A British jury has found a former Citibank and UBS trader guilty of being the ringmaster in the manipulation of a key interest rate, the London Interbank Lending Rate, or Libor.

The jury on Monday found 35-year-old Tom Hayes, who specialized in products pegged to yen-denominated Libor, guilty of manipulating the rate from 2006 to 2010. He was charged with conspiring with other traders — but he says he was made a scapegoat for a common practice.

Libor is a key rate that banks use to borrow from each other. Revelations that it was rigged shook the markets because the rate affects what people pay when they take out loans, such as a car loan.

Hayes is the first to be convicted by a U.K. jury of Libor rigging.