Citigroup CEO Vikram Pandit has resigned today. According to the Wall Street Journal, Pandit, who was appointed CEO in 2007 and led the group during the 2008 financial crisis and later helped double its profit, "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."

Citigroup Chairman Michael O'Neill said, "We respect Vikram’s decision. Since his appointment at the start of the financial crisis until the present time, Vikram has restructured and recapitalized the Company, strengthened our global franchise and re-focused the business. The Board and I are grateful to Vikram for his leadership, integrity and resilience in guiding Citi through the crisis and positioning it well for the future. We wish him all the best with the next stage in his career."

The NY Times reports, "His resignation comes after long-simmering tensions with the bank’s board. In particular, the board’s chairman, Michael E. O’Neill, had been increasingly critical of Mr. Pandit’s management of the sprawling global bank, according to several people close to the bank." A source said, "[Pandit] was considered more technically skilled" versus being agile enough to react to execute strategy.

Pandit's successor is Mike Corbat, the board's unanimous choice, who was Citigroup’s CEO of Europe, Middle East and Africa. O'Neill said of Corbat, "He has managed numerous institutional businesses, including sales and trading, capital markets, corporate and commercial banking, and such consumer businesses as wealth management, mortgages and credit cards. During the financial crisis, he successfully led the divestiture of more than 40 businesses, helping to strengthen the Company’s balance sheet substantially. In this role, he also restructured and rebuilt a number of the Company’s consumer-facing businesses, including the mortgage and credit card businesses."

Yesterday, Citigroup had announced strong quarterly earnings. An asset manager, Mike Holland, told Reuters, "It's not a shock that (Pandit) is no longer there, but the surprise is this is all happening very quickly. Why is he leaving immediately?" And Pandit's longtime associate and Citigroup President John Havens also stepped down, prompting to Holland say, "I'm not a Citi shareholder, but if I were, I'd be disappointed that Havens is gone, in some ways more than Pandit."

Citigroup has, according to its news release, "approximately 200 million customer accounts and does business in more than 160 countries and jurisdictions," which makes it the third largest bank on earth.