Once SPY gaps overnight, the day's defining question is whether it's a gap-and-go (the gap holds and price continues in the gap's direction) or a gap-fill (price retraces to close the gap back toward the prior close). The pre-market structure, volume, and the gap's cause give real — if imperfect — clues about which is more likely.
What favors a gap-and-go
Gaps tend to hold and run when they're backed by real conviction: a strong catalyst (a decisive CPI/NFP surprise, major earnings), heavy pre-market volume confirming participation, and price holding firmly at the gapped level rather than drifting back. A gap that opens strong and the opening range breaks in the gap's direction on volume is the classic gap-and-go — the market has repriced and means it.
What favors a gap-fill
Gaps tend to fill when they lack conviction: thin pre-market volume, no clear catalyst (a drift-driven gap), or price already sagging back toward the close before the bell. The prior close acts as a magnet — unearned gaps often retrace to it. A weak, low-volume gap that fails to hold its opening range is a prime fade-to-fill candidate.
A gap with a reason runs; a gap without one fills. Volume and catalyst are the tell — conviction holds the gap, and its absence hands it back.
Trading the decision
Read the inputs at the open — catalyst strength, pre-market volume, where price sits versus the gap and prior close — then let the opening range confirm. A held opening range in the gap direction says go; a failed one says fill. Don't force the call before the range resolves. NoVo maps the pre-market structure, prior close, and opening range live, so the gap-and-go/gap-fill read is drawn on real levels rather than a guess — and you trade the resolution, not the prediction.