Treasury actions: The Spanish format

The Spanish Treasury is the only Treasury in the world that uses a hybrid system of discriminatory and uniform price auctions to sell government debt: winning bidders pay their bid price for each unit if this is lower than the weighted average price of winning bids, and pay the weighted average price of winning bids otherwise. Following Gordy (1996), we model the Spanish auction as a common value auction of multiple units with private information, allowing for multiple bids. Simulations show that bidders use bid spread to hedge against both uncertainty and the winner's curse, and that the expected seller's revenue is higher in the Spanish than in the discriminatory auction in a number of cases.