Methodology

GainersLosers tracks a curated set of roughly 1,000 US-listed stocks — liquid names followed by the PreMarketPrice pipeline. It is deliberately not the whole market: sub-$5 or thinly traded names are filtered out of every ranking (a +400% move on a $0.04 stock is noise, not signal).

% move — the session’s close-to-close percentage change (during the live session: last price vs previous close).

σ score (z-score) — how unusual the move is for that specific stock — the day’s move expressed in standard deviations of its own ~20-day daily-return distribution. 2σ ≈ a once-a-month move, 5σ ≈ a once-a-year event. It measures surprise, not company quality.

× volume (RVOL) — today’s volume relative to the stock’s recent average volume. 3× means three times the normal interest.

vs sector — the stock’s move minus its sector’s median move — the part of the move the sector can’t explain.

$ move — the change in the stock’s total market value in US dollars (shares × price change), not a per-share price change.

% move — stocks with the largest absolute daily percentage change.

$ move — stocks with the largest absolute change in market value in USD. This view deliberately widens the universe — a mega-cap moving 1% can shift more dollars than a small-cap moving 50%, so names above $1B market-cap change are included even without an unusual % move.

σ score — stocks ranked by |z-score| — statistically abnormal moves regardless of direction.

Weekly — the compounded close-to-close return over the last 5 completed trading sessions. A partial current session never anchors the period.

Each mover is checked against that day’s news and filings pipeline. The badge shows the classified catalyst type (earnings, M&A, product, analyst, guidance…). Its color encodes honesty, not decoration:

• Dark badge — a confirmed catalyst with supporting evidence.
• Amber badge — a plausible but weak or unconfirmed signal.
• Gray badge — context only (sector-wide or market-wide move), not a company-specific cause.
• No row at all — no catalyst found; the site never fills the gap with a generic explanation.

Prices come from Polygon (≈15-minute delayed on the current plan) and news from Finnhub, via the PreMarketPrice data pipeline, refreshed continuously during market hours. The header chip always shows which session the numbers describe — a stale date reads “closed”.

A ranking board is a discovery surface, not an investment opinion. For fundamentals, valuation history and full analysis, every card links to the company’s page on PreMarketPrice. Nothing here is investment advice.