Fujita, Yasunori2018-07-092018-07-092016-04Theoretical Economics Letters, 2016, 6, 208-2132162-2086http://dx.doi.org/10.4236/tel.2016.62023http://hdl.handle.net/123456789/1713By reformulating the Cournot model by making use of the optimal stopping theory, we reconsider the excess entry theorem for a stochastic market. It is revealed that: 1) free entry in a stochastic oligopolistic market is socially excessive, owing not only to the presence of scale economies but also to the value of waiting; 2) welfare maximizing number of the entrants is larger if the market is more uncertain.enExcess Entry TheoremCournot CompetitionOptimal Stopping TheoryGeometric Brownian MotionValue of WaitingArticle