Guy Hands's lawyers are poring over the New York court judgment that dismissed the private equity tycoon's claims that Citi had misled him over his £4.2bn purchase of EMI.
Mr Hands believed that Citi tricked his firm, Terra Firma, into paying at least £1bn over the odds for the music company in 2007. However, an eight-strong jury decided that David Wormsley, the chairman of Citi's British broking arm, had not conned his one-time friend.
The private equity baron has risked 70 per cent of his personal fortune in EMI, which is struggling despite an array of stars like Joss Stone and Snoop Dogg.
A source said that the lawyers would be "getting some kip" following the two-and-a-half week trial, which ended on Wednesday, but then they will go through the case "for quite some time" before deciding whether to appeal.