We provide extensions of the Bulow and Klemperer (1996) result when the seller has value for the object above the minimum value of the buyers. The result may fail. We show that the seller does better with more participation and some exclusion than the optimal exclusion of buyers of low value...

We show by an example that in first-price IPV auctions, asymmetry in bidders' valuations need not reduce the revenue compared to a benchmark symmetric model with the same amount of social surplus. Asymmetry need not reduce competition in first-price auctions.