Citi CIO Marty Lippert has left the bank after just eight months in the job, returning to his native Canada "for personal reasons".
Lippert was hired by Citi chief Vikram Pandit in July last year with a brief to overhaul the bank's sprawling IT infrastructure.
At the time, Pandit said: "Marty's appointment emphasises the importance we place on technology in driving enterprise transformation, and we'll look to him to be a key architect of that change."
Lippert, previously head of global technology and operations at RBC, had filled a spot vacated the previous December, when Marvin Adams moved to a Fidelity Investments unit.
In an internal memo to staff, Citi's chief administrative officer Don Callahan says Lippert had made "significant progress" in streamlining and integrating the bank's global operations and technology, lowering costs and increasing productivity across the company.
The memo states: "Unfortunately for Citi, Marty has decided to return home to Canada for personal reasons. We recognise this was not an easy decision for him, especially given the progress he and his team have made in such a short time."
Callahan says he will take on Lippert's duties in the interim until a suitable replacement can be found.