The whole market on one board. Each tile is a company: its size is how big the company is, its colour is how it has moved today — green up, red down, and the stronger the shade the bigger the move.
- S&P 500 / QQQ
- Two boards. Switch between them at the top.
- Zoom and pan
- Ctrl + scroll, or the zoom buttons, to get closer; drag to move around.
- Load all symbols
- The board opens with the 75 largest names so it appears quickly. This loads the rest.
- ⟳ Update data
- Throws away the stored board and pulls fresh quotes. Next to it, a timestamp shows when the data was captured — see chapter 20 for why boards are shared.
About the constituent list The companies on each board are a hand-picked list of large caps. It is not a licensed S&P 500 or NASDAQ-100 membership list, because no data provider on the plans this app uses sells one. So the board is representative rather than exact, and the page says so next to the legend.
The colour stops at 3%. The scale runs from −3% to +3% and everything past that is the same darkest shade, so a company down 12% looks exactly like one down 3%. This is worth knowing before you read a board on a bad day. The alternative is worse: scaling the colour to the worst mover means one company collapsing 40% washes the entire board pale and the other four hundred become unreadable. Hover a tile — or open it — for the actual figure.
Size and colour are answering different questions. A small red tile on a green board is one company having a bad morning. A large red tile is a bad morning for everybody holding an index fund, because a big enough company moves the index by itself. Reading the two together is the whole point of a treemap: a list sorted by percentage change puts a tiny company at the top and tells you nothing about whether it mattered.
Clicking any tile opens that company's chart, which is usually the next thing you want — the board tells you where to look, not why.