Investors who possess information about the value of an IPO can participate in the offering as well as trade strategically in the aftermarket. Both the bookbuilding and the fixed price IPO selling methods require more underpricing when aftermarket trading by informed investors is considered. Bookbuilding becomes especially costly, since the potential for profit in the aftermarket adversely affects investors’ bidding behavior in the premarket. Unless the underwriter building a book can target a small enough subset of the informed investors, a fixed price strategy that allocates the issue to retail investors produces higher proceeds on average, contrary to the conventional wisdom in the literature. We therefore find a benefit to limiting access to the premarket and, hence, provide an efficiency rationale for the practice by American bankers of marketing IPOs to a select group of investors.