Advancing annuity demand theory, we present sufficient conditions for the optimal-ity of full annuitization under market completeness which are substantially less restrictive than those used by Menahem E. Yaari (1965). We examine demand with market incompleteness, finding that positive annuitization remains optimal widely, but complete annuitization does not. How uninsured medical expenses affect demand for illiquid annuities depends critically on the timing of the risk. A new set of calculations with optimal consumption trajectories very different from available annuity income streams still shows a preference for considerable annuitization, suggesting that limited annuity purchases are plausibly due to psychological or behavioral biases.
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机译：推进年金需求理论，我们提出了在市场完整性下实现完全年金最优性的充分条件，其条件远没有Menahem E. Yaari（1965）所使用的条件那样严格。我们研究了市场不完全的需求，发现积极的年金化在广泛的范围内仍然是最优的，而完全年金化则不是。未保险的医疗费用如何影响对流动性年金的需求，在很大程度上取决于风险的时机。一组最佳消费轨迹与可用年金收入流有很大不同的新计算方法仍然显示出对可观年金的偏好，这表明有限的年金购买可能是由于心理或行为偏见造成的。
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