The potential for rare economic disasters explains a lot of asset-pricing puzzles. I calibrate disaster probabilities from the twentieth century global history, especially the sharp contractions associated with World War I, the Great Depression, and World War II. The puzzles that can be explained include the high equity premium, low risk-free rate, and volatile stock returns. Another mystery that may be resolved is why expected real interest rates were low in the United States during major wars, such as World War II. The model, an extension of work by Rietz, maintains the tractable framework of a representative agent, timeadditive and isoelastic preferences, and complete markets. The results hold with i.i.d. shocks to productivity growth in a Lucas-tree type economy and also with the inclusion of capital formation. The Mehra-Prescott [1985] article on the equity risk-premium puzzle has received a great deal of attention. An article published three years later by Rietz [1988] purported to solve the puzzle by bringing in low-probability economic disasters, such as the Great Depression. I think that Rietz’s basic reasoning is correct, but the profession seems to think differently, as gauged by the continued attempts to find more and more complicated ways to resolve the equity-premium puzzle. I think the major reason for skepticism about Rietz’s argument is the belief that it depends on counterfactually high probabilities and sizes of economic disasters. Thus, a key aspect of my empirical analysis is the measurement of the frequency and sizes of the international economic disasters that occurred during the twentieth century. The three principal events are World War I, the Great Depression, and World War II, but post-World War II depressions have also been significant outside of OECD countries. My analysis of these events suggests a disaster probability of 1.5–2 percent per year with a distribution of declines in per capita GDP ranging between 15 percent and 64 percent. I construct a model of the equity premium that extends Lucas
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