0DTE Options
Also called: zero days to expiration, 0DTE, same day options
0DTE options expire the same day they're traded, and they now make up roughly half of S&P 500 option volume. With hours to run, theta decay is brutal and gamma is enormous, so a small index move can multiply or destroy the premium in minutes. They are used institutionally for precise event hedges and retail for leveraged lottery tickets, and the concentration of dealer hedging they create has measurably increased intraday volatility.
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