I study the impact of bid credits on simultaneous ascending auctions in a model where bidders potentially have complementary values. Although bid credits can lead to a more equitable distribution of items, I find an additional unintended consequence: bidders without credits are more exposed to winning a less desirable set of items and will drop out of the auction sooner when their competitors have credits. Calibrating the model to data from the Federal Communication Commission's sale of licenses in the 700 MHz guard bands, I find exposure reduced average non-credited dropout values by 5.7 percent but did not decrease revenues. (C) 2022 Elsevier Inc. All rights reserved.
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