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. Taobiz explains Hang Seng Index - HSI The Hang Seng is the most widely quoted barometer for the Hong Kong economy. Because of Hong Kong's status as a special administrative region of China, there are close ties between the two economies and many Chinese companies listed on the Hong Kong Exchange.