In this paper, we consider a dynamic game of incomplete information used to sell sponsored search advertisements. We also consider a corresponding static game of complete information. We analyze the underlying dynamic game of incomplete information, and we establish an upper bound on the revenue of any equilibrium of any dynamic game in this environment. We then exclude equlibria of the corresponding static game with revenue that exceeds this upper bound. We characterize optimal reserve prices and show that the optimal reserve price is independent of the number of bidders and independent of the rate at which click-through rate declines over positions. We show that most of the incremental revenue from setting a reserve price optimally comes not from the low bidder's direct effect, and not from indirect effects of other low bidders, but rather from the indirect effects on high bidders.