These days, the CFO job at a financial-services firm is the perfect gig for a short-timer. Unlike at big tech companies -- where a chief financial officer often can hang on for years just balancing the books and exercising stock options -- the lifespan of a CFO on Wall Street increasingly seems to be measured in months. In December, Al de Molina resigned as Bank of America's ( BAC) CFO, just 18 months after getting the job. On Monday, investors learned that Sallie Krawcheck's tenure as Citigroup's ( C) top financing officer won't be much longer than Molina's. Krawcheck, who is moving back to run Citigroup's brokerage, private banking and stock research operations, became CFO just over two years ago, in September 2004. In her quick turnaround, Krawcheck is hardly alone. Jerome Bailey, who left insurance broker Marsh & McClennan ( MMC) early last year to become the CFO of the New York Mercantile Exchange ( NMX), lasted just seven months at Nymex. The exchange pushed Bailey out the door on the eve of its highly successful IPO last November. In many ways, the CFO position on Wall Street is a thankless job with little glamour -- even if it is certainly well-compensated. For many, it's either a stepping stone to a better job, or a temporary stint. The job of the CFO at all companies has become increasingly more stressful with the stiffened reporting mandates under the Sarbanes/Oxley corporate governance reform law. But bank CFOs have had the added pressure of dealing with a tricky interest rate environment, which makes it hard for lenders to find high-yielding investment opportunities to reinvest customer deposits.