Lesson 4 of 5 · 2 min
0DTE and expiry days
What same-day options are, when the big expiries happen, and why those days can feel different.
What 0DTE means
0DTE stands for "zero days to expiration": options that expire today. S&P 500 index options (SPX) and big ETFs like SPY and QQQ now have expiries every weekday, so there's always a 0DTE option somewhere. They've become a large share of daily options volume.
Because they expire within hours, 0DTE options are cheap and extremely sensitive to small moves. In Greek terms, their gamma is huge.
The calendar's big days
- Monthly expiry (OPEX): the third Friday of each month. Standard monthly options expire, and there's a lot of open interest at once.
- Quarterly expiry: the third Friday of March, June, September and December. Index options and the ES/NQ futures themselves expire around the same time. It's sometimes called quad witching.
Why expiry days can feel different
- Gamma is at its highest, so dealers' hedges have to change faster. That can mean more buying and selling around big strikes.
- Price sometimes seems pulled toward a large strike into expiry (often called "pinning"), then moves more freely once those options are gone.
- After a big expiry, a lot of hedging disappears at once. The next day can behave differently.
Description, not a rule
These are tendencies people observe, not guarantees. This lesson is here so the words make sense. It isn't a reason to trade a certain way on expiry days.
Quick recap
- 0DTE = options expiring today. Huge gamma.
- Monthly OPEX is the third Friday. Quarterly expiries fall in Mar/Jun/Sep/Dec.
- Expiry days can feel different because hedging changes fast.
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