In his 50 years at the helm of Berkshire Hathaway Inc, Warren Buffett has transformed a failing textile company into a sprawling conglomerate that has vastly outperformed most of the rest of corporate America. In the 84-year-old’s annual shareholder letter released on Saturday, Buffett said Berkshire has grown so large – 751,000 times its original net worth per share – that the future pace of gains “will not come close” to those of the past. “The numbers have become too big,” Buffett wrote.