From synergy to spread: How environmental regulation is helping Chinese firms achieve low-carbon expansion — and take their supply chains with them

The synergy between carbon emission reduction and green expansion (CERGE) serves as a strategic orientation for firms to achieve green transformation. As environmental regulations are increasingly employed to promote such green growth, an important question arises as to how these policies can foster CERGE synergy—particularly by extending their influence from large enterprises to the vast number of smaller firms through supply chain linkages. This study aims to examine how the T10000P, as a command-and-control environmental regulation, influences the synergy between CERGE in the context of China's dual carbon goals and green transition. Using a sample of China's A-share listed companies from 2008 to 2020, this paper examines the impact of the top 10,000 enterprise energy saving program (T10000P) on the synergy between CERGE, measured through a coupling coordination model and assessed with a difference-in-differences approach. Results show that T10000P significantly enhances firms' synergy between CERGE, with stronger effects observed in high-tech and non-heavy-pollution industries. Financing constraints negatively moderate this impact, while alleviation of such constraints strengthens the synergy. Additionally, the supply chain spillover effect of T10000P is asymmetric: upstream firms' participation significantly improves downstream firms' synergy between CERGE, whereas downstream participation does not significantly affect upstream firms. This one-way spillover effect is more pronounced when upstream firms have greater bargaining power and closer ties with downstream firms. The findings provide valuable insights for leveraging key enterprises' leading role in supply chains and optimizing environmental regulations to promote industrial green transformation and sustainable development.