The usual analysis of bidding in first-price auctions assumes that bidders know the distribution of valuations. We analyze first-price auctions in which bidders do not know the precise distribution of their competitors' valuations, but only the mean of the distribution. We propose a novel...

For two symmetric bidders, weak monotonicity conditions are shown to imply existence of an equilibrium in mixed behavioral strategies for a sealed-bid first-price auction of an item for which each bidder's value depends on every bidder's observed signal. Such an equilibrium has atomless...