主题：In Search of Preference Shock Risks: Evidence from Longevity Risks and Momentum Profits（探寻时间偏好风险：基于人寿风险和惯性策略的证据）
Time-preference shocks affect agents' preferences for assets with different durations. We consider longevity risk as the sources of time-preference shocks and model it in the recursive preferences setting. This implies a consumption-based three-factor model, including longevity risk, consumption growth rate, and the market portfolio, where longevity has a negative price of risk. Empirically, this model explains many well-known cross-sectional portfolios. Notably, we find that longevity risk and the momentum factor share a common business cycle component, i.e., short-run consumption risks. Prior winners (losers) provide hedging against mortality (longevity) risk and thus have higher (lower) expected returns, because winners have shorter equity durations than losers. Time-varying longevity risk captures most momentum profits over time, including the large momentum crashes observed in the data.