The composite indices of the Shanghai and Shenzhen stock exchanges rose by more than 8% Wednesday on news that China's central bank said it has no plans to raise interest rates, state media reported. The Shenzhen stock exchange closed at 2,936.57 points, up 8.38%, its biggest one-day jump since June 24, 2001. Analysts said the market was due for a strong rebound after a freefall of share prices in the past seven weeks; news that regulators are allowing listed firms to buy back their shares also gave the market a boost.