Revealing transactions data to third parties: Implications of privacy regimes for welfare in online markets

We examine the effects of privacy policies regarding transactions (e.g., price/quantity) data on online shopping platforms. Disclosure of transactions data induces consumer signaling behavior that affects merchant pricing decisions and the welfare of platform participants. A profit‐maximizing platform prefers the disclosure policy that maximizes total welfare. Although this policy benefits sophisticated consumers, it harms unsophisticated (myopic) consumers. Consequently, the welfare effects of alternative privacy policies, data breaches, deceptive privacy policies, and opt‐in/opt‐out requirements can differ sharply, depending on the level of consumer sophistication and on other factors such as the prevailing status quo.