Reading the heatmap

Every rectangle is a listed stock. Its size is the company's market cap; its colour is today's price move, green up and red down, deeper shades for bigger moves. One glance answers the question that takes a table forty rows to answer: where did the market's money actually go today?

A ₦30 stock can be a far bigger company than a ₦600 one; what sizes the block is price times shares outstanding. This is the heatmap quietly correcting the most common beginner mistake on the NGX: judging a stock by its price tag.

The ASI is weighted the same way the heatmap is drawn. When a giant like DANGCEM or Airtel Africa moves 3%, the index follows, whatever the other hundred-plus stocks did. A huge block turning deep red often is the day's index story by itself.

After 'is the market up?', ask 'how many stocks are up?'. An index gaining 0.8% with 25 advancers and 60 decliners means a few heavyweights carried it while the typical stock lost money. Broad green is conviction; narrow green is two companies having a good day.

The banking blocks moving together is rarely about any single bank: it is a policy rate decision, an FX move, or sector-wide news being priced. One bank moving alone while its peers sit still is company news. The pattern tells you where to go read.

The heatmap generates questions, not trades. A stock up 9% deserves two checks before any reaction: was the volume real (a move on thin volume reverses easily), and is there a filing behind it? Listed companies must disclose market-moving information to the NGX, so the disclosures feed is where rumours go to be confirmed or die.