This paper studies multiunit common value auctions with informed and less informed bidders. In these auctions, we show that bidders with less information can bid very aggressively and do surprisingly well. We also show that the degree of aggressiveness and sucThis paper studies multiunit common value auctions with informed and less informed bidders. In these auctions, we show that bidders with less information can bid very aggressively and do surprisingly well. We also show that the degree of aggressiveness and success of bidders with less information is positively related to the number of units for sale. We explain these phenomena in terms of the balance of the winner's curse and the loser's curse and their di erential e ect on bidders with di erent quality of information.[+][-]