This paper considers equilibrium in transaction mechanisms. In an envi
ronment with homogeneous buyers and sellers, which eliminates the adva
ntage auctions possess of matching buyers and sellers, both auctions a
nd bargaining are equilibria. However, only auctions are evolutionaril
y stable. This identifies a new advantage of auctions over bargaining,
arising from the division of the gains from trade. (C) 1996 Academic
Press, Inc.