Market capitalization (market cap) is the total dollar value of all outstanding units of an asset: price × circulating supply. For stocks, it is share price times shares outstanding. For crypto, it is token price times circulating supply. Market cap is the basic measure of an asset's economic size and is used to compare assets, weight indexes, and define investment universes (large-cap vs mid-cap vs small-cap).
Two related metrics matter alongside basic market cap: fully diluted valuation (FDV), which uses total supply (including unreleased tokens or unvested shares), and free-float market cap, which uses only the publicly tradeable supply. The three can differ wildly, especially for early-stage crypto with large unreleased token allocations.
Caveats: market cap is a flawed measure of "value". You cannot actually sell all the supply at the current price; trying to do so would crash the price. For thinly-traded assets, market cap massively overstates the realized value of the float.
Market cap is the single most cited number in finance. It defines index weights (S&P 500 is market-cap weighted), determines fund eligibility, and orders crypto leaderboards. Understanding the difference between market cap, FDV, and float prevents being misled about what a number actually means.
The crypto-movers endpoint sorts by market cap by default. The premium macro endpoint covers the same concept for equities.