The DAX 30, or DAX Index, is a German stock market index comprising the 30 biggest companies - by market capitalization and liquidity - trading on the Frankfurt Stock Exchange (FSE). The German stock index DAX 30 (GER30) was introduced under "DAX" on July, 1st in 1988 by the Frankfurt Stock Exchange. It consists of the 30 largest companies listed on the Frankfurt Stock Exchange based on the market capitalization and liquidity.