US private equity giant Carlyle Group has agreed to sell a 7.5 per cent non-voting stake to Mubadala Development Company, an Abu Dhabi government-owned investor, for $1.35 billion in a deal that values Carlyle at $20 billion. The private equity giant denied the sale was a prelude to an IPO. In 2000, when California Public Employees' Retirement System took a 5.5 per cent stake for $175 million, the Washington-based firm was valued at $3.2 billion. Carlyle had less than $10 billion in assets under management at that time. Mubadala also agreed to commit $500 million to a Carlyle investment fund. Carlyle is the latest alternative asset manager to sell a stake to an Asian or Middle Eastern investor. In May, an investment arm of the Chinese government paid $3 billion for a 9.7 per cent non-voting stake in Blackstone, ahead of the firm's initial public offering.