During the trial that began on May 20, the government highlighted a Sept. 23, 2008, phone call it said was made from Gupta to Rajaratnam. The call came only minutes after Gupta had learned during a confidential conference call about how Warren Buffett's Berkshire Hathaway planned to invest $5 billion in Goldman — a blockbuster deal that wouldn't be announced until the stock market closed at 4 p.m.