Stock Market Heatmap

How to read the heatmap

Every tile is one company. Tile size follows its approximate weight in the index, so the mega caps dominate the picture the way they dominate the index — except on the Dow 30, which is price-weighted, where size follows share price instead. Tile color is the move over the window you pick, from a single session out to a full year, and the color scale widens with the window: a 3% day saturates a tile, a 3% year barely tints it.

Tiles are grouped into sector blocks, and the strip along the top pairs each sector with the SPDR fund that tracks it. The big number is the cap-weighted move of that sector's constituents on the map; the smaller one underneath is the fund's own return. They are two different numbers and often not close ones, because the funds cap their largest holdings and rebalance quarterly. Prices are real time and the map refreshes itself every 60 seconds.

Five ways to actually use it

1. 1Separate the day from the trend. Read 1D for today's tape, then click 1M and 1Y and watch what changes. A red tile inside a green year is a pullback in an uptrend; a red tile inside a red year is a downtrend adding another day.
2. 2Ask whether it is macro or news. When a whole index shades the same direction, that is the market moving and individual tiles say little. When the map is patchy — one deep-green tile in a flat sector — that is a stock-specific story worth opening.
3. 3Check breadth against the fund. Compare a sector's cap-weighted number with its ETF underneath. A sector well ahead of its fund is being carried by a few giant names; a sector in line with the fund is moving broadly.
4. 4Drill in, then back out. Click a sector chip to give one sector the whole canvas — small names that were unreadable slivers become full tiles, and the barometers on the right re-scale to that slice. Click All to zoom back out.
5. 5Change the index to change the question. S&P 500 is the broad market, Nasdaq 100 is large-cap growth with no financials or real estate, and Dow 30 is 30 names weighted by share price. The same session can look completely different across the three, and that difference is the signal.

Click any tile or sector card to open that symbol's free chart. Membership wires the same map to Premium Charting and adds premium alerts. Educational analysis, not financial advice.

How to use the 9-box

The heatmap tells you which companies moved. The 9-box in the rail beside it tells you what kind of company moved. It cuts the same names two ways — company size down the rows, Small at the top through Mid to Large at the bottom, and valuation style across the columns, Value to Blend to Growth — and colors each of the nine cells by the cap-weighted change of the names that land in it.

It always describes exactly the map next to it: pick the Nasdaq 100, filter to Energy, switch to a 3-month window, and the grid follows. Its color scale is its own, fitted to the spread across the nine cells rather than the treemap's fixed ramp, because a size band moving 0.4% is a real day and would otherwise come out gray. Hover a cell for how many names it holds and which ones lead it.

Underneath the grid, Top Performing Stocks names the strongest of the nine cells and lists the five best performers inside it over the same window. It moves with the grid, so it always answers the question the grid raises: leadership has rotated to, say, Small Growth — which small growth names actually carried it? On a session where not one cell is up, it flips to Worst Performing Stocks in the most negative cell instead, because on a day with no leadership the useful question is where the damage is deepest.

What the patterns mean

• A green column. One style is leading regardless of size. A green Growth column with a red Value column is the classic risk-on day; the reverse usually shows up when rates or energy are driving the tape.
• A green row. One size band is leading regardless of style. Small green with Large red means breadth is better than the index level suggests — the index is being held back by its biggest members, not by the market.
• A diagonal. Money is rotating, not just rising or falling. Large Growth green against Small Value red, or the mirror image, is the single most useful thing this panel shows.
• Everything one color. Nothing is rotating. It is a macro session, and the individual tiles on the map are mostly beta rather than news.

Size uses cumulative market cap with 70% / 90% cuts. Style is our own valuation composite — price/book, P/E, price/sales and yield — not a Morningstar style box. Cells with no names in the current view are drawn as dashed outlines. Educational analysis, not financial advice.