We investigate the performance of non-linear return prediction models in the high complexity regime, i.e., when the number of model parameters exceeds the number of observations. We document a "virtue of complexity" in all asset classes that we study (US equities, international equities, bonds,...

Contrary to conventional wisdom in nance, return prediction R2 and optimal portfolio Sharpe ratio generally increase with model parameterization, even when minimal regularization is used. We theoretically characterize the behavior of return prediction models in the high complexity regime, i.e....

The lion’s share of hidden Markov models (HMMs) /Markov regime switching models considered in economic research incorporates a comparably small number of states. The popularity of models with mostly two or three states principally results from their good interpretability: often regime...