We show that constraints can improve financial decision-making by disciplining behavioral biases. In financial markets, restrictions on leverage limit traders’ ability to borrow to open new positions. We demonstrate that regulation that restricts the provision of leverage to retail traders improves trading performance. By increasing the opportunity cost of postponing the realization of losses, leverage constraints improve traders’ market timing and reduce their disposition effect. We replicate these findings in two distinct experimental settings, further isolating the mechanism and demonstrating generality of the results. The interaction between constraints and behavioral biases has implications for policy and choice architecture.

Using individual credit bureau data matched with cash windfalls from fracking, we estimate that windfall recipients reduce debt-to-income by 2.4 percentage points relative to no-windfall controls. Debt repayment effects are 3 times stronger for subprime individuals than for prime individuals. Based on the timing of upfront versus continuing cash payments, debt repayment coincides with the timing of payments but not with news about future payments. These findings present a challenge for purely forward-looking models of debt. Indeed, when we incorporate a windfall shock into a forward-looking model, the model predicts an increase in debt that runs counter to our evidence of debt repayment.