AMGN’s market cap is 143.19 Bil. Market capitalization is calculated by taking a company’s share price and multiplying it by the total number of shares. It’s often used to measure a company’s size. In the Morningstar Style Box, large-cap names account for the largest 70% of U.S. stocks, mid-cap names account for the largest 70–90%, and small-cap names are the remaining 10% of companies. Learn more about market capitalization.