论文标题
递归卫星投资帐户的过度过度过度
Recursive Overbetting of a Satellite Investment Account
论文作者
论文摘要
本文建立了半静态凯利博彩和最佳投资的核心 - 卫星模型。我们研究了一个储蓄者的问题,其核心投资组合由未杠杆(1倍)退休计划组成,无法获得保证金债务。但是,代理商有一个卫星投资帐户,可求助于大量但无限的杠杆作用;因此,我们研究了卫星齿轮比率的最佳控制器。在很短的时间范围内,最好的政策是过度支撑卫星,因此,高层目标是将总β提高到最佳水平。相比之下,在无限的地平线上,正确的行为是忽略核心并优化卫星的指数增长率,无论如何,这将在整个债券中占主导地位。在严格介于零和无穷大之间,最佳策略并不是那么简单:复合资金的瞬时增长率与卫星本身的瞬时增长率之间存在着关键的权衡,而卫星本身的瞬时增长速度会遭受持续的波动性。因此,要求一项非常敏锐的政策,因为卫星中的任何损失都会限制代理商在延续问题中获得杠杆的访问。我们表征了最佳反馈控制器,并通过递归递归和向后求解相应的HJB方程来认真对其进行计算。然后将该解决方案与最佳的开环控制器进行比较,尽管其相对简单性,但在实际情况下,该解决方案的性能有望相似。
This paper builds a core-satellite model of semi-static Kelly betting and log-optimal investment. We study the problem of a saver whose core portfolio consists in unlevered (1x) retirement plans with no access to margin debt. However, the agent has a satellite investment account with recourse to significant, but not unlimited, leverage; accordingly, we study optimal controllers for the satellite gearing ratio. On a very short time horizon, the best policy is to overbet the satellite, whereby the overriding objective is to raise the aggregate beta toward a growth-optimal level. On an infinite horizon, by contrast, the correct behavior is to blithely ignore the core and optimize the exponential growth rate of the satellite, which will anyways come to dominate the entire bankroll in the limit. For time horizons strictly between zero and infinity, the optimal strategy is not so simple: there is a key trade-off between the instantaneous growth rate of the composite bankroll, and that of the satellite itself, which suffers ongoing volatility drag from the overbetting. Thus, a very perspicacious policy is called for, since any losses in the satellite will constrain the agent's access to leverage in the continuation problem. We characterize the optimal feedback controller, and compute it in earnest by solving the corresponding HJB equation recursively and backward in time. This solution is then compared to the best open-loop controller, which, in spite of its relative simplicity, is expected to perform similarly in practical situations.