The UK Supreme Court on Wednesday overturned the conviction of Tom Hayes, a former UBS and Citigroup trader who became the first banker convicted worldwide of manipulating the London Interbank Offered Rate (LIBOR), a key index used to set interest rates on millions of loans and mortgages. Hayes was sentenced in 2015 to 14 years in prison—later reduced to 11—for conspiracy to defraud, and served five and a half years before being released on parole.