Simplify the following text for a Grade 6 native English-speaking person.
Original: The DAX ( Deutscher Aktien IndeX , formerly Deutscher Aktien-Index ( German stock index ) ) is a blue chip stock market index consisting of the 30 major German companies trading on the Frankfurt Stock Exchange .
Simplified: In German DAX stands for Deutscher Aktien Index ( in English : German stock index ) . 30 companies are in this exchange .