Private equity maven walked away from $25 billion buyout of Sallie Mae last December after 8 months of delays; student loan firm's deteriorating finances amid worsening credit crisis halted deal. Founded buyout shop J. C. Flowers & Co. 1998. With Timothy Collins, bought Long Term Credit Bank of Japan in 2000; first time foreign investors owned a major Japanese bank. Improved asset quality, renamed Shinsei Bank. Took public 2004; partners reaped $2.3 billion. Last year bank reported $260 million in subprime-related writedowns; Flowers provided $500 million cash infusion. Considered buying Bear Stearns during financial giant's meltdown; edged out by JPMorgan. Other investments include Enstar Group (financial services).