Singapore’s sovereign wealth fund has pocketed a $1.6bn profit after selling half of the 9 per cent stake in Citigroup it acquired during this year’s US-government led refinancing of the troubled bank.

In an unexpected announcement on Tuesday, the Government of Singapore Investment Corporation said that the sale followed the conversion, on September 11, of its $6.8bn of convertible preferred stock for Citigroup common stock at $3.25 a share.