The Lead Goose Effect of Chain Leaders: ESG Responsibility Spillovers on Supply Chain Environmental Investment—Mediating Channels and Heterogeneous Evidence from China’s A-Share Market

Against China’s dual-carbon goals, carbon emissions and pollution transfer across supply chains hinder systemic low-carbon transformation; the prior literature on ESG and corporate environmental investment mainly focuses on individual firm-level effects, ignoring the unique lead goose governance function of core chain leader enterprises in supply chain networks and their internal transmission mechanisms. Drawing on stakeholder theory, this paper constructs a collaborative green supply chain governance framework led by chain leaders to fill the above research gaps. Based on a sample of Shanghai and Shenzhen A-share listed firms from 2011 to 2023, we identify chain leaders by combining official industrial chain leader lists and total asset threshold standards, with baseline ESG data from Wind and alternative Bloomberg ESG scores for robustness. Two-stage least squares instrumental variable regression addresses endogeneity, while omitted variable sensitivity analysis, indicator replacement and stepwise high-dimensional fixed effects ensure reliable empirical conclusions. The results provide evidence of a significant lead goose spillover effect: each one-unit improvement in chain leaders’ ESG performance is associated with an 8.33% increase in upstream suppliers’ environmental investment at the 1% significance level and downstream clients’ environmental investment by 3.54% at the 5% significance level, yet non-leader enterprises generate no meaningful spillover impacts, and the effect is stronger for upstream partners. Mechanism tests support two core mediating channels: chain leaders’ ESG performance stimulates supply-chain green investment by fostering environmental sensitivity salience and cutting inter-firm transaction costs. Heterogeneity analysis shows the spillover effect is amplified in polluting industries and highly concentrated supply chains. This research extends the emerging literature on supply chain ESG spillovers by documenting the lead goose effect of formally identified chain leaders on partners’ actual environmental investment, distinguishing directional asymmetry, and unveiling dual mediating mechanisms.