The Florida State University graduate was a virtual unknown in investing circles when Warren Buffett hired him in 2010 to manage a portion of Berkshire’s vast stock portfolio. At the time, one of the few photos that news outlets could find of him was a boyish high school yearbook shot. Since then the world hasn’t gotten to know Combs much better. Over the past seven years, Combs has become an influential figure at Buffett’s conglomerate. In addition to investing a slug of Berkshire’s money, he was behind the $37 billion purchase of Precision Castparts Corp., a supplier to the global aerospace industry, and worked on well-publicized trades that saved hundreds of millions of dollars in taxes. Combs is already in line to manage a huge swath of Berkshire’s investments when Buffett, 87, leaves the scene. But his ever-growing portfolio has led some shareholders and analysts to speculate that he could one day become CEO as well. What Combs does know is financial services. A native of Sarasota, Fla., he graduated from college in 1993 and took a job with the state’s banking regulator. From there he went on to Progressive Corp., working in a group that studied risk and determined what to charge for auto policies. In 2000, Combs started his MBA at Columbia Business School. It was a chance to learn securities analysis in the same halls where Buffett had long ago learned the craft from Benjamin Graham, the father of value investing. Buffett’s advice about reading stuck with Combs as he started his investment career, first as a financial-services analyst at Copper Arch Capital and later at Castle Point Capital Management, the hedge fund in Greenwich, Conn., he started in 2005. Combs’s approach was a race against the clock to consume information. In 2010, Combs asked Buffett’s longtime business partner, Berkshire Vice Chairman Charles Munger, for a meeting. Combs joined Berkshire early in 2011 and eventually moved his family to Omaha from Connecticut. Ted Weschler, the other investment manager Buffett hired to pick stocks at Berkshire, chose to stay in Charlottesville, Va. In addition to JPMorgan, Combs is a director of a few Berkshire subsidiaries, including Precision Castparts and Duracell, the battery maker Berkshire purchased from Procter & Gamble Co. in a tax-saving stock swap Combs negotiated. Less well-known is the time Combs spends hobnobbing with people at the top of the business world. In January he was with Buffett at a Washington luncheon hosted by Vernon Jordan, the Democratic power broker, before the annual Alfalfa Club dinner, a black-tie event where billionaires and politicians mingle. U.S. Secretary of Commerce Wilbur Ross and Dimon were also there.