Goldman Sachs is partnering with American Express to upgrade its digital cash management offering, CNBC has learned. The investment bank is leaning on the world's biggest issuer of business charge cards in its quest to displace rivals that handle trillions of dollars in deposits and payments for corporations. By integrating virtual card technology from AmEx into its platform, Goldman has automated the cumbersome process of sorting and paying bills to vendors and suppliers, according to executives of the two firms. "This a one-stop solution to a highly fragmented business-to-business payments landscape for large corporates," Hari Moorthy, Goldman's global head of transaction banking, said in a phone interview. "It lets CFOs and treasurers have better financial planning because now you have a seamless way to track the flow of funds, irrespective of the payment rails used."