Based on the economics of scope theory, this paper analyzes the influence of diversification on the market valuation of commercial banks. Based on the OLS regression model, the accounting data of 360 commercial banks over the period of 2010-2020 is empirically tested. The results demonstrated the existence of scope economics from diversification: the market assigns diversification premium to financial conglomerates for their engagements in multiple businesses. While difficult to identify a single causal variable, the results are consistent with the literature that stress the emerging scope economics caused by technological spillovers.