Central Huijin Investment Ltd., a state-owned investment company, increased its stake in China's four largest state-owned commercial banks, in a move to boost the flagging stock market.

The banks filed statements to the Shanghai Stock Exchange on December 16.

The Industrial and Commercial Bank of China revealed that Central Huijin had purchased 175 million A-shares in the bank by December 12, about 0.05 percent of its capital stock. Huijin's share in the bank is now 35.36 percent.

China Construction Bank stated Huijin had purchased 103 million A-shares of its bank by December 12, accounting for 0.04 percent of its capital stock, bringing Huijin's share in the bank up to 57.26 percent.

The Bank of China announced Huijin had bought 113 million of its A-shares, or 0.04 percent of its capital stock, making Huijin's share account for 67.75 percent.

The Agricultural Bank of China stated Huijin had purchased 179 million of its A-shares, or 0.06 percent of its capital stock. This brings Huijin's total share in the bank up to 40.28 percent.