Small suppliers often face challenges to obtain financing for their operations. Especially in developing economies, traditional financing methods can be very costly or unavailable for such suppliers. In order to reduce channel costs, in recent years large buyers started to implement their own financing methods that intermediate between suppliers and financing institutions. In this paper, we analyze the role and efficiency of buyer intermediation in supplier financing (BIF). Building a theoretical model, we show that without buyer intermediation, traditional supplier financing can be inefficient and can significantly reduce supply chain performance. Using data from a large Chinese online retailer, we demonstrate that BIF induces lower wholesale prices and higher order quantities. Through structural regression estimation, we demonstrate that the retailer overestimates the demand by 10-15%. We also show that the financed suppliers have cash positions of only about 56% of their operating costs, and that BIF improved channel profits by approximately 16.7%, yielding significant annual savings for the retailer.