Visibility is a core allocation mechanism in digital markets. This paper develops a dynamic empirical framework in which platform-induced visibility changes act as exposure shocks that transmit through consumer attention and seller response. Using within-product event-time variation from a large online marketplace, the analysis estimates the dynamic effect of visibility improvements on demand and pricing. The main event-study results show that visibility gains generate large, immediate, and persistent increases in demand, while price responses are positive but smaller and slower. The paper’s main contribution is to embed visibility in a mechanism-based decomposition that separates exposure transmission from behavioral adjustment, thereby linking reduced-form estimates to economically interpretable components. This framework clarifies whether platform design operates through consumer discovery, seller pricing, or both. The evidence indicates that attention-driven demand amplification is the dominant channel. Effects are stronger for low-substitutability products and smaller sellers, consistent with binding exposure constraints. The findings imply that algorithmic discoverability has important consequences for competition, seller inequality, and market efficiency.