At a minimum, we hope that our research will encourage future theorizing and econometric modelingoftherichdynamicsinspectrumauctions. Inouropinion,thesedynamicsareavery important, if puzzling, component of bidder behavior and have not been adequately explored in the literature. Improved auction design, including preventing tacit collusion, could beneÖt greatly from an enhanced understanding of the dynamics of bidder behavior.