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What are the odds my option gets assigned?
The rough odds your short option ends in the money, and gets assigned, are close to its delta. The odds the stock touches your strike before expiry are about twice that. Here's how to use both numbers.
The short answer
For a short option held to expiry, the chance of Assignment is about the chance it ends in the money. A quick guide to that is the option's Delta: a 0.30-delta put is roughly a 30% chance.
The chance the stock touches your strike at some point before expiry is higher, roughly double. So a 0.30-delta put has something like a 60% chance of being tested, even though it ends in the money only about a third of the time.
Both numbers come from a pricing model using the market's own volatility guess. They're rough odds, not forecasts.
Ending in the money vs touching the strike
These are different events, and they lead to different decisions.
- Ending in the money is what decides assignment at expiry. The stock is below your put strike (or above your call strike) at the close on the last day.
- Touching the strike is the stock trading through your strike at any time before expiry. It might come back. If you have a rule like "close when the strike is hit," this is the number that matters.
Why is touching about double? Picture the stock right at your strike halfway through the trade. From there, it's roughly a coin flip whether it ends above or below. So for every path that touches and ends in the money, there's about one that touches and recovers.
A worked example (an illustration, not a trade idea)
A made-up stock, XYZ, trades at $50. Implied volatility is 30%. Here's a 30-day put ladder with rough model numbers.
| Put strike | Delta | Model odds of ending in the money | Rough odds of touching first |
|---|---|---|---|
| $50 | 0.47 | About 50% | Very high, near certain |
| $49 | 0.38 | About 41% | About 80% |
| $48 | 0.29 | About 32% | About 64% |
| $47 | 0.21 | About 24% | About 48% |
| $46 | 0.15 | About 17% | About 34% |
For puts, delta runs a little below the model's odds of ending in the money. For calls it runs a little above. That's why it's a rough guide. Your broker may also show a "probability ITM" column that's more exact.
What assignment costs, in dollars
Odds tell you how often. Dollars tell you how much. You sell the $48 put for $0.80 and collect $80. Your broker sets aside $4,800.
| XYZ at expiry | What happens | Shares | Premium | Total result |
|---|---|---|---|---|
| $52 | Put expires | — | +$80 | +$80 |
| $48.50 | Put expires, though it was touched earlier | — | +$80 | +$80 |
| $47.20 | Assigned at $48 | −$80 | +$80 | $0 (break-even) |
| $46 | Assigned at $48 | −$200 | +$80 | −$120 |
| $44 | Assigned at $48 | −$400 | +$80 | −$320 |
About a third of trades like this end in the money if the market's volatility guess is right. Many of those end in a loss like the $44 row. About two in three get tested first, which is when you'll feel like doing something. That's a math example, not a promise.
Early assignment: the other path
US stock options can be exercised any day, so assignment can come before expiry. It's less common than people fear, but it has clear triggers.
- Deep in the money with little time value left. The buyer gives up almost nothing by exercising early.
- Calls before an Ex-dividend date. If the call's time value is less than the dividend, a buyer may exercise to collect the dividend.
- Puts deep in the money. A put holder may exercise to get their cash now rather than wait.
If your short option is out of the money, early assignment is very unlikely. Once it's in the money, check how much time value is left. Intrinsic vs extrinsic value for sellers shows how.
How to use the odds
Pick a strike by how often you're happy to be assigned. In the wheel strategy, assignment on a put isn't a failure: it's step two. If you'd be glad to own the shares, a higher delta is fine. If you'd rather keep collecting, go lower.
Plan for the touch, not just the finish. If the touch odds are 60%, you'll probably see your strike tested. Decide now what you'll do: hold, roll, or close. Make that decision before the stock is there.
Use the dollar table to size. A 17% chance sounds small. But if it happens, you're buying 100 shares in a falling stock. Size every trade as if assignment were certain. See sizing math, the full obligation rule.
In plain words: delta says how often you'll end up with the shares, roughly. The touch odds say how often you'll be nervous. Neither says how big the loss gets.
Where the odds go wrong
- The market's volatility guess is off. Earnings, news and crashes can move a stock more than priced.
- The odds change every day. A drop toward your strike can take a 30% chance to 60% fast, especially near expiry. See gamma risk for option sellers.
- Model odds aren't real-world odds. The model assumes no view on direction. Real stocks trend, gap and stall.
Our options assignment probability calculator lets you try your own strike and volatility.
Questions
Does delta equal the probability of assignment?
Roughly, for an option held to expiry. Delta is close to the model's odds of ending in the money. For puts it's a little low, for calls a little high. It doesn't cover early assignment, which depends on time value and dividends.
Why is the chance of touching the strike higher?
Because a stock can trade through your strike and come back before expiry. Roughly half the paths that touch end back on your side, so touching is about twice as likely as finishing in the money.
How often do cash-secured puts get assigned?
It depends on the strike, the time left and how the stock moves. A 0.20 to 0.30 delta put has rough model odds of 20% to 30% at expiry. Our guide on how often cash-secured puts get assigned goes further.
Can I lower my chance of assignment?
Yes, by picking a lower-delta strike, a shorter expiry or by closing early. Each option lowers your premium too. Assignment odds and premium always move together.
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