When SPY gaps overnight, the whole dealer map resets, and the open becomes a battle around the prior-day high and low. The two scripts are gap-and-go (the gap runs) and gap-fill (price returns toward yesterday's close), and reading which is unfolding is the playbook.

Reading gap-and-go vs gap-fill

The prior-day levels are the tell. A gap up that holds above the prior-day high and builds is a gap-and-go — continuation. A gap up that rejects the prior-day high and falls back inside yesterday's range points to a gap-fill toward the prior close. The mirror applies to gap downs at the prior-day low. The reaction at the level, not the gap itself, is the signal.

The regime picks the base case

The regime weights the odds. In positive gamma, dealer hedging dampens and gaps tend to fill — fade the extension back toward yesterday's range. In negative gamma, moves amplify and gaps tend to run — respect the gap-and-go. Same gap, opposite lean, decided by the map.

The gap isn't the trade — the reaction to the prior-day level is. Hold above it and go; reject it and fill.

The entries

Gap-and-go: enter on a hold/reclaim of the prior-day level in the gap's direction, target the next level, stop back inside. Gap-fill: enter on the rejection at the prior-day level, target the prior close / VWAP, stop on acceptance beyond the level. Let the open build before committing — gap mornings are fast and the first lurch is noise. NoVo re-maps the levels on the reset open so you're trading the gapped structure, not yesterday's.