A stock market heatmap compresses an entire index into one picture: every company is a box, the box’s size reflects its market value, and its colour shows today’s price move. Green means up, red means down, and the deeper the shade, the bigger the move. Below are live maps for the S&P 500 and the FTSE 100, the current sector weights behind them, and a short guide to reading the picture like an analyst. For the full dashboard, head back to live markets.
S&P 500 heatmap (live)
FTSE 100 heatmap (live)
How to read a heatmap
Three things matter: size, colour and clustering. Size is market value, so the biggest boxes move the index most. A 2 per cent fall in the largest technology names outweighs a rally in everything else, which is how an index can close red on a day when most of its members rose. Colour is the day’s return. A sea of pale colour means a quiet, mixed session; uniform deep red or green means a macro move, where a rate decision, an inflation print or a geopolitical shock is repricing everything at once. Clustering is the tell: when one sector block is deep red while the rest of the map is calm, the story is sector-specific, such as an earnings miss cascading through semiconductors, or an oil move hitting energy. When defensive sectors like utilities and consumer staples are green while technology and discretionary are red, that is a risk-off rotation rather than simple selling.
The switch in the map’s top bar also lets you view performance over a week, a month or a year rather than a single day, which is often more informative than the daily noise. For the mechanics behind the moves themselves, see why share prices move and stock market indices explained.
S&P 500 sector weights
The heatmap’s proportions reflect these weights. Information technology alone is now more than a third of the index, which is why the AI trade dominates daily index moves. Weights below are as of late July 2026, based on the holdings of the largest S&P 500 tracking funds, and shift gradually with prices.
| GICS sector | Approx. weight | Largest names |
|---|---|---|
| Information Technology | 37.5% | Nvidia, Microsoft, Apple, Broadcom |
| Financials | 12.4% | Berkshire Hathaway, JPMorgan, Visa |
| Communication Services | 9.3% | Alphabet, Meta, Netflix |
| Health Care | 9.1% | Eli Lilly, Johnson & Johnson, AbbVie |
| Industrials | 8.9% | GE Aerospace, Caterpillar, RTX |
| Consumer Discretionary | 8.8% | Amazon, Tesla, Home Depot |
| Consumer Staples | 4.6% | Costco, Walmart, Procter & Gamble |
| Energy | 3.4% | ExxonMobil, Chevron, ConocoPhillips |
| Utilities | 2.3% | NextEra Energy, Constellation Energy, Southern Co |
| Real Estate | 1.9% | Prologis, American Tower, Equinix |
| Materials | 1.8% | Linde, Sherwin-Williams, Freeport-McMoRan |
Two practical implications follow. First, concentration: the top ten companies account for well over a third of the index, so “the market” increasingly means a handful of technology names, a theme running through our ongoing coverage of the AI infrastructure supercycle. Second, contrast with London: the FTSE 100 leans towards financials, energy, miners and consumer staples rather than technology, which is why the two indices often move very differently on the same news.
Frequently asked questions
Why are some boxes so much bigger than others?
The maps here weight each company by market value, mirroring how the index itself is built. A $4 trillion company simply matters more to the index than a $20 billion one, and the map makes that visible at a glance.
Can the index fall when most stocks rise?
Yes, and it happens regularly in today’s concentrated market. If the few largest names fall while hundreds of smaller members rise, the weighted index still drops. Watching breadth, meaning how many stocks are green versus red, tells you whether a move is broad-based or driven by a handful of giants.
How often do sector weights change?
Continuously with prices, and step-wise when the index committee adds or removes companies or reclassifies a sector. The broad shape moves slowly: technology’s rise from a quarter to more than a third of the index took several years of AI-driven outperformance.
Data provided by TradingView. Sector weights are approximate and drift with prices. Nothing on this page is investment advice.