Three of the biggest private equity firms in the US have held preliminary talks to sell a minority stake to China's Social Security Fund, the Financial Times reported. The US$65.1 billion fund talked to Carlyle, KKR and TPG over the summer, looking to buy up to 9.9% of one of the firms. However, the discussions have not progressed since then, probably because of the falling share price of Blackstone, another US private equity firm. The China Investment Corporation, the sovereign foreign exchange reserve fund, bought a minority stake in Blackstone earlier this year. The Social Security Fund has been allowed to invest abroad since May 1, 2006. It has said that it wants to expand its foreign investments.