The presentation focuses on the perceived “oligopoly gap” in the European Union (“EU”) competition rules. To date, tacit collusion has primarily been dealt with ex ante, through the enforcement of the EU merger regulation. Given, however, that the structural approach of tacit collusion through merger control rules is fraught with numerous shortcomings, the presentation explores to what extent the behavioral rules of conduct enshrined in Article 101 and 102 TFEU can be enforced with a view to remedy, ex post, tacit collusion on oligopolistic markets. The issue is considered from both a substantive perspective – in particular it offers a novel interpretation of the cryptic concept of abuse of joint dominance on oligopolistic markets – and from an institutional standpoint – it proposes, de lege lata, a specific enforcement process, which alleviates risks of false positives and protects legal certainty.