We construct a panel of eBay seller histories and examine the importance of eBay's reputation mechanism. We find that, when a seller first receives negative feedback, his weekly sales rate drops from a positive 5% to a negative 8%; subsequent negative feedback ratings arrive 25% more rapidly than the first one and don't have nearly as much impact as the first one. We also find that a seller is more likely to exit the lower his reputation is; and that, just before exiting, sellers receive more negative feedback than their lifetime average.