In this paper, we study how the interbank market could impact deposit competition and bank profits. We first document two stylized facts: the net interbank funding ratio is negatively correlated with net interest margin (NIM), as well as with the cost-to-income ratio (CIR). To rationalize these two facts, we embed the interbank market into a BLP model framework. The model is calibrated using Chinese listed banks’ data. A counterfactual experiment reveals that shutting down the interbank market will lead to a decline in NIM and bank profits. Our results indicate that the interbank market can facilitate specialization and reduce the intensity of deposit competition.Published version