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© 2025, INFORMS

We provide a canonical and tractable model of a trade platform enabling buyers and sellers to transact. The platform charges a percentage fee on third-party product sales and decides whether to be "hybrid", like Amazon, by selling its own product. It thereby controls the number of differentiated products (variety) it hosts and their prices. Using the mixed market demand system, we capture interactions between monopolistically competitive sellers and a sizeable platform product. Using long-run aggregative games with free entry, we endogenize seller participation through an aggregate variable manipulated by the platform's fee. We show that a higher quality (or lower cost) of the platform's product increases its market share and the seller fee, and lowers consumer surplus. Banning hybrid mode benefits consumers. The hybrid platform might favor its product and debase third-party products if the own product advantage is sufficiently high. We also provide some tax policy implications.

Artificial intelligence systems are increasingly demonstrating their capacity to make better predictions than human experts. Yet, recent studies suggest that professionals sometimes doubt the quality of these systems and overrule machine based prescriptions. This paper explores the extent to which a decision maker (DM) supervising a machine to make high-stake decisions can properly assess whether the machine produces better recommendations. To that end, we study a set-up in which a machine performs repeated decision tasks (e.g., whether to perform a biopsy) under the DM’s supervision. Because stakes are high, the DM primarily focuses on making the best choice for the task at hand. Nonetheless, as the DM observes the correctness of the machine’s prescriptions across tasks, she updates her belief about the machine. However, the DM is subject to a so-called verification bias such that the DM verifies the machine’s correctness and updates her belief accordingly only if she ultimately decides to act on the task. In this set-up, we characterize the evolution of the DM’s belief and overruling decisions over time. We identify situations under which the DM hesitates forever whether the machine is better, i.e., she never fully ignores but regularly overrules it. Moreover, the DM sometimes wrongly believes with positive probability that the machine is better. We fully characterize the conditions under which these learning failures occur and explore how mistrusting the machine affects them. These findings provide a novel explanation for human-machine complementarity and suggest guidelines on the decision to fully adopt or reject a machine.

© 2023, INFORMS

We predict and find that regulated firms’ mandatory disclosures crowd out unregulated firms’ voluntary disclosures. Consistent with information spillovers from regulated to unregulated firms, we document that unregulated firms reduce their own disclosures in the presence of regulated firms’ disclosures. We further find that unregulated firms reduce their disclosures more the greater the strength of the regulatory information spillovers. Our findings suggest that a substitutive relationship between regulated and unregulated firms’ disclosures attenuates the effect of disclosure regulation on the market-wide information environment.

We initiate the study of naivete-based discrimination, the practice of conditioning offers on external information about consumers’ naivete. Knowing that a consumer is naive increases a monopolistic or competitive firm's willingness to generate inefficiency to exploit the consumer's mistakes, so naivete-based discrimination is not Pareto-improving, can be Pareto-damaging, and often lowers total welfare when classical preference-based discrimination does not. Moreover, the effect on total welfare depends on a hitherto unemphasized market feature: the extent to which the exploitation of naive consumers distorts trade with different types of consumers. If the distortion is homogenous across naive and sophisticated consumers, then under an arguably weak and empirically testable condition, naivete-based discrimination lowers total welfare. In contrast, if the distortion arises only for trades with sophisticated consumers, then perfect naivete-based discrimination maximizes social welfare, although imperfect discrimination often lowers welfare. And if the distortion arises only for trades with naive consumers, then naivete-based discrimination has no effect on welfare. We identify applications for each of these cases. In our primary example, a credit market with present-biased borrowers, firms lend more than socially optimal to increase the amount of interest naive borrowers unexpectedly pay, creating a homogenous distortion. The condition for naivete-based discrimination to lower welfare is then weaker than prudence.

This is an open access article.

We analyze conditions facilitating profitable deception in a simple model of a competitive retail market. Firms selling homogenous products set anticipated prices that consumers understand and additional prices that naive consumers ignore unless revealed to them by a firm, where we assume that there is a binding floor on the anticipated prices. Our main results establish that “bad" products (those with lower social surplus than an alternative) tend to be more reliably profitable than “good" products. Specifically, (1) in a market with a single socially valuable product and sufficiently many firms, a deceptive equilibrium - in which firms hide additional prices - does not exist and firms make zero profits. But perversely, (2) if the product is socially wasteful, then a profitable deceptive equilibrium always exists. Furthermore, (3) in a market with multiple products, since a superior product both diverts sophisticated consumers and renders an inferior product socially wasteful in comparison, it guarantees that firms can profitably sell the inferior product by deceiving consumers. We apply our framework to the mutual-fund and credit-card markets, arguing that it explains a number of empirical findings regarding these industries.

This is an open access article.