Robert E. Diamond Jr., the chief executive of Barclays, resigned today, less than a week after the British bank agreed to pay $450 million to settle accusations that it had tried to manipulate key interest rates for its own benefit, the New York Times DealBook Blog reported yesterday. Diamond's resignation, which was effective immediately, comes after mounting criticism of the bank's actions from politicians and shareholders. Prime Minister David Cameron had called on individuals within the bank to take responsibility, while other British politicians had said Diamond should resign. Jerry del Missier, who was promoted to Barclays' chief operating officer last month, is expected to resign as part of the shake-up following the rate manipulation scandal.