What is OpEx?
In one line: OpEx, short for options expiration, is the day a set of options contracts expire, most often the third Friday of the month for standard US monthly options.
How it works
OpEx is trader shorthand for options expiration. Usually it means the monthly one: the third Friday of each month, when standard US stock options expire. If that Friday is a market holiday, expiry moves to Thursday.
There are other expiry days too. Weekly options expire on most other Fridays. Some index and ETF products have options expiring every weekday. But "OpEx" usually points at the big monthly date.
At the close on expiry day, options in the money by a penny or more are usually exercised automatically. Those out of the money expire worthless. Holders have until a cutoff that evening to give other instructions, so final results can come in after the bell.
An example (hypothetical)
You bought XYZ at $52 and later sold a $50 Covered call on it for $1.00 (an illustration, not a trade idea). It's OpEx Friday. XYZ trades between $49.80 and $50.20 all afternoon.
| XYZ at the close | What likely happens | Result |
|---|---|---|
| $49.90 | Call expires; you keep the shares | −$110 on paper (−$210 on shares, +$100) |
| $50.10 | Shares called away at $50 | −$100 (−$200 on shares, +$100) |
| Under $50 at the close, above it after hours | The holder may still exercise | You find out Monday whether the shares are gone |
That last row is Pin risk. When a stock closes right at your strike, you can't be sure you'll be assigned until later. A math example, not a promise.
Why it matters for sellers
OpEx days often bring more trading, because many traders close or roll positions before the bell. Some traders also notice prices settling near strikes with lots of Open interest. That's called "pinning." It doesn't happen every time, and it isn't something to bet on.
For the wheel strategy, OpEx is a decision day. Know your plan before Friday: let it expire, buy it back, roll it, or take the assignment. If the stock is near your strike in the last hour, closing the option removes the guesswork.
Options lose time value fastest in these final days. Our theta decay guide explains why.
Questions
What time do options expire on OpEx?
Standard US stock options stop trading at the 4:00 p.m. Eastern close on expiry day. Holders can still decide whether to exercise until a cutoff that evening, so check your broker's deadline.
Is OpEx always the third Friday?
For standard monthly options, yes, unless it's a holiday. Weekly and daily options have their own dates.
What's the difference between monthly and quarterly OpEx?
Quarterly OpEx is the monthly date in March, June, September and December. More kinds of contracts expire then, and it's often called Triple witching.
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