In the course of the liberalization of European energy markets, the German government opted-diverging from all other European countries-for Negotiated Third-Party Access. In this article we analyze if, theoretically, this institutional regime can be superior to regulation. We review empirically whether certain aspects of the actual implementation, in particular publication of the network access charges for each network supplier, facilitated or inhibited competition. In the first place we reconsider previous research, showing that NTPA can-under certain conditions-be economically effective. Our empirical analysis shows that the duty of publishing access charges supported market transparency and imposed a regulatory threat, particularly to suppliers with significantly above-average charges. On the other hand observable price adjustments over time serve as an indicator of tacit collusion. Although the expensive suppliers cut their prices, the cheaper ones raised theirs.