EXPRESS: Sellers’ Peer Comparison under Uncertainty in Online Marketplace

How will peer pressure among sellers affect their operations in an online marketplace? Motivated by online platforms’ marketplace designs that prompt sellers to compare their performances, in this paper, we develop and study a price competition model in which sellers account for both profits and peer comparison outcomes. In our model, two sellers offer substitutable products, and each of them sets a price ex ante to maximize their expected total utility, which is the sum of one’s profit and the payoff from peer comparison. In particular, peer comparison takes place ex post based on sellers’ realized sales. It results in a penalty for one’s underperformance (i.e., sellers are behind-averse) or a reward for outperformance (i.e., sellers are ahead-seeking) relative to the other seller. Contrary to what extant research on social comparison would predict, we find that peer comparison is not always pro-competitive. Indeed, while the behind-aversion aspect of peer comparison fosters competition, the ahead-seeking aspect can be anti-competitive when the market uncertainty is sufficiently large. This is because market uncertainty causes a greater variation in sellers’ performance disparity ex post ( uncertainty effect ), which can have a more salient impact on sellers than the expectation of their performance gap ( comparison effect ); While sellers’ behind-aversion further aggravates the uncertainty effect and encourages them to take more aggressive actions, their ahead-seeking counterbalances the tension by absorbing part of it into the comparison effect and moderating the marginal disutility of lagging behind. Overall, we find that peer comparison can intensify sellers’ price competition, which lowers the expected profits and utilities for both sellers, benefits the consumers, and reduces the hosting platform’s profit. Our main insights are robust in a number of extensions, including general demand specifications, seller asymmetry, sellers’ misperceptions of market uncertainties, and consumers’ reference-dependent decision-making. They highlight the importance of sellers’ behavioral regularities in online platforms’ daily operations and shed light on marketplace designs regarding algorithmic transparency, information sharing, and so forth.