Citigroup chief executive Vikram Pandit abruptly stepped down following a clash with the New York company's board over strategy and operating performance at businesses including its institutional clients group, according to people with knowledge of the bank.

Pandit and his top aide, John Havens, Citigroup's president and chief operating officer, resigned on Tuesday. The nation's third-largest bank by assets named Mike Corbat as Pandit's successor.