Today, a large Berkshire Hathaway mystery lifted when a Greenwich, Conn., hedge fund, Castle Point Capital Management, quietly advised its investors that the fund's managing partner, Todd Anthony Combs, would leave to join Berkshire at the end of the year.

    Behind that simple fact is a big story: Combs, a mere 39, will with this move become the leading contender to eventually succeed Warren Buffett as manager of Berkshire's billions in investments.

    The word "investment" is key to that last sentence. As chairman of Berkshire, Buffett has two jobs: He runs the business as CEO, and he manages Berkshire's huge investments in securities. It is the investment job for which Combs is the leading contender.

    Buffett's hiring of Combs at least partially satisfies a commitment Buffett made to Berkshire's shareholders more than three years ago in his 2007 annual letter, published in March that year. Buffett said were he to die "tonight," the company would have three outstanding candidates for the CEO half of his job. On the investment side, however he conceded that good candidates were not lined up in the wings.

    Buffett therefore announced that he, with the help of vice chairman Charlie Munger and Lou Simpson (who runs the equity investments of Berkshire subsidiary GEICO), would hire one or more men or women to manage part of Berkshire's money.

    The years passed, with no one hired. At each Berkshire (BRKA, Fortune 500) annual meeting, held in the spring, there would be a shareholder question about progress on this important front. Buffett would answer that the search continued.

    Now, with Combs recruited, at least part of the hunt is ended. On that subject, Buffett, who just turned 80, will surely have something expansive to say in his next shareholder letter. Whether he will add that an additional investment manager or two may be hired is not known.

    Talking today to Fortune about Combs, Buffett said he had met him through Charlie Munger, who had thought that Combs would fit in well at Berkshire. Buffett agrees. In a press release Berkshire issued today, Buffett said, "For three years Charlie Munger and I have been looking for someone of Todd's caliber to handle a significant portion of Berkshire's investment portfolio. We are delighted that Todd is joining us."

    Buffett described Combs as an "all-American type" who is not the least bit interested in publicity, an attitude unlikely to shield him from it. Now a resident of Darien, Conn., Combs is by birth a Floridian who graduated in 1993 from Florida State University with majors in finance and multinational business operations.

    Once out of school he worked for Florida's comptroller and later moved to Progressive Insurance, where he was involved in the all-important activity of setting automobile insurance rates. Progressive is an arch-competitor of Berkshire's GEICO.

    Combs' direct route to Berkshire began in 2005 when he began to manage Castle Point, a new long/short hedge fund set up to take positions in financial services companies. Castle Point was seeded with capital by Trident III, one of four Trident funds established over the years by private equity firm Stone Point Capital. Castle Point raised $500 million over two years and began full-scale investing in late 2007.

    A more traumatic moment to start any kind of fund, much less one focused on financial services, can hardly be imagined. The stock market had just months before hit a peak and begun to sink into the chaos of 2008. Had Castle Point been only a "long" fund, it would have met immediate disaster.

    But the fund's short positions apparently saved it. Buffett describes Combs' record through the financial crisis as "pretty good." Combs' hiring, in fact, clearly indicates that Combs has had a performance with which Buffett is satisfied.