The impact of global major customers on corporate carbon disclosure: a quasi-natural experiment from Apple’s supply chain in China

This study investigates whether and how global major customers affect corporate carbon disclosure. Leveraging the unique quasi-natural experiment of Apple’s supply chain from 2008 to 2023 in China, we employ a difference-in-differences design and examine the impact of major customers on suppliers’ carbon-disclosure quality. Baseline results indicate that the carbon-disclosure quality increases by approximately 6.76% following a firm’s entry into the supply chain. Mechanism analysis indicates Apple plays a disciplining role through direct governance and indirect exposure effects. Cross-sectional analyses reveal that the impact is more pronounced among suppliers with stronger financial capacity and lower agency costs. Real effects, measured by carbon emission intensity and green innovation, demonstrate that the influence of global major customers extends beyond symbolic disclosure to substantive environmental action. These findings underscore the influential role of major customers in promoting environmental transparency along global supply chains.