Xero is acquiring Melio for $2.5 billion to enhance its accounts receivable (AR) and accounts payable (AP) capabilities in response to QuickBooks' growing dominance in the U.S. market. With Melio's strong U.S. customer base and significant revenue, this acquisition aims to boost Xero's market presence and cross-sell opportunities, although challenges remain in integrating services and convincing Melio's existing clients to switch accounting software.