Margin Call
A margin call is a broker's demand for more collateral when your equity falls too low. Learn what triggers one, what happens if you cannot meet it, and how to avoid it.
A margin call is a demand from your broker for more collateral, issued when your account equity falls below the required level. Meet it by adding funds or reducing positions, or the broker will close trades for you. It is the alarm bell that rings when a leveraged position has moved too far against you.
It is one of the most feared moments in trading, and understanding it removes much of the fear. Let me show you how it happens.
The Landlord Wants More Deposit
Recall that margin is a security deposit the broker holds against your trades. A margin call is the broker coming back to say the deposit is no longer enough.
When a position moves against you, your equity shrinks. If it drops below the maintenance margin, the floor you must stay above, the collateral no longer covers the risk. So the broker calls: top up the deposit, or we reduce the risk for you. It is not a punishment, it is the broker protecting itself from a loss bigger than your account can cover.
What Triggers One
A margin call comes from a mismatch between your equity and your requirement, and either side can move.
Losses erode your equity. The most common trigger: a position moves against you, your account value falls, and it slips below the maintenance floor. Short options and leveraged positions can get there fast in a sharp move.
The requirement rises. Margin is risk-based, so a spike in implied volatility can raise the collateral your positions demand, even if prices have not moved much. The floor rises to meet your shrinking cushion.
Either way, once your equity is below the requirement, the call is issued, often with a short deadline to act.
How to Meet It, and Avoid It
A margin call gives you a few ways out, and plenty of ways to prevent it in the first place.
Meeting it. You can deposit more cash or marginable securities to rebuild your equity, or close some positions to reduce the requirement. Do it promptly, because if you do not, the broker will liquidate positions of its choosing, frequently at the worst possible prices, and you have no say in what gets sold.
Avoiding it. The real skill is never getting the call. Keep a comfortable buffer above your maintenance requirement rather than trading at the edge of your margin. Size positions with your max loss in mind, and remember that selling uncovered options is the fastest route to a surprise call. A margin call is not bad luck; it is usually a sign the position was too large for the account.
- A margin call is the broker's demand for more collateral.
- It fires when equity falls below the maintenance requirement.
- Meet it by adding funds or closing positions, or face forced liquidation.
- Avoid it by keeping a buffer and sizing positions sensibly.
Pop Quiz
Three quick questions to see what stuck. Pick an answer and the explanation shows up right away.
What is a margin call?
It is the broker asking you to top up collateral because your equity fell below the requirement.
What happens if you do not meet a margin call?
If you cannot add funds or reduce risk, the broker forcibly closes positions of its choosing.
What is the best way to avoid margin calls?
A comfortable buffer and sensible sizing keep a normal move from ever pushing you below the floor.
Bottom Line
A margin call is the broker asking for more deposit because your equity has slipped below what your positions require. Meet it by adding funds or trimming risk; ignore it and the broker liquidates you, usually at ugly prices with no input from you.
The best defense is prevention. Keep a buffer above your maintenance requirement, size trades with your worst case in mind, and treat uncovered short options with respect. A margin call is almost always a symptom of a position that was simply too big.
Keep going: the floor it enforces is maintenance margin, the collateral behind it is margin requirements, and sizing to avoid it starts with position sizing.