A market capitalization-weighted index of 40 of the largest companies that trade on the Hong Kong Exchange. The Hang Seng Index is maintained by a subsidiary of Hang Seng Bank, and has been published since 1969. The index aims to capture the leadership of the Hong Kong exchange, and covers approximately 65% of its total market capitalization. The Hang Seng members are also classified into one of four sub-indexes based on the main lines of business including commerce and industry, finance, utilities and properties.