Warren Buffett still key Apple investor after selling shares after iPhone slump

Berkshire Hathaway CEO stressed relationship at annual meeting attracting Apple CEO Tim Cook, Bill Gates and Bill MurrayThe billionaire investment tycoon Warren Buffett has stressed his empire will remain a key investor in Apple after it sold billions of dollars’ worth of shares in the iPhone maker.Thousands of shareholders in Berkshire Hathaway, Buffett’s sprawling conglomerate, have flocked to Omaha, Nebraska, for the firm’s annual meeting – dubbed Woodstock for Capital