MDAX is a German stock market index which mainly tracks the performance of medium-sized companies.

It is a subset of the DAX index and includes the 60 companies with the highest market capitalization that follow the DAX thirty. The MDAX index is an important benchmark for investors who invest in the mid-cap market segment in Germany. The MDAX index is calculated in real-time and is based on total return (TR) which includes both price changes and dividend payments. The index is weighted based on free float market capitalization. This means that the stocks of companies that have a higher proportion of their shares traded in the market are given a higher weighting in the index. As of August 2021, the top five companies in the MDAX index by market capitalization are Siemens Healthineers, Zalando SE, Airbus SE, Takkt AG, and Qiagen NV. The MDAX index was introduced in 1996 by Deutsche Börse AG and includes companies from various sectors such as consumer goods, technology, finance, healthcare, and industrials. The MDAX index composition is changed regularly and is reviewed quarterly. The selection of companies for the index is based on criteria such as market capitalization, trading volume, and liquidity. Investors use the MDAX index to gauge the performance of the mid-cap market segment in Germany. Companies included in the MDAX index are typically growth-oriented, have established business models, and offer a higher potential for capital appreciation compared to smaller companies. The MDAX index is also used as a reference index to create financial products such as exchange-traded funds (ETFs), options, and futures. In summary, the MDAX index is a significant benchmark for investors in the mid-cap segment in Germany. It includes 60 companies with the highest market capitalization after the DAX thirty and is calculated in real-time based on free float market capitalization. The index is reviewed quarterly and offers investors a diversified exposure to the German mid-cap market segment.