The Full form of SENSEX is Stock Exchange Sensitive Index. SENSEX is the oldest stock exchange in India which is also known as BSE (Bombay Stock Exchange). It is a free-float market-weighted stock market index of 30 financially sound and well-established companies listed on Bombay Stock Exchange. These companies are also known as Blue chip companies of India. The 30 component companies which are some of the most actively and largest traded stocks are representative of various organizational sectors of the Indian economy.

SENSEX uses free floating market capitalization method to reflect the position of companies in the stock market. Its calculation is simply based on the total number of tradable shares of a company at the time of calculation. It was published since 1st January 1986; the BSE SENSEX is considered as the pulse of the domestic stock markets in India. The base year of the SENSEX was taken as 1978–79, and the base value as 100 on 1st April 1979.

On 25 July 2001 BSE launched a dollar-linked version of the SENSEX, which is known as DOLLEX-30. The full market capitalization of SENSEX as of 7th February 2020, was about US$1 trillion (₹76,112.3149 billion), which is 37% of GDP while its free-float market capitalization was US$607 billion (₹43,272.7852 billion).