We model the feedback loop between the sales of trading advantages (e.g., data or co-location services) and traders’ endogenous participation in financial markets. Whereas a trader’s benefit from purchasing trading advantages increases with aggregate market participation, the benefit from participating decreases with other traders’ purchases of trading advantages that impose negative externalities on counterparties. In equilibrium, sellers of trading advantages (e.g., data providers or securities exchanges) may maximize their profits by prompting inefficiently low market participation and liquidity. We study the consequences of altering the market structure and show that the resulting policy prescriptions contrast sharply with standard models.

We study contracts between naive present‐biased consumers and risk‐neutral firms. We show that the welfare loss from present bias vanishes as the contracting horizon grows. This is true both when bargaining power is on the consumers' and on the firms' side, when consumers cannot commit to long‐term contracts, and when firms do not know the consumers' naiveté. However, the welfare loss from present bias does not vanish when firms do not know the consumers' present bias or when they cannot offer exclusive contracts.