Brand acquisitions are a popular growth strategy. However, both anecdotal evidence and initial empirical evidence suggest that acquisitions can harm the acquired brand. This article proposes and tests a theoretical framework that aims to explain when and why consumers react negatively to acquired brands. Across ten studies using different methods, research designs, product categories, and brands, the authors demonstrate that these negative brand reactions can be explained by the perceived loss of a brand's unique values. Building on this values authenticity account, they document that the negative effect of acquisitions depends on the acquired brand's values, brand age, leadership continuity, and the alignment between acquiring and acquired brands. The findings offer important theoretical and managerial implications, helping managers predict and mitigate the negative effects of acquisitions for brands.