Optimal Leveraged Portfolio Selection Under Quasi-Elastic Market Impact

Abstract

Dangers of Ignoring Market Friction When Leveraging Financial PortfoliosPortfolio leveraging is a standard industry practice to target higher fund returns, for example, in risk parity asset allocation. However, the existing models of optimal bet sizing fail to integrate analytically the impact on leveraged portfolio selection resulting from market liquidity issues. The paper “Optimal Leveraged Portfolio Selection Under Quasi-Elastic Market Impact” considers a market in which both temporary and permanent impact on trading prices are present with the former impact being sufficiently large relative to the latter. Our analytical conclusions, supported by a case study that uses even relatively more liquid U.S. exchange-traded fund assets, demonstrate that fund managers are ill advised to ignore market friction when leveraging to achieve target higher returns. Not only risk-adjusted returns significantly deteriorate, but also those losses become steeper when setting higher targets requiring increased levels of leverage. Moreover, leverage-constrained and less risk-averse investors ignoring liquidity costs ex ante face the most losses in expected utility ex post.