Citigroup Inc. and Merrill Lynch & Co. Inc. need to find credible chief executives fast. But that won’t be the magic salve for all their problems. Their former leaders’ penchant for seeing off potential rivals, as well as the brain drain to hedge funds, has left their senior ranks depleted, too. The trouble is, especially for Citi, that the list of qualified candidates to work just under the boss isn’t a long one.

Merrill’s smaller size gives it the advantage of being less complex, relatively speaking. Its challenge is to find fixed income-savvy executives to give investors comfort that the Thundering Herd’s risk-taking is under control. Luring Larry Fink as new chief would help tremendously, considering his success running bond manager BlackRock Inc. and his background in structured products. He might even bring some of his colleagues with him, could poach talent from the likes of Goldman Sachs Group Inc. or Lehman Brothers Inc. or, at a stretch, even entice a few savvy hedge fund types back to Wall Street. Citi will need more. But even in the pool for the top job, few have experience in enough of the US megabank’s sprawling retail and investment banking businesses, not to mention the ability to manage its gargantuan balancesheet. For example, NYSE Euronext’s John Thain, a much-touted candidate, doesn’t. That’s why Citi’s board ought also to think about finding a strong lieutenant or two for the new chief, too, alongside Gary Crittenden, the respected chief financial officer.

But who? One candidate could be KKR Financial Llc. boss Nino Fanlo. A former treasurer at Wells Fargo & Co., he certainly knows balance sheets. The two others are PNC Financial Services Group Inc.’s vice-chairman William Demchak and Bank of America Corp.’s ex-finance chief, Al de Molina. These three men have the kind of backgrounds Citi desperately needs to reassure its shareholders that the bank can find its feet again.