Definition
Options bought and sold on the same day they expire.
The story
Because they expire within hours, 0DTE (zero days to expiration) options are cheap and react very sharply to small moves in the underlying index. Options on the S&P 500 now expire every trading day, and same-day contracts have become a large share of S&P 500 option trading.
Why markets watch it
Their popularity has become a regular topic in market coverage, including debate over whether heavy same-day trading adds to swings within the day.
Connects to
We explain why it moves markets. What you do with it is your call. Commentary and education only. Not financial advice. All terms