Does the provision of leverage to retail traders improve market quality or facilitate socially inefficient speculation that enriches financial intermediaries? We evaluate the effects of 2010 regulations that cap leverage in the U.S. retail foreign exchange market. Using three unique data sets and a difference-in-differences approach, we document that the leverage-constraint reduces trading volume by 23%, alleviates high-leverage traders’ losses by 40%, and reduces brokerages’ operating capital by 25%. Yet, the policy does not affect the relative bid-ask prices charged by the brokerages. These results suggest the policy improves belief-neutral social welfare without reducing market liquidity.

We study the effect of subjective mortality beliefs on life‐cycle behavior. With new survey evidence, we document that survival is underestimated (overestimated) by the young (old). We calibrate a canonical life‐cycle model to elicited beliefs. Relative to calibrations using actuarial probabilities, the young undersave by 26%, and retirees draw down their assets 27% slower, while the model's fit to consumption data improves by 88%. Cross‐sectional regressions support the model's predictions: Distorted mortality beliefs correlate with savings behavior while controlling for risk preferences, cognitive, and socioeconomic factors. Overweighting the likelihood of rare events contributes to mortality belief distortions.