Market Index
Also called: stock index, index, equity index
A market index is a rules-based basket of securities used to represent a market's performance. Most are capitalisation-weighted, so a company's influence scales with its size — which is why a handful of mega-caps can drive an entire index. Alternatives weight by price (the Dow) or equally. An index is a measurement, not an investment: you access it through a fund that tracks it, and the tracking difference plus fees is what separates the two.
Where this is taught
Definitions are the trailer. These free levels turn Market Index into something you play — one bite-size lesson, with worked examples, a quiz and XP.