The current market malaise may keep some investors on the sidelines. The benefits of diversification may not seem as appealing in situations where the constituent investments are likely to lose money. Yet we will see, using relatively simple math, that diversification maintained by rebalancing...

We study a dynamic mean-variance portfolio optimization problem under the reinforcement learning framework, where an entropy regularizer is introduced to induce exploration. Due to the time-inconsistency involved in a mean-variance criterion, we aim to learn an equilibrium strategy. Under an...

A mechanical rebalancing strategy, such as a monthly or quarterly reallocation towards fixed portfolio weights, is an active strategy. Winning asset classes are sold and losers are bought. During crises, when markets are often trending, this can lead to substantially larger drawdowns than a...

This paper characterizes the optimal risk-taking strategies of mutual fund managers competing in multi-period winner-take-all tournaments. With competition among mutual funds, every fund begins by taking maximum risk. In the final period, all funds continue to take maximum risk except possibly...