Goldman Sachshas told its board that an internal investigation found little substance to allegations made by Greg Smith, the disaffected employee who claimed the bank has a “toxic environment” where bankers refer to clients as “muppets”.

The review found that weeks before his public resignation – when he railed against Goldman staff who “care only about making money” – Mr Smith, who worked in derivatives sales, complained about his bonus and said he deserved to be paid more than $1m, according to people familiar with the matter.

Mr Smith’s book, entitled Why I Left Goldman Sachs, is set for publication on October 22 and the bank is braced for more allegations. But the board was told by bank officials that they could not substantiate claims made on March 14 in an open resignation letter published as an article in The New York Times. They recommended no further action be taken.