This case study describes the COPA’s quasi-regulatory approach to ongoing oversight of the Mission Health merger in Asheville, North Carolina; examines available performance data; and illustrates the policy challenges of combining regulatory and antitrust approaches into a workable regime of fiscal oversight. We reviewed available literature on this COPA’s design, operations, and records (as available) and complemented our review with interviews with senior executives at Mission Health and insurers in North Carolina, state officials, and expert observers of the COPA’s effect on health delivery and prices. Interviews were all conducted with a promise of nonattribution. We conclude that this application of the COPA model has some successes, and with modifications a COPA-like approach could provide a useful complement to antitrust enforcement in addressing market power.