As a stock exchange dedicated to small and medium enterprises (SMEs), the success of the Alternative Investment Market (AIM) has established this segment of the London Stock Exchange as the benchmark, of which the Alternext is considered a flawed copy. This article aims to invalidate this proposition. First, the performance of Alternext (2005-2012), if compared to AIM’s performance at the same stage of development, is not as bad as critiques have been deluded the public into believing. Second, AIM characteristics are not set up as a stock exchange model dedicated to medium and small enterprises: the success seems to be based less on the services which AIM provides to small or innovative companies than on the regulatory arbitrage realized by medium and large companies. This observation acutely raises the question of the nature and organization of a stock exchange adapted to the specifications of SMEs.