What is pin risk in options?
In one line: Pin risk is the uncertainty of whether a sold option will be assigned when the stock closes at or very near the strike on expiry day, so you don't know your position until after the weekend.
How it works
On expiry day, a stock sometimes closes almost exactly at a popular strike. It's "pinned" there. If you sold an option at that strike, you have a problem: you don't know if you'll be assigned.
Here's why. Automatic exercise only kicks in if the option is in the money by $0.01 or more. But holders can still choose to exercise an option that's just out of the money. And they have time after the 4 p.m. close to decide, up to their broker's cutoff.
So if bad news comes out after the bell, a put holder can still exercise a put that closed two cents out of the money. You find out Monday, when 100 shares show up in your account at a price that has already moved.
An example (hypothetical)
You sold a $45 put on XYZ for $1.00 and collected $100 (an illustration, not a trade idea). It's expiry Friday. XYZ closes at $45.02. You think the put expired. After the close, a news headline sends XYZ to $43 in after-hours trading. Monday it opens at $42.
| What you did Friday | What happened | Your result Monday |
|---|---|---|
| Left it open, closed at $45.02 | Holder exercised after hours. You're assigned at $45 | −$300 + $100 = −$200 |
| Left it open, closed at $45.02, no news | Put expired. No shares | +$100 |
| Bought it back Friday at 3:30 p.m. for $0.20 | Nothing to assign | +$100 − $20 = +$80 |
The first row is the Monday surprise. You thought you were done. You weren't. You owned 100 shares at $45 that opened at $42, and you had no chance to act over the weekend.
It works the other way too. A put that closes a cent in the money may be skipped by a holder if the stock jumps after hours, and the shares you expected never arrive.
Why it matters for sellers
Pin risk is small, but it's a surprise you can see coming. If your option is within a few cents of the strike in the last hour, you have two clean choices:
- Buy to close for a few cents and walk away with no doubt.
- Plan to own the shares (or have them called away) on purpose, with the cash or shares ready.
What you shouldn't do is leave it to chance and check on Monday. In the wheel strategy, assignment is often fine, but only when you've chosen it. Our pin risk explained guide covers the timing in more detail.
Questions
When does pin risk happen?
On expiry day, when the stock closes at or within a few cents of your strike. The closer it is, the less sure anyone is about exercise.
Can I be assigned on an option that closed out of the money?
Yes. Holders can choose to exercise an option that's slightly out of the money, often because of after-hours news. It's not automatic, but it happens.
How do I avoid pin risk?
Close the option before the market closes on expiry day when the stock is near your strike. The cost is usually a few cents a share.
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