In this paper,the conception of net underpricing is put forward.Using the method of the uniform-price share auctions and supposing the institutional investors being homogeneous,risk-neutral with the goal of the maximal expected-utility value,we study the optimal auction strategies of the institutional investors for their request quantity being certain ex ante and deduce the equilibrium expressions of IPO price and its net underpricing.Then we obtain the results that the linear equilibrium auctio...