Interest rate reasons. Corporate Bond Index (abbreviated as Corporate Bond Index) is an index compiled by Shanghai Stock Exchange to reflect the overall trend and income of corporate bonds in China stock market. The rise of corporate bond index in government bond index is the reason of interest rate. The government bond index is a sample of all fixed-rate government bonds listed on the exchange, which is weighted according to the issuance of government bonds. Government bond index has basically formed a trinity index system of stocks, bonds and funds in China's securities market.