Tools · Live Market Map
S&P 500 Heatmap
Every S&P 500 company as one block: sized by market cap, grouped by GICS sector, colored by today’s move. Hover or tap a block for the price, change and market cap behind it.
After-hours change vs today's 4:00pm ET close · Updated 4:04 PM EDT
How Is the Stock Market Doing Today?
The short answer: 171 of 503 S&P 500 stocks are up and 155 are down in after-hours trading as of 4:04 PM EDT, with Information Technology the strongest sector by cap-weighted move and Consumer Staples the weakest. The map above shows every one of those moves at once, and the session toggle switches the same view between regular-hours, pre-market and after-hours trading.
How to Read a Market Heatmap
A market heatmap compresses an entire index into one picture. Each rectangle is a company, its area is proportional to market capitalization, and its color is the day's percentage move: green for up, red for down, with intensity capped at a 3% move. Because the blocks are grouped into sectors, the first glance tells you where the day is happening: a sea of red with one green sector is a rotation, uniform color is a macro day, and a single deep-colored mega-cap block is a stock story big enough to move the whole index.
Size matters more than color. A 1% move in the largest technology block moves the index more than a 10% move in the smallest utility, which is exactly what the areas are telling you. That is also why cap-weighted days can feel wrong: most tiles can be green while the index falls, if the few giant tiles are red.
The session toggle switches the same map between the regular session, pre-market and after-hours. Extended-session prints are thinner and moves there routinely fade or reverse at the open, so treat the pre-market map as a watchlist, not a verdict. For what is scheduled to move these stocks next, our earnings calendar pairs naturally with this page.
S&P 500 Heatmap FAQ
- What do the colors on this heatmap mean?
- Each block is colored by that stock’s percentage move for the selected session: shades of green for gains, shades of red for losses, gray for unchanged or no data. Color intensity is capped at a 3% move in either direction, so anything at the deepest green or red has moved at least 3%. Every block also shows the signed percentage when it is large enough, and the popup always carries the exact figure.
- What decides the size of each block?
- Block area is proportional to the company’s market capitalization within the S&P 500, so the biggest companies take the most space, and blocks are grouped into GICS sectors sized the same way. Membership and market caps were last refreshed on 2026-08-04.
- How often do the prices update?
- Quotes refresh roughly every minute while you keep the page open during market hours, and the page itself is re-rendered with fresh prices about once a minute, so the colors you land on are already current. When the market is closed the map shows the last completed session.
- Does this heatmap show pre-market and after-hours trading?
- Yes. Use the Regular / Pre-market / After-hours toggle above the map. In pre-market mode colors show each stock’s pre-market change versus yesterday’s close; in after-hours mode they show the move since the 4:00pm ET close. Stocks that have not traded in the extended session show gray.
- Which companies are included in the S&P 500 heatmap?
- All 503 S&P 500 constituents in our current snapshot, including dual-listed share classes where the index holds both (for example Alphabet’s GOOGL and GOOG). Membership is re-verified weekly. The Nasdaq 100 heatmap is one tab over.