Market Capitalization

In Depth

Market capitalization — commonly shortened to "market cap" — is the most widely used measure of a company's size in the public equity markets. It is calculated by multiplying the current share price by the total number of shares outstanding. Companies are typically classified into size categories: mega-cap (above $200 billion), large-cap ($10-200 billion), mid-cap ($2-10 billion), small-cap ($250 million to $2 billion), and micro-cap (below $250 million). Market cap determines a company's weight in capitalization-weighted indices like the S&P 500, which means that the largest companies have the most influence on index performance. It also affects institutional investor mandates, as many funds are restricted to investing only in companies above a certain market cap threshold. Market cap differs from enterprise value, which adds debt and subtracts cash to represent the total cost of acquiring a business. For executives, market capitalization affects stock-based compensation, acquisition currency, index inclusion eligibility, analyst coverage, and institutional investor interest. Changes in market cap can trigger index rebalancing events that create significant trading volume.