A top executive at brokerage firm ICAP PLC knew of an arrangement with UBS AG that U.S. and British regulators allege was part of a scheme to rig benchmark interest rates, the Wall Street Journal reported today. The ICAP executive, David Casterton, was included on emails between ICAP and UBS officials in 2007 as they negotiated a deal that regulators say was designed to compensate ICAP brokers for helping UBS traders manipulate the London interbank offered rate (Libor), and Casterton ultimately signed off on the arrangement. British regulators have described the arrangement, which they say involved UBS making quarterly payments to ICAP allegedly to reward brokers for helping rig Libor, as "corrupt." The Swiss bank admitted wrongdoing when it settled Libor-rigging charges with U.S. and British authorities last December.