Premarket Session
US equity trading before the 09:30 ET open — thin, volatile, and where gappers first show themselves.
What it means
US stocks trade before the official open (as early as 04:00 ET at most brokers). Liquidity is a fraction of regular hours: spreads are wide, quotes can freeze, and a few thousand shares can move a small-cap several percent.
Premarket is where scanners first spot the day's movers, but data quality varies sharply by broker and plan — some feeds don't carry premarket trades at all, and a frozen quote can masquerade as a real price.
Why traders care
- The day's biggest movers are usually visible before the bell.
- Premarket high/low often act as support and resistance after the open.
In a TraderWe strategy
if HhmmSs >= 93000 and ChangePct > 4:
Buy()Restrict entries to regular hours — a common guard for strategies built on regular-hours data.
Related terms
Educational content, not investment advice. Engine details describe how TraderWe computes this value; other platforms may define it differently.