Business-to-business (B2B) payments are the biggest opportunity in domestic and cross-border payments for card issuers, accounts payable (AP) & accounts receivable (AR) invoice software providers, payment processors, network operators, and supply chain finance (working capital) companies. American Express has initiated several efforts over the last 18 months to expand card payments tied to AR & AP automation, including partnerships with Wex, MineralTree, and Cvent. Its latest effort is Vendor Pay by Bill.com, a partnership with Bill.com, pr...