Sustainability has thus far not been a key topic for the assessment of concentrations by the European Commission or National Competition Authorities when it comes to merger control. The chairman of the Dutch Competition Authority (“ACM”), Martijn Snoep, for example, mentioned during a webinar organised by the Dutch branch of ICC at the end of 2021 that the ACM is more reluctant to accept ‘green efficiencies’ (efficiencies leading to a reduction in environmental damage) in merger control cases. This is because the approval of a merger brings a structural change to the competitive structure in the relevant market(s). If the claimed environmental efficiencies do not materialise, or materialise only to an insufficient extent, the concentration is still irreversible, and the hands of the authority are basically tied. In this article, we will go a bit more in-depth into the role that sustainability could – and perhaps should – play in merger control.