BEIJING -- China's four major State-owned banks on Friday revealed the amount of A-shares that the investment arm of the country's sovereign wealth fund bought in them in an effort to boost market confidence.

In separate filings to the Shanghai Stock Exchange, the banks specified the purchases by Central Huijin Investment Ltd on Wednesday - 4.73 million shares in the Industrial and Commercial Bank of China, 5.73 million shares in the Agricultural Bank of China, 3.84 million shares in the Bank of China and 2.81 million shares in the China Construction Bank.

After the purchases, Central Huijin now has a 35.43-percent stake in the ICBC, owns 40.16 percent of the ABC, 67.65 percent of Bank of China and 57.15 percent of China Construction Bank, according to the filings.

The banks said Central Huijin will purchase more of their shares during the next six months.

Central Huijin's plan aims to shore up share prices of State-owned commercial banks and buoy the struggling market, analysts said.

The move has fueled speculation that more support measures will be unveiled for the market before the 18th National Congress of the Communist Party of China, scheduled for Nov 8.

China's major Shanghai index tumbled more than 15 percent from its peak this year over concerns of a slowdown in the world's second-largest economy.

Central Huijin was established in 2003 to hold the Chinese government's stakes in banks and insurance companies.