Ian Billington, a LIBOR options trader at UBS Warburg in London, will take a similar position in the firm's Tokyo office next month to replace Keichi Tanaka, who left the firm last month. Billington said he is excited about the move because it will be a new challenge. In London Billington reports to Christine Morrissey, managing director of fixed income derivatives Europe. Billington will report to Todd Morakis, Asian head of LIBOR trading in Hong Kong. Morrissey and Morakis were traveling and could not be reached by press time.