The U.S. company ConocoPhillips is buying back stock at an annualized rate of $1.5 billion to return more cash to investors. That’s an increase of 50% compared with the pace of repurchases in the fourth quarter, the point at which the program was suspended in the wake of Conoco’s acquisition of rival producer Concho Resources Inc. The shares rose 1.5% in pre-market trading in New York.