Market Capitalization: What Share Price Times Shares Outstanding Does and Doesn't Mean

Market capitalization (market cap) is the total value of a publicly traded company's outstanding common shares. The formula is simple: share price multiplied by the number of shares outstanding. A company with 4 million shares trading at $20 each has a market cap of $80 million. Market cap measures only the equity component of a company's capital structure. It is the standard way to rank companies and stock exchanges by size and to compare corporate scale against economic indicators. U.S. regulators (per FINRA) group companies into bands: mega-cap (at least $200 billion), large-cap ($10-200 billion), mid-cap ($2-10 billion), small-cap ($0.25-2 billion), and micro-cap (under $0.25 billion). What market cap is *not* is just as important. It is not the company's available cash. It is not the price a buyer would pay to acquire the entire company, and it ignores debt and leverage entirely. For that, analysts use enterprise value, which adds debt and preferred stock and subtracts cash to give a fuller picture of what controlling the whole business is worth. Market cap also overstates realizable value for anyone holding a large stake, because it values every share at the last marginal trade price even though only the free float (the subset of shares actively trading, usually less than total shares outstanding) is liquid. Attempting to sell a large position at once runs into market liquidity limits and drives the price down. The relationship between a paper market cap and the value of real assets is explored in Why Market Cap Can't Buy a Country: Paper Valuations vs. Physical Asset Value.