Every morning, from his desk by the bathroom at the far end of Royal Bank of Scotland Group Plc's trading floor overlooking London's Liverpool Street station, Paul White punched a series of numbers into his computer.

White, who joined RBS in 1984, was one of the employees responsible for the firm's submissions to the London interbank offered rate, or Libor, the global benchmark for more than $300 trillion of contracts, from mortgages and student loans to interest-rate swaps. Behind him sat Neil Danziger, a derivatives trader at the bank since 2002. On the morning of March 27, 2008, Tan Chi Min, Danziger's boss in Tokyo, told him to make sure the next day's submission in yen would increase.

“We need to bump it way up high, highest among all if possible,” Tan, known by colleagues as “Jimmy,” wrote in an instant message to Danziger, according to a transcript made public by a Singapore court and reviewed by Bloomberg before being sealed by a judge at RBS's request.