How does carbon emission trading scheme affect enterprise market value? A roadmap towards natural resources sustainability

China has committed to establishing a unified national carbon emissions market to achieve carbon reduction goals. The Carbon Emission Trading Scheme (CETS) internalizes emission reduction costs, which may affect enterprise market value (EMV), but this has seldom received attention. Therefore, based on A-share listed enterprises data from 2009 to 2019, this study not only focuses on investigating the direct and heterogeneous impact of CETS on EMV but also identifies the effective market mechanism design by constructing a unified research framework including carbon emission quota allocation schemes, penalty mechanisms, and EMV performance. The empirical results are as follows: (1) The CETS can significantly enhance the EMV of covered enterprises, indicating that China's CETS supports the Porter hypothesis. Compared with state-owned and small enterprises, the CETS has a more significant effect on promoting the EMV of non-state-owned and large enterprises. (2) The mixed carbon quota allocation scheme (the combination of free and auction schemes) is more effective in improving EMV than the pure free quota allocation system. Meanwhile, the mixed penalties combining economic and non-economic measures can effectively encourage CETS-covered enterprises to participate in carbon trading activities, thus enhancing overall EMV. (3) The results of the mediation effect test indicate that the mixed schemes improve EMV by promoting low-carbon technology innovation, and mixed carbon quota allocation schemes have a more significant effect through this channel. These findings have important reference value for improving EMV under the CTEs, achieving the carbon peak and carbon neutrality goals, and promoting sustainable economic development.