The Sensex is an index of 30 major companies trading on the Bombay Stock Exchange (BSE) in India. It is a market capitalization weighted index that is considered the benchmark for the Indian stock market and reflects its overall performance and movements. The Sensex components represent large, well-established companies across major sectors. The value of the Sensex is calculated based on the total market value of the component stocks, adjusted for float. It is one of the oldest stock market indices in India, providing a long time series of data since 1978.