned stop loss well before the margin line means you choose where to get out instead of letting the broker choose for you.
Watch concentration. One volatile stock on margin is much riskier than a spread of positions, and brokers often raise requirements on exactly those stocks when volatility jumps.
Don't add to a loser to defend it. Borrowing more to average down on a falling position is how a manageable drawdown becomes a margin call, and the urge to win it back quickly is the same pull that drives FOMO, just pointed in the other direction.
The habit that matters most is writing those numbers down at entry, and a trading journal with a field for planned risk on every position makes it obvious when you've drifted into borrowing more than you meant to.
The short version
A margin call is the moment borrowed money stops being invisible. It rarely comes down to bad luck and usually means the position was sized only for the market going your way. For the rest of the vocabulary around leverage, liquidity and stops, our trader slang glossary is a good next read.
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Educational content only, not financial advice. Nothing here is a recommendation to buy or sell any asset. Markets carry risk, including total loss.