Berkshire Hathaway shares fell on Friday, a day after CEO Warren Buffett left following a 60-year run. The 95-year-old officially stepped down on Thursday, and successor Greg Abel, who started at Berkshire in 2000 and served as vice chairman of its board of directors, took over on Friday.In afternoon trading on Friday, Class A shares of Berkshire Hathaway had fallen 1.5% by 3 p.m. ET. In Warren’s last year as CEO, the conglomerate gained 10.9%, according to CNBC.BUFFETT SPARKS UNITEDHEALTH'S BIGGEST WEEKLY ...