Hugh H. Kim, Raimond Maurer, Olivia S. Mitchell. 2013. Time is money: life circle rational inertia and delegation of investment management. Working Paper 19732. National Bureau of Economic Research

http://www.nber.org/papers/w19732

Abstract: :We investigate the theoretical impact of including two empirically-grounded insights in a dynamic life cycle portfolio choice model. The first is to recognize that investors incur opportunity costs in terms of current and future human capital accumulation when managing their own financial wealth, particularly if human capital is acquired via learning by doing. The second is that we incorporate age-varying efficiency patterns in financial decision making. Both enhancements produce inactivity in portfolio adjustment patterns consistent with empirical evidence. We also analyze individuals’ optimal choice between self-managing their wealth versus delegating the task to a financial advisor. Delegation proves most valuable to the young and the old. Our calibrated model quantifies welfare gains from including investment time and money costs, as well as delegation, in a life cycle setting.

摘要：我们调查了将两类以实证为基础的发现纳入动态生命周期投资组合模型的理论影响。第一个发现是投资者管理财富时，面对现在和未来的人力资本积累尤其是那些从实践中学习而实现的人力资本，存在着机会成本问题。第二个发现是我们将随年龄变化的效率模式与金融决策结合在一起。这两类修正都在与经验数据一致的投资组合调整模式中产生了稳定性。我们也研究了个人在亲自管理财富和委托金融投资人代管财富两者之间的选择。结果发现代管财富对年轻人和老人最有价值。我们的标准模型通过将投资时间、金钱成本、委托代管纳入生命周期的背景，来衡量福利收益。

数据来源：过去的实证研究

研究方法：数学推理

Conclusion:This paper develops and simulates a life cycle model to illustrate optimal portfolio management methods selected by finitely-lived investors who face portfolio management cost sand an age-dependent inefficiency pattern for financial decision-making. Using a reasonable set of parameters, our model replicates observed patterns of portfolio inertia across age groups.

Investors who can accumulate job-specific knowledge by working tend to devote less time to managing their money when they are young. Middle-aged both have more assets to invest and suffer less from the opportunity costs of self-managing their assets, though many still elect inertia. Declining decision-making efficiency later in life prompts many older investors to select portfolio inertia. When investors can delegate the portfolio management task to a financial advisor, this enables many to avoid portfolio inertia. In general, the model predicts that older investors will find financial advisors most attractive. Finally, we find rather substantial welfare gains resulting from having a delegation option.

Our findings are relevant to a variety of stakeholders including individual investors, financial advisors, retirement plan sponsors, and policymakers. Those who will value financial advisory services the most are the young and the older age groups, so making such services available can greatly enhance their well-being. Also of interest is the prediction that advisors will find that some middle-aged clients will wish to continue self-managing their own financial assets, even when a delegation option is available. Policymakers may also wish to consider the potential positive welfare gains of improving investor access to financial advisory services. In an environment where financial advisors with fiduciary responsibility can help investors manage their financial wealth optimally, this will enable more people to accrue job-specific skills, thus contributing to the economy as a whole.

结论：这篇文章发展并模拟了一个生命周期模型来描述了生命有限的投资者所选择的最佳投资组合管理方法，他们所面对的则是组合管理的成本和与年龄相关的金融决策的效率模式。使用一系列合理的参数，我们的模型复制了不同年龄群体的可观察到的投资组合惯性模式。可以通过工作积累特殊知识的投资者在他们年轻的时候，倾向于投入更少的时间来管理他们的金钱。尽管许多人作出惯性选择，中等年龄的群体既有更多的财产用于投资，又更少地遭受亲自管理资产的机会成本的困扰。随着生命晚期决策效率的下降，许多老年投资者选择惯性的投资组合。当投资者可以把资产组合管理委托给金融顾问时，他们就可以避免惯性投资组合。总的来说，这个模型预测老年投资者会认为金融顾问更具有吸引力。最后，我们发现选择委托可以带来相当大的福利回报。

我们的发现与一系列利益相关方有关，包括个人投资者、金融顾问、退休计划赞助商以及政策制定者。认为金融顾问最有价值的人群中大多是老年人和少年人，因此让这类服务更容易获得可以巨大地改善他们的福利。另外一个有趣的预测是一部分中年顾客希望继续亲自管理他们的金融资产，即使委托选择是容易获得的。政策制定者也希望考虑能够获得金融顾问服务的投资者所获得的潜在福利收益。在一个负有受托责任的金融顾问可以最恰当地帮助投资者管理资产的环境中，这使得更多人能积累特殊的工作技能，进而从整体上使经济受益。

（By 苏小舟）