Options Margin Calls: What Happens and How to Avoid Them
A margin call is your broker telling you: "Your account doesn't have enough money to support your open positions. Add cash or we'll start closing things for you." It's one of the most stressful events in trading, and it almost always happens at the worst possible moment — when the market is dropping and your positions need the most room to recover.
How Margin Works for Options
When you sell options, your broker requires margin — a deposit that ensures you can cover potential losses. The margin requirement varies by strategy:
Defined risk (credit spreads, iron condors): Margin equals the max loss of the position. A $5-wide credit spread requires $500 of margin per contract, minus the credit received.
Undefined risk (naked puts, short strangles): Margin is calculated using a formula that considers the stock price, strike price, and option premium. It's typically 20% of the underlying value plus the option premium, minus any out-of-the-money amount. This requirement can increase as the position moves against you.
Cash-secured puts: In a cash account, you need the full strike price × 100 in cash. In a margin account, the requirement is lower but still substantial.
What Triggers a Margin Call
A margin call occurs when your account equity falls below the maintenance margin requirement. Common triggers:
A big move against your short options. If you sold SPY puts and the market drops 3%, the margin requirement on those puts increases because they're closer to being in-the-money. Your account equity drops (unrealized losses) while your margin requirement rises. The squeeze from both directions is what causes the call.
Multiple positions moving against you simultaneously. Even if each position is properly sized, correlated losses across several positions can collectively push your account below the maintenance level.
Dividend or corporate action. If you're short calls on a stock that declares a special dividend, the margin requirement can change unexpectedly.
IV expansion. A market panic can inflate implied volatility across the board, increasing the margin requirement on all your short positions even before the underlying moves significantly.
What Happens When You Get a Margin Call
Step 1: Your broker notifies you. Usually via email, app notification, or platform alert. You typically get 2-5 business days to resolve it, though this varies by broker and severity.
Step 2: You can add funds. Deposit enough cash to bring your account above the maintenance requirement.
Step 3: You can close positions. Sell or buy back positions to reduce your margin requirement.
Step 4: If you don't act, the broker acts for you. They will liquidate positions — often at the worst possible prices — until your account meets the margin requirement. They choose which positions to close, not you. They often pick the most liquid positions, which might be your best trades.
How to Avoid Margin Calls
Rule 1: Never use more than 50% of your buying power. This is the single most important rule. If you have $100,000 in buying power, never commit more than $50,000 to positions. The remaining $50,000 is your buffer against adverse moves.
Rule 2: Know your worst-case margin requirement. The initial margin requirement for a naked put is one thing. The maintenance margin if the stock drops 10% is another, much larger number. Calculate what happens to your margin if all positions move against you by 1 standard deviation simultaneously.
Rule 3: Limit undefined-risk exposure. Every naked option in your account is a potential margin expansion bomb. If you sell undefined-risk positions, keep them to a small portion of your portfolio and monitor them closely.
Rule 4: Monitor buying power daily. Check your buying power every morning. If it's dropped below 40% of your account value, start reducing positions before you're forced to.
Rule 5: Reduce positions before known events. Before earnings, FOMC meetings, or other volatility catalysts, reduce your exposure. Margin requirements often spike after these events.
The Margin Call Recovery Trap
Many traders, after receiving a margin call, close their largest losing position to free up margin. This locks in the maximum loss on that trade. Often, if they'd had the margin room, that position would have recovered.
This is why prevention is everything. A margin call doesn't just cost you the closed position's loss — it costs you the recovery on that position.
Margin Call Prevention Checklist
OptionsPilot helps you monitor your positions and their risk profiles in one place, making it easier to spot margin pressure building before it becomes a crisis.