The Tech 100 Index (NDX) represents the performance of leading non-financial securities actively traded on the NASDAQ Stock Market. The index is calculated according to a capitalisation-weighted method. Started in 1985, the NASDAQ-100 includes both domestic and foreign securities of leading companies in a variety of industry sectors: IT, telecommunications, retail, biotechnology, media, etc. The NASDAQ-100 is often referred to as NDX. The index doesn't measure stocks of investment or financial institutions, and it is recalculated once a year.