Gap Up

A gap up occurs when a stock's opening price is significantly higher than its previous day's closing price, with no trades occurring at the prices in between. On a price chart, this creates a visible gap — a price range where no trading took place. Gap ups are almost always caused by catalyst events that occurred after the market closed or before it opened: earnings reports, FDA decisions, M&A announcements, or significant analyst actions.

Types of Gap Ups

Common gap. A relatively small gap (1–3%) that occurs in normal market fluctuation and typically fills quickly as the stock reverts to its previous trading range. These gaps have limited trading significance.

Breakaway gap. A larger gap (5–15%+) driven by a significant catalyst that changes the fundamental trading range of the stock. Breakaway gaps often mark the beginning of a sustained trend and frequently do not fill quickly — the catalyst event genuinely changed the stock's value.

Exhaustion gap. A gap that occurs at the end of a sustained trend, often representing the final burst of momentum before a reversal. These are harder to identify in real time and require broader trend context.

Premarket Gap Ups as Catalyst Indicators

Premarket gap ups are closely monitored because they represent the first post-catalyst price discovery before the regular market opens. A stock showing a 20% premarket gap up following an after-hours earnings beat is pricing in the earnings surprise in real time. The size of the premarket gap provides a market consensus estimate of the catalyst's value that continues to be refined through the opening bell. TradeAI News monitors premarket movers and surfaces significant premarket gap ups through the Premarket Movers scanner.