Order-level data reveal the impact of enterprises' behavior on their profits in China's national ETS

China's national carbon emissions trading system (ETS) has become the largest carbon market worldwide and is considered an effective policy tool for addressing the challenges of climate change. ETS significantly affects corporate profitability and revenue generation, but research on this aspect remains limited. This study employs mediation and moderation effect models, using unit-level monitoring and order-specific trading data from the first compliance phase of national ETS (including 5520 units from 2162 power firms) in China, to estimate the impact of enterprises' responses to the ETS. The results highlight several important insights. First, enterprises' positive responses to the market (such as using high-quality fuel) are positively correlated with revenue and profit (i.e. net sales and compliance rate), with carbon intensity playing a significant mediating role in this relationship. Second, heterogeneity analysis reveals variations across different types of units and regions, with smaller units and those in western regions exhibiting greater sensitivity to compliance. Third, compared to the less experienced national market, pilot markets show a greater propensity to sell allowances and ensure compliance with emission targets. This study provides a more micro-level perspective on how China's ETS influences enterprises and offers policy-relevant evidence to inform decision-making.