This study examines the impact of acquisitions in the healthcare market on procedure prices in São Paulo. Our hypothesis is that acquisitions provide health insurance companies with greater bargaining power, enabling them to negotiate lower prices with hospitals. We analyze five acquisition events be tween June 2018 and December 2020 using a difference-in-differences approach, including a staggered analysis to account for the varying timing of these events. Our findings show a significant reduction in the prices of birth procedures, including vaginal and cesarean deliveries, following the acquisitions, while the impact on ICU procedures and hospital consultations is less clear, with no con sistent or significant price changes detected. These results suggest that while acquisitions may drive down prices for certain high-frequency procedures, their effect on more specialized services is more limited. This research contributes to the understanding of how market power dynamics in the healthcare sector influence procedure pricing.