Definition
What is a gap scanner?
A gap scanner compares a current session price with an explicit reference, commonly the prior regular-session close, and filters symbols by the size and direction of that difference. The reference, timestamp, and active session determine what the percentage means.
Who it is for
Built for active traders who verify the evidence.
TraderBase gap workflows are for active traders building a provisional premarket or opening watchlist and checking whether price movement is accompanied by sufficient volume, liquidity, and verifiable context.
How it works
From changing data to a focused review.
- 1Choose the premarket or applicable session and the correct prior-close reference.
- 2Apply supported price, absolute-gap, volume, relative-volume, float, market-cap, exchange, and news filters.
- 3Review current quote timing, spread, premarket high and low, and available catalyst evidence.
- 4Re-evaluate the candidate after the opening session changes liquidity and price structure.
Capabilities
The information connected to this workflow.
Explicit gap reference
Keep the prior close, current session, and price timestamp visible rather than mixing incompatible fields.
Participation filters
Pair percentage movement with premarket volume, dollar volume, and a valid relative-volume baseline when available.
Tradability checks
Review spread, float, liquidity, nearby levels, offerings, filings, and halt risk before promoting a ticker.
Opening transition
Treat premarket ranking as provisional and monitor supported opening, high-of-day, VWAP, or failure events.
TraderBase approach
What makes TraderBase different?
TraderBase presents a gap as a calculation with a reference and time—not as a trade signal. Missing float or catalyst data remains unknown, and a headline is shown as context rather than proof that the move will persist.
Common questions
Gap scanner FAQ
How is a premarket gap usually calculated?
It is commonly the percentage difference between the current premarket price and the prior regular-session close. A scanner should identify the exact fields and timestamps it uses.
What is a good minimum gap percentage?
There is no universal threshold. A useful boundary depends on the strategy, price universe, liquidity needs, data coverage, and risk limits and should be evaluated with volume and spread.
Does a gapping stock need news?
Not every gap has a supported headline, and provider coverage can be incomplete. News status is context; it should not be treated as proof that no other catalyst exists.