0DTE options
Also called zero days to expiry, 0DTE
0DTE options are contracts expiring the same trading day, whose extremely high gamma makes dealer hedging unusually sensitive to small moves in the underlying.
In more detail
An option’s gamma rises sharply as expiry approaches, so a same-day contract near the money can force far more hedging per point of movement than a longer-dated one. That concentrates hedging flow into a single session.
SPX lists 0DTE contracts every trading day, which is why intraday gamma analysis clusters around it. The effect is real but bounded — it shapes how a session moves rather than deciding direction.
How Hermes measures it
Hermes’s SPX tooling is built around the 0DTE session: intraday flow GEX and DEX by strike, net options flow, and net drift, all computed from same-session trades.
Read this on a live chart.
Hermes puts dealer positioning next to price through the session. Free to use.