| 来源类型 | Discussion paper |
| 规范类型 | 论文 |
| 来源ID | DP7687 |
| DP7687 Keynes Meets Markowitz: The Trade-off Between Familiarity and Diversification | |
| Phelim Boyle; Tan Wang; Lorenzo Garlappi | |
| 发表日期 | 2010-02-14 |
| 出版年 | 2010 |
| 语种 | 英语 |
| 摘要 | We develop a model of portfolio choice to nest the views of Keynes - who advocates concentration in a few familiar assets - and Markowitz - who advocates diversification across assets. We rely on the concepts of ambiguity and ambiguity aversion to formalize the idea of an investor?s "familiarity" toward assets. The model shows that when an investor is equally ambiguous about all assets, then the optimal portfolio corresponds to Markowitz?s fully diversified portfolio. In contrast, when an investor exhibits different degrees of familiarity across assets, the optimal portfolio depends on (i) the relative degree of ambiguity across assets, and (ii) the standard deviation of the estimate of expected return on each asset. If the standard deviation of the expected return estimate and the difference between the ambiguity about familiar and unfamiliar assets are low, then the optimal portfolio is composed of a mix of both familiar and unfamiliar assets; moreover, an increase in correlation between assets causes an investor to increase concentration in the assets with which they are familiar (flight to familiarity). Alternatively, if the standard deviation of the expected return estimate and the difference between the ambiguity of familiar and unfamiliar assets are high, then the optimal portfolio contains only the familiar asset(s) as Keynes would have advocated. In the extreme case in which the ambiguity about all assets and the standard deviation of the estimated mean are high, then no risky asset is held (non-participation). The model also has empirically testable implications for trading behavior: in response to a change in idiosyncratic volatility, the Keynesian portfolio always exhibits more trading than the Markowitz portfolio, while the opposite is true for a change in systematic volatility. In the equilibrium version of the model with heterogeneous investors who are familiar with different assets, we find that the risk premium of stocks depends on both systematic and idiosyncratic volatility, and that the equity risk premium is significantly higher than in the standard model without ambiguity. |
| 主题 | Financial Economics |
| 关键词 | Ambiguity Diversification Portfolio choice investment Robust control |
| URL | https://cepr.org/publications/dp7687 |
| 来源智库 | Centre for Economic Policy Research (United Kingdom) |
| 资源类型 | 智库出版物 |
| 条目标识符 | http://119.78.100.153/handle/2XGU8XDN/536524 |
| 推荐引用方式 GB/T 7714 | Phelim Boyle,Tan Wang,Lorenzo Garlappi. DP7687 Keynes Meets Markowitz: The Trade-off Between Familiarity and Diversification. 2010. |
| 条目包含的文件 | 条目无相关文件。 | |||||
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