Research
What happens after a huge gap up?
TheDesperateTrader.com· Opened at least 20% above the prior close
An enormous overnight gap up of 20% or more - a news or halt-reopen move, and a coin flip from the open. Over 3k days, it fades from the open on average - and 19% of the time the gap filled.
Gap up 20%+
Opened at least 20% above the prior close
Fades the gapdays3k
◀ closed red from openopenclosed green ▶
−2%dashed = market baseline+2%
Avg gap
+26.90%
Avg open→close
−0.29%
Closed green
41.6%
Filled the gap18.6%
Share that traded back down to the prior close at some point during the day.
What this means rules-based, no AI guesswork
- On average it gives back the pop: the typical day closed −0.29% from its open versus −0.02% for a normal day.
- 19% of these gap-ups traded back down to the prior close at some point - the gap "filled".
- Fewer than half (42%) actually closed green from the open, so buying the open was a coin flip at best.
Want to catch these gaps live?
The base rate is the honest context. Our real-time scanners are where you find these names as they gap.
Base rates measured over our own daily history (2024-12-03 to 2026-09-16), tradeable-liquidity names only, split-scale moves excluded. Gap fill means the price touched the prior close intraday, not a trade you would keep. This is research, not investment advice.