Online Appendix to "Theoretical and Experimental Analysis of Auctions with Negative Externalities": Experimental Results for the Entire Session

Figures 1 and 2 shows the …rst drop price against values in the clock auctions for Rs and Es separately, along with the equilibrium bid functions.1 There is a mass of zero, or close to zero, bids on the part of Rs with values in the interval [0, 50] as the theory predicts: R’s with values less than or equal to 50 dropped at or before the clock auction started 28.8% of the time.2 There are also a number of drops at, or close to value (the 45 degree line), representing a failure to free ride, even at low values. Further, Rs’stage-one drops along the 45 degree line, although not the free riding the theory predicts, stand in market contrast to the frequency with which Rs drop with bids above their value This …gure excludes the 19 cases in which a bidder who dropped prior to the start of the auction and lost the SPSB auction. 2 In contrast, when an R’s value was greater than 50, he/she dropped out before the clock started less than 1% of the time. For Es with values less than or equal to 50, the overall frequency of dropping before the clock started was 12.0%. Both of these actions represent out-of-equilibrium play.