Updated from 2:00 p.m. EDTGoldman Sachs ( GS) investment banker Byron Trott is leaving the company to start his own merchant banking firm with backing from Warren Buffett, according to a source familiar with situation and a published report. Goldman CEO Lloyd Blankfein recently made a visit to Chicago for a town hall meeting of the bank's employees there, and ended up having to deal with Trott's departure during his visit, according to one banker at a rival firm. Trott works out of the firm's Chicago office. Trott is raising as much as $2 billion for a fund that will invest in family-controlled and entrepreneurial companies, The Wall Street Journal reported Monday morning. Buffett told the Journal that Berkshire Hathaway ( BRK-A) will invest in Trott's firm, to be called BDT Capital Partners. Buffett has praised the banker on two separate occasions in his annual letter to shareholders, writing that Trott is "a rare investment banker who puts himself in his client's shoes," adding, "I trust him completely." Trott was the banker that advised Buffett on his $5 billion investment in Goldman last year and he was also behind a $3 billion Buffett infusion into General Electric ( GE), according to report in The New York Times last year. Before he became an investment banker, Trott worked in the Goldman "private client" unit that advises wealthy families. That's how he got to know both the Mars and Wrigley families, heirs of the candy companies that came together in a $23 billion deal last year. Trott advised Wrigley on the deal, and Goldman Sachs and Berkshire Hathaway each contributed several million to help Mars make the purchase.