Huge changes are underway at Citi as 3 senior execs are stepping down — including CFO John Gerspach (C)

Huge changes are underway at the top levels of Citigroup, with three senior executives set to depart the firm.
CFO John Gerspach is retiring next March, according to an internal memo from CEO Michael Corbat. 
Jim Cowles, the CEO of the bank's operations in Europe, the Middle East, and Africa, is leaving to start a nonprofit at the end of this year, and Bill Mills, the CEO of North American operations, will retire at the end of the year, according to the memo.
Additionally, Corbat announced