Pricing algorithms are increasingly replacing human decision making in real marketplaces. To inform the competition policy debate on possible consequences, we run experiments with pricing algorithms powered by Artificial Intelligence in controlled environments (computer simulations).In...

In a payment card association such as Visa, each time a consumer pays by card, the bank of the merchant (acquirer) pays an interchange fee (IF) to the bank of the cardholder (issuer) to carry out the transaction. This paper studies the determinants of socially and privately optimal IFs in a card...

Payment card networks, such as Visa, require merchants' banks to pay substantial "interchange" fees to cardholders' banks, on a per transaction basis. This paper shows that a network's profit-maximizing fee induces an inefficient price structure, over-subsidizing card usage and over-taxing...

We analyze the classic problem of sustaining trust when cheating and leaving trading partners is easy, and outside enforcement is difficult. We construct equilibria where individuals are loyal to smaller groups – communities – that allow repeated interaction. Hierarchies provide incentives...