Mergers and acquisitions are important activities for the growth of firms. In the energy sector, acquiring firms can obtain eco‐friendly technology and premiums, as well as tangible assets, through the acquisition of energy firms. Among many energy firms, an acquired startup is more effective since the acquisition price is relatively inexpensive and the acquiring firm is also exposed to entrepreneurial culture. In this study, to test the acquisition effect, datasets from Worldscope and CrunchBase are used. It is observed that, despite the advantages of an acquisition, the effect of a startup acquisition is negative. However, firms in environmentally sensitive industries benefit from such acquisition activity. The acquisition price of energy startups is overestimated due to increasing demand for acquisitions. On the other hand, the eco‐premiums also help dirty firms make a profit.