Explainer · Options
How Much Can You Lose Selling a Put?
Selling a put has a fixed worst case you can calculate before the order goes in. The losses that actually hurt usually come from a gap, and you can price that ahead of time too.
Short answer
The most you can lose selling a put is the strike times 100, minus the premium you collected, per contract. You only reach it if the stock goes to zero: sell a 30 put for $1.20 and the worst case is $2,880. Realistic losses come from a gap well below the strike.
The order ticket looks harmless. Sell to open, one contract, the 30 put on a hypothetical stock, limit $1.20. When it fills, $120 lands in your account. What the ticket doesn’t spell out is the promise you just made in exchange: you’ve agreed to buy 100 shares at $30 each if the option holder exercises, which is $3,000 of stock, wherever the shares happen to trade that day.
What’s the worst case on a short put?
The stock goes to zero. You pay $3,000 for shares worth nothing. The premium softens that a little.
Per contract, that’s strike x 100 minus premium. Above $28.80 at expiration the trade makes money, and below it each dollar the stock falls costs you another $100 per contract, all the way down to a share price of zero, which is where the $2,880 comes from.
That floor is the one comfort. A put’s loss has a limit because a share price can’t go below zero, which is why a short put is a far easier risk to measure than a short call, where the stock can keep rising with nothing to stop it.
How does the worst case compare with the best case?
The best case is keeping the $120. That happens when the stock finishes above $30 at expiration and the put expires worthless. So the trade puts up to $2,880 at risk to earn $120, a ratio of 24 to 1.
The stock usually won’t go to zero. The shape still matters. One bad outcome, like the gap further down, can wipe out the premium from several quiet trades at once.
Does a margin account change how much you can lose?
The loss stays the same. What changes is how much cash you tie up.
In a cash-secured put, the broker holds back enough cash to buy the shares if you’re assigned, so the $3,000 obligation is funded from the start. A margin account lets you sell the same put while posting only part of that as collateral, under a formula your broker sets, which frees cash for other trades and changes nothing about what happens if the company fails. At zero you still owe $3,000. You still kept only $120.
The danger sits in what the smaller requirement lets you do. Say your margin rules let you sell five puts with the cash that would secure one: you’d be carrying five times the worst case, $14,400, on an account that looked, from its buying power line, perfectly comfortable the day before.
What does a realistic bad case look like?
Stocks rarely go to zero while you’re short a put. The losses sellers actually take come from gaps. The company reports after the close, or news lands overnight, and the stock opens well below your strike without trading at any price in between, so there’s no moment when a stop could have gotten you out near $28.80.
Say it opens at $24.
That’s four times the premium you collected. The ratio between what a normal week pays you and what a bad week costs you is the number to look at before you sell, and pricing the bad week before selling puts walks through why it matters more than the premium.
A gap also makes assignment likely. If the holder exercises early, you own 100 shares at $30 on the spot. Early assignment doesn’t change the loss at that moment. What it does is swap the option for 100 shares. Shares have no expiration date, so the loss can keep growing after the day the put would have run out, unless you sell them or have a plan for owning them.
How do you limit the loss?
There are two practical ways, and they can be combined.
The first is a spread. Buy a lower-strike put in the same expiration and your worst case becomes the distance between the strikes times 100, minus the net credit, a number you know to the dollar before the order goes in. The catch is that it pays less. You spent part of the premium on the long leg.
The second is sizing. Decide the largest loss you’ll accept on the trade, then count contracts from the worst case you’ve chosen to plan for, whether that’s the $2,880 floor, the spread’s defined risk, or a gap to a price you think is plausible.
Test a few prices below the strike in the options profit calculator first. More on short options and how they fail sits on the options desk.
Readers also ask
What happens if a put you sold gets assigned?
Each assigned contract makes you the buyer of 100 shares at the strike, paid from your account's cash or margin. From then on you hold stock, with the premium you collected lowering your effective cost. You can sell the shares, keep them, or sell calls against them.
Do you need a margin account to sell puts?
Not always. Brokers commonly allow cash-secured puts in a cash account, as long as the full cost of buying the shares at the strike is held in cash. Selling puts without that cash set aside needs a margin account and a higher options approval level, and the requirements vary by broker.
Is selling a cash-secured put riskier than buying the stock?
The downside is close to owning 100 shares bought at the strike, reduced by the premium. The upside is where they part: shares keep gaining as the stock climbs, and a short put can earn no more than the premium. The risk is similar to owning the stock and the reward is capped, which is the trade-off to weigh.