About this scanner

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This is an automated premarket gap scanner. Every weekday morning it checks a watchlist of stocks and surfaces the ones that have moved sharply away from their previous closing price — the kind of early movement that often signals news, earnings, or unusual interest in a stock before the regular trading day begins.

The goal is simple: instead of manually checking dozens of charts each morning, the scanner does one pass, applies a set of filters, and shows only the names worth a closer look.

What a "gap" is

A gap is the difference between where a stock closed yesterday and where it's trading now. If a stock closed at $10 and is now trading at $11.50, that's a +15% gap. Large gaps usually mean something happened — an earnings report, a product announcement, an analyst rating change, or broader market news.

How to read the dashboard

The top row shows a summary of the most recent scan:

Gappers found: How many stocks passed all the filters this run. Often zero outside of active morning hours — that's normal.
Top gap: The largest percentage move among the stocks found.
Universe scanned: How many stocks were checked in total. Only a few of these typically pass the filters.
Status: "Alerted" means results were sent to the alert channel; "quiet" means nothing passed the filters.

The table below lists each stock that passed, ranked by the size of its gap:

#: Rank — #1 is the biggest gap.
Ticker: The stock's symbol. A short note about the likely catalyst appears underneath when available.
Price: The current price.
Gap: How far the price has moved from yesterday's close, as a percentage.
Volume: How many shares have traded. Higher volume means the move is backed by real activity, not a single trade.

The filters

A stock only appears if it clears all of these, which screen out noise and untradeable names:

Minimum gap: The move has to be large enough to matter (currently 5% or more).
Minimum price: Very cheap stocks are excluded — their percentage moves are erratic.
Minimum volume: Enough shares must be trading that the move is real and the stock is liquid.

How often it runs

The scanner runs automatically on weekday mornings around the US market open and posts its results here and to a private alerts channel. You're always seeing the most recent run — the page refreshes its data each time you load it.

Important

This tool only reads and reports market data. It does not place trades, give financial advice, or predict which way a stock will go — a large gap is information, not a recommendation. A move can reverse just as fast as it appeared. Always do your own research, and never invest money you can't afford to lose. Past movement does not guarantee future results.

Data provided by Finnhub. This scanner is an independent tool and is not affiliated with any exchange, broker, or data provider. Nothing here is financial advice.