Dax index has a whole group of indices, that includes MDAX, SDAX and TecDax.
1. MDAX is index of 50 companies according to the first thirty in size. They called medium-cap companies.
2. SDAX is an indicator of German small-caps, following MDAX in the overall rankings. There are 50 companies that form this index.
3. TecDax is an index which represents the high-tech sector with 30 largest German companies.