The international gas and electricity markets could be described as bilateral oligopolies. Both sides of the market are formed by a limited number of firms; the few exporters on the supply side and the few importers on the demand side are unlikely to be price-takers. The paper aims at describing what the state-of-art in the economics research suggests about the determination of prices in such markets and about the role
of the relative concentration of the two sides of the market. In particular, the paper focuses on the findings of three main strands of literature. First, it describes the results of bargaining theory when the agents negotiating over the price of an indivisible good are more than two. Even for the case of one seller and two different buyers, the price emerging from the negotiation while it is clearly different from the bilateral monopoly case it could also diverge from the competitive outcome, as well as from the prediction of the auction theory. For the case of bargaining between two sellers and two different buyers, some seminal
models have recently been studied, confirming how sensibly the price is affected by the structure of a «thin» market. Secondly, the paper presents some considerations about the role of relative concentration
of the two sides of the market. The hypothesis of existence of some degree of «countervailing power» is discussed. Finally, the focus on the infra-structural networks typically observed in the electricity and gas markets, leads to consider the findings of the recent literature on two-sided network markets.