Sector Heat Map

What you are looking at

• One rectangle = one company. Companies are grouped inside their industry, and industries inside their sector (the classification comes from the NASDAQ listing directory). Rectangle area is the company's market value, so the map is dominated by the companies that actually dominate the market.
• Color = the measure you picked. Green is good, red is bad, dark gray is neutral or "no data". For valuation measures (price / earnings and friends) green means cheap and red means expensive, since a low price tag is the good end.
• Sector and industry colors are weighted averages. Each group is colored by the market-value-weighted average of its members, after clipping each company at the color scale's limits — so one wild +4,000% mover cannot drag a whole sector green on its own. Companies with no data for the measure are left out of the average.
• Ranked tables below the map show everything as text. Three sortable tables — sectors, industries, companies — with every measure as a column, colored on the same scale as the map (the highlighted column is the current sort). Click a column header to rank by it, click again to flip best/worst. The column you sort by jumps to sit right after Market value (under a "Sorted by" band) so it stays in view; drag any column header to rearrange the columns to your taste — the arrangement is remembered on this browser, applies to all three tables, and a "Reset column order" button appears whenever you have a custom arrangement (dragging the sorted column parks it where you drop it). Sector and industry rows combine their members as a market-value-weighted average or a plain median (toggle above the tables — a big gap between the two means one giant is skewing the group). The first column stays pinned while you scroll sideways, and company tickers link to the screener detail.

Where the numbers come from

• Price changes — measured from official daily closing prices, with "now" being the live Ada / Alpaca price (refreshed every 5 minutes). "1 day" means the move since the previous official close. "Year to date" measures from the final close of last year.
• Growth, margins and valuation — identical to the screener's columns, computed from each company's SEC filings: "12-month" always means the four most recently reported quarters added together, and growth compares against the same period one year earlier. The screener page's guide has worked examples of each computation.
• Example — if Semiconductors shows +1.9% on "Price change — 1 day": take every semiconductor company on the map, clip each one's 1-day change at ±5%, weight by market value, and average.
• What is excluded — companies whose newest filing is stale (over ~7 months old, or ~14 for annual-only foreign filers) are dropped entirely. Foreign filers whose filing currency we cannot confirm keep their price-change colors but show no valuation ratios (a dollar price divided by yen profits is meaningless).
• One caution on banks — for the Finance sector, "revenue" is interest income under different accounting rules, so revenue growth and margin colors are unreliable there (most banks simply show gray). Profit and price-change colors are still valid for them.