Citigroup has reshuffled its senior managerial ranks, naming new heads for three of its main businesses in an effort by Vikram Pandit, chief executive, to consolidate his hold on the company.

The changes – announced Monday with a raft of internal memos – include the expected confirmation of Mike Corbat, a 25-year company veteran, as head of Citi Holdings, a collection of non-core businesses that will be sold or wound down.