The banks told its board of directors that weeks before his public resignation, Greg Smith complained about his bonus and said he deserved to be paid more than $1m, according to the FT.

Goldmans began the investigation in March after Smith, who worked in derivative sales, used an open resignation letter published in the New York Times to attack the bank.

Smith, who was based in London for the final years of his career at Goldmans, said staff described clients as “muppets” and “care only about making money.”

Smith argued Goldmans was no longer acting in the interests of clients, saying: “It makes me ill how callously people talk about ripping their clients off.”

Goldmans responded by launching an investigation nicknamed the ‘muppet hunt’, in which it interviewed dozens of staff and sifted through millions of emails, finding about 4,000 ‘muppet’ references. The bank said 99% of those referred to the Muppets film released last year.

One email sent to Smith from a salesperson said: “The muppets don’t understand they can trade the futures through a block with other liquidity providers.”

Goldman executives said while the language was disparaging, it did not mean the salesperson was trying to take advantage of clients, but rather help them understand a trade.

Smith’s book, Why I left Goldman Sachs, is due for publication later this month, but bank officials have told the board they could not find enough evidence surrounding the claims and so no further action is needed.