The movers Z-score expresses today's move in standard deviations of the stock's own history — a 2% move is normal for a volatile name but extraordinary for a sleepy one. Z-score filters the noise: green tiles are moving abnormally for them. This heatmap colors US stocks by Z-score, sized by market cap and grouped by sector.
Greener tiles are positive outliers, redder tiles negative outliers — both are statistically unusual, not just big movers.
Beyond ±2 is a ~95th-percentile move for that stock; beyond ±3 is rare. Unlike raw percent, it respects each stock's own volatility profile.
A 5% move on a boring utility is more informative than 5% on a biotech — the first is a signal, the second is Tuesday. Z-score normalizes for that.
Earnings surprises, guidance changes, analyst actions, sector shocks or company news — a genuine outlier move almost always has a catalyst behind it.
Heatmap data updates through the trading session. Fundamentals come from Finnhub and SEC filings; scores are simplified heuristics for screening — not investment advice.