Zero-day options—contracts that expire at the end of the same trading day—have exploded in popularity and now account for roughly 45% of SPX options volume. Because there is almost no time left to expiry, their gamma can change sharply as the index moves.
Dealers who take the other side of those trades do not want a directional bet. They continuously buy or sell ES and NQ futures to keep their exposure hedged. That creates a stream of mechanical market-maker flow around the strikes where options positioning is concentrated.
The opportunity is not to predict every move. It is to map where that forced buying and selling may appear, understand whether dealers are more likely to stabilise or amplify price, and use those levels as context for trading alongside the flow rather than blindly against it.