Austria's EU accession led to an increase in the number of banks participating in treasury auctions. We use structural estimates
of bidders' private values to examine the effect of increased competition on auction performance. As the results show, increased
competition reduces bidder surplus substantially, but less than reduced form estimates would suggest. A significant component
of the surplus reduction is due to more aggressive bidding. Counterfactuals establish that as competition increases, concerns
regarding auction format play a smaller role.