The Surprising Alpha From Malkiel's Monkey and Upside-Down Strategies

摘要

Recent index literature is replete with innovations that are based on quantitative strategies and predicated on sensible investment beliefs. Empirical studies confirm that these strategies deliver economically large and statistically significant excess returns over cap-weighted market benchmarks in nearly all regions and countries, over long periods of time. In this article, the authors show that inverting these portfolio-construction algorithms does not reverse the out-performance. Indeed, the upside-down strategies often outperform the originals. This paradoxical result is driven by the phenomenon that seemingly unrelated, non-value-based strategies and their inverted counterparts often have unintended and almost unavoidable value and small-cap tilts. Even Burt Malkiel's legendary blindfolded monkey, throwing darts at the Wall Street Journal's stock page, would produce a portfolio with a substantial value- and small-cap bias that would have historically outperformed the S&P 500. The value and small-cap tilts stem from the fact that non-price-based weighting schemes sever the link between a company's share price and its weight in the portfolio. Clearly, the inverted strategy of a non-price-weighted strategy is still a non-price-weighted strategy, would consequently have a value and small-cap tilt, and would therefore have outperformed historically.