We study how search and information frictions shape market dynamics in global e-commerce. Observational data and self-collected quality measures from AliExpress establish the existence of search and information frictions. A randomized experiment that offers new exporters exogenous demand and information shocks demonstrates the potential role of sales accumulation in enhancing seller visibility and overcoming these demand frictions. However, we show theoretically and quantitatively that this demand-reinforcement mechanism is undermined by the large number of online exporters. Our structural model rationalizes the experimental findings and quantifies efficiency gains from reducing the number of inactive sellers.