Private Equity Rollups of Physician Practices: Evidence from Gastroenterologytechnical_reportsThe competitive effects of emerging “platform and add-on” consolidation strategies, which often escape regulatory scrutiny, remain understudied. We examine whether private equity (PE) rollups affect prices through changes in local market power, PE-specific mechanisms, or both, using a difference-in-differences design and novel hand-compiled data on platform and add-on acquisitions by 7 PE firms in gastroenterology. We find that both initial platform and add-on acquisitions increase prices, with add-on acquisitions generating larger effects. Within-market add-ons, which increase acquiring firms' market share by approximately 14 percentage points, raise prices by 10%. Cross-market acquisitions in geographically distinct markets, which by construction leave local market concentration unchanged, raise prices by 3%. Cross-market price increases reflect the diffusion of platform pricing strategies, whereby acquired practices rapidly converge to the negotiated rates established by their PE-backed platforms. We find no evidence of changes to patient outcomes or patient selection. Overall, our findings suggest that regulatory frameworks focused exclusively on local market concentration may understate the cumulative competitive effects of rollup acquisitions, with implications for antitrust enforcement and the ongoing policy debate over whether PE-specific regulatory treatment is warranted.Yashaswini SinghAuthorChristopher M. WhaleyAuthor2026private equityPhysician PracticesRollupsWorking PaperAll rights reservedIn CopyrightAll Rights Reserved10.26300/gxsx-7y24