Industry bods and CNBC commentators call it "market cap", perhaps because it sounds better or they don't have time to finish the word "capitalisation". Market capitalisation is the total market value of a company's outstanding shares. Companies are ranked from large cap (the FTSE 100 or S&P 500) to small cap (FTSE Small Cap index). Definitions vary as markets move. Anything smaller than £500m (a small amount in the age of big numbers) is normally regarded as small cap.