Citigroup Inc named investment bank chief John Havens president and chief operating officer on Wednesday, expanding its most senior level of executives and elevating a long-time adviser to Chief Executive Officer Vikram Pandit.

Havens, currently head of Citigroup's institutional clients group, will fill a vacant role as he takes charge of the bank's day-to-day operations. The company announced his promotion along with several other management changes on Wednesday.

Citigroup's investment bank has struggled recently, falling to eighth place from fourth in Thomson Reuters' rankings of the high-profit mergers and acquisitions business. Citigroup announced it was promoting Havens a day after the company reported a worse-than-expected fourth-quarter profit, due largely to a steep drop in the investment bank's bond-trading revenue.

After years at Morgan Stanley, Havens left with Pandit to form the Old Lane hedge fund with him in 2005. Citigroup bought the fund for $800 million in 2007, and by the end of that year had named Pandit CEO.

Shares of Citigroup were up 1 cent at $4.81 in trading before the market opened.

(Reporting by Maria Aspan; Editing by Lisa Von Ahn)