This paper investigates the relationship between CO2 emissions and cross-bordermergers and acquisitions (M&A). It does so using country-level data on CO2 emissions and cross-border transactions from the period 2000-2020. The paper focuses on two main aspects: asymmetry concerning income levels of both target and acquirer nations and sector-specific effects. First, the paper tests whether M&As from a high-income country (acquiring country) reduce CO2 emissions. Second, it tests whether only M&A in polluting sectors affect CO2 emissions. The main finding of the paper is that what matters for the impact of cross-border M&A on pollution is not where it is coming from but where it is going. M&A going to a high-income country reduces emissions while M&A going to a low-income country increases emissions. Furthermore, the paper finds mixed evidence of sector-specific effects which calls for further research and rethinking of sector disaggregation.