The moves, which emerged from recent business reviews, are the latest in a series of changes that Mr. Pandit has made since taking over for Charles O. Prince III in December. Citigroup has been hard hit by the credit crisis, with more than $20 billion in write-offs and a 60 percent drop in its stock price over the last year.

Besides strengthening its balance sheet, Mr. Pandit has appointed a new chief risk officer and made changes in the way its mortgage operations and global wealth management unit are structured. Even so, investors continue to raise concerns about its financial health as it braces for billions of dollars in additional losses.

The moves also illustrate the organizational and personnel challenges facing Mr. Pandit, who must be part psychologist and chess master overseeing Citigroup’s brutally political culture. “By putting the right talent in the right places, we are enhancing Citi’s ability to meet the needs of our institutional clients,” Mr. Pandit said in a statement.

The appointment was reported Monday by The Wall Street Journal.

Mr. Klein is widely viewed as a brilliant relationship banker and has been enormously influential in helping Citigroup raise new capital with his strong ties to Middle East investors. But he was considered a poor manager who did not like to share authority. His spats with Thomas Maheras, his co-head at the investment bank, provided a steady stream of gossip throughout the company.

Mr. Klein has also threatened to quit on several occasions, according to people close to the company. Last fall, as Mr. Prince considered a plan to name Mr. Pandit the head of the investment bank, he said he would leave if he were effectively demoted. Mr. Klein denies that he ever threatened to leave, according to a person briefed on his thinking.