What is automatic exercise?
In one line: Automatic exercise is the rule that an option in the money by $0.01 or more at expiry is exercised for the holder unless they say otherwise, so the seller is assigned.
How it works
At expiry, the clearing house runs a simple rule for US stock options. If an option is In the money by $0.01 or more at the close, it's exercised for the holder. They don't have to click anything. This is often called "exercise by exception."
For the seller, that means Assignment. A sold put that ends a cent in the money hands you 100 shares at the strike. A sold call that ends a cent in the money takes 100 shares away.
The holder can opt out with a "do not exercise" instruction, and can also choose to exercise an option that's slightly out of the money. Brokers set their own deadlines for those instructions, and some close positions themselves near expiry if an account can't cover the shares. Check your broker's current rules.
An example (hypothetical)
You sold a $45 put on XYZ for $0.80 and collected $80 (an illustration, not a trade idea). It's expiry Friday. Over the weekend, XYZ has bad news and opens Monday at $41.
| XYZ at Friday's close | What happens | Your result on Monday |
|---|---|---|
| $45.50 | Out of the money. Expires | +$80 |
| $45.00 | At the money. Not automatic; the holder may or may not exercise | +$80, or −$320 if assigned |
| $44.99 | In the money by a cent. Exercised for the holder. You're assigned | −$400 + $80 = −$320 |
| $44.00 | In the money. Exercised. You're assigned | −$400 + $80 = −$320 |
The $44.99 row is the one that surprises people. "It's only a penny" doesn't matter. A penny in the money means you buy 100 shares at $45 ($4,500). Then the weekend moves the price, and the loss is set by Monday's open, not Friday's close.
Why it matters for sellers
Automatic exercise turns a near miss into a full position. Three habits help:
- Don't leave it to the last cent. If your option is near the strike on expiry day, decide: buy it back for a few cents, or accept the shares on purpose.
- Have the cash or shares. In a cash-secured put, the cash is set aside. On margin, a surprise assignment can trigger a margin call.
- Know the close is not the end. After-hours news can change whether a holder exercises. That's Pin risk.
Buyers get surprised too. A long call a cent in the money at expiry becomes 100 shares, which can cost far more than the account holds.
In the wheel strategy, being assigned is often fine, but it should be your choice, not a penny's. See options expired in the money by a penny for what to do the next morning.
Questions
Is automatic exercise the same everywhere?
The cent-in-the-money rule is the US standard for stock options. Brokers can add their own policies on top, so check yours.
Can I stop my option from being exercised automatically?
If you hold the option, you can usually send a "do not exercise" instruction before your broker's deadline. If you sold it, you can't stop it. Buy it back before the close instead.
What if I can't afford the shares?
Your broker may close the position before expiry, or you may get a margin call after assignment. Don't count on the broker to fix it. Close the trade yourself.
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