SectorsUpdated daily after close · as of 2026-07-21
Market Heatmap: Top 100 US Stocks & Thematic Sector Treemaps
Box size encodes market cap (shares × latest close, recomputed daily); color encodes return over the selected window, clamped at ±5%. Switch to the sector view for curated thematic maps — AI, cloud, cybersecurity, defense, EVs, quantum, and more.
Today's reading
As of market close on July 21, 2026, 59 of the top 100 US stocks by market cap closed higher (59% green), with 6 of the 10 largest names up. Best performer: SNDK +14.27%; worst: SAP -2.53%. Box sizes reflect live market caps (shares × latest close); the largest is NVDA.
Sources, methodology & freshnessLast updated 2026-07-21 · Open ↓Close ↑
Source
Daily closes for ~5,600 US equities + Polygon shares-outstanding reference
Methodology
Treemap: area = shares × latest close; color = 1d/7d/30d return, clamped ±5%
Updates
Daily after market close (~1:30 PM PT)Last: 2026-07-21
Maintained & reviewed by Yuriy Matso — methodology shown on the page.
-5%
+5%
01
About this map
thetrading.tools PRO
Talk to this data with your AI
PRO is an MCP server that plugs Claude, ChatGPT, Cursor or any AI agent straight into everything on this site — the live market scores, ~90 economic indicators with full histories, and every signal study. Ask a market question; your AI answers from our data, dated and sourced.
Get PRO — $39/mo
Cancel anytime
How Market Heatmap Works
- 1Size every box by live market capMarket cap is recomputed daily as shares outstanding × the latest close from our own price database, so box sizes track the actual market rather than a stale snapshot. The Top 100 view ranks the entire cap universe each evening.
- 2Color every box by returnCell color encodes the selected return window — daily, weekly (7 calendar days), or monthly (30 calendar days) — on a red-to-green scale clamped at ±5%. Deep green/red means a move of 5% or more.
- 3Slice by theme, not just sizeThe By Sector view renders a separate treemap per curated theme — AI & Machine Learning, Cloud & SaaS, Cybersecurity, Defense, EVs, Energy Storage, Fintech, Quantum Computing, Clean Energy, and Semiconductors — so you can see rotation within the themes that actually drive flows.
Who Uses Market Heatmap
Morning Scanners
One glance answers "what kind of day was it?" — broad green, broad red, or a split tape where mega-caps masked weakness underneath.
Theme Traders
The sector maps show rotation between themes: quantum red while defense is green is a real risk-appetite signal you can't see in index charts.
Swing Traders
Switch to the weekly/monthly windows to spot leaders holding gains while the index chops — relative strength at a glance.
Pro Tips
01
Compare the daily and monthly views back-to-back
A stock red today but deep green on the month is a pullback in an uptrend; green today but red on the month is a bounce in a downtrend. The pair of views separates noise from trend in two clicks.
02
Watch the biggest boxes for index direction
The top ~10 boxes are most of the S&P 500's weight. When they disagree with the rest of the map, the cap-weighted index is hiding the real breadth — cross-check the A-D line.
03
Use sector maps for pair ideas
Within a theme, the outlier (one red box in a green sector) is either tomorrow's laggard catch-up trade or the name with a real problem — worth the 30 seconds to find out which.
Common Issues & Solutions
A stock I expected is missing from Top 100▾
The universe is built from our cap database (Polygon shares-outstanding snapshot × live prices). Recent IPOs or symbols missing from that snapshot won't rank until the next shares refresh. GOOGL is deliberately excluded as a duplicate of GOOG.
Sector boxes look too similar in size▾
A few thematic names lack shares-outstanding data; they're sized with a price-based placeholder so they stay visible. Treat sizes in sector view as approximate for the smallest names.
Returns look small on a big news day▾
Data is end-of-day. Intraday moves show up after the next close — this is a daily-close instrument, not a live tape.
Frequently Asked Questions
What is a market heatmap?▾
A treemap visualization of the stock market: each rectangle is one stock, its area proportional to market capitalization and its color encoding return over a chosen window. It compresses hundreds of price moves into one picture — the fastest way to see whether a move was broad or narrow, and which themes led.
How are the boxes sized?▾
By market capitalization, recomputed daily as shares outstanding × the latest closing price from our ~5,600-symbol price database. Shares-outstanding data comes from a Polygon reference snapshot (it changes slowly); prices update every close.
What do the colors mean?▾
Return over the selected window — daily, weekly (7 calendar days), or monthly (30 calendar days) — on a red-to-green gradient clamped at ±5%. Gray cells lack return data for that window.
What are the sector maps?▾
Curated thematic groups (AI & Machine Learning, Cloud & SaaS, Cybersecurity, Defense, EVs & EV Infrastructure, Energy Storage, Fintech, Quantum Computing, Clean Energy, Semiconductors) rather than formal GICS sectors. Themes are where rotation actually happens; the GICS view lives on our Sector Health dashboard.
How often does it update?▾
After every market close, alongside the rest of the daily pipeline. The timestamp under the title shows the data's as-of close.
Explore Other Tools
Last updated: 2026-07-21