Auctions with both common-value and private-value bidders

► This note analyzes auctions with two different types of bidders: some with private values (consumers) and some with common values (investors). ► The monotone pure-strategy equilibrium exists and the characterizations of the equilibrium are provided. ► Efficiency is analyzed in large society: the probability of having efficiency loss converges to a positive number, while the expected efficiency loss and expected profit loss shrink to zero.