Mechanisms Through Which Supply Chain Vertical Integration Improves Corporate Debt Financing Costs: A Multi-Case Study of BYD, NIO and XPeng

Against the backdrop of volatile global raw material prices and supply chain restructuring, the new energy vehicle (NEV) industry exhibits two coexisting modes of supply chain organization, namely vertical integration on the one hand and external procurement or contract manufacturing on the other. Taking BYD as the focal case and NIO and XPeng as comparative cases, and drawing on the three companies’ public annual reports, bond offering circulars, credit rating reports and ESG reports for 2020 to 2025, this paper investigates through which channels supply chain vertical integration affects corporate debt financing costs. The analysis proceeds along the transaction cost line and the information disclosure line, and examines under what conditions digitalization, institutional complexity and ESG performance strengthen or weaken this process. The findings are interpreted on the basis of transaction cost theory and information asymmetry theory, and the divergence in measurement arising from accounting-based indicators of debt cost is clarified.