Warren Buffett"s Berkshire Hathaway Inc (BRKa.N) on Saturday said first-quarter operating profit rose 20%, and that it extended its recent aggressive stock repurchases by buying back $6.6 billion of its own stock. Operating profit increased to $7.02 billion, from $5.87 billion a year earlier. Berkshire also reported net income of $11.71 billion, or $7,638 per Class A share, compared with a net loss of $49.75 billion, or $30,653 per share, a year earlier. Our Standards: The Thomson Reuters Trust Principles.