Momentum has existed for hundreds of years and has persisted for two decades post discovery. This sort of staying power in capital markets full of hungry arbitrageurs is always the mark of human psychology.
Many experts consider momentum to not just be a factor but THE factor. Fama and French don’t mince words, “The premier market anomaly is momentum. Stocks with low returns over the past year tend to have low returns for the next few months, and stocks with high past returns tend to have high future returns.” As James O’Shaughnessy says, “of all the beliefs on Wall Street, price momentum makes efficient market theorists howl the loudest.” In a perfect world, there would be no good reason to pay more for a business today than yesterday simply because of positive price action. But this isn’t a perfect world, it’s a world ruled by human behaviour and thus exhibits all of the attendant quirks.
Like peanut butter and chocolate, momentum and value are wonderful on their own, but even better together. Cliff Asness says it best in his piece, A New Core Equity Paradigm:
“Value and momentum remain the two strongest findings of academic and practitioner research of the last 30 years. While academics continually identify new market anomalies, which purport to offer significant risk-adjusted excess returns, and the Street routinely spins new stories to sell them, value and momentum stand head-and-shoulders above the rest-no other styles have performed so well, for so long, and in so many places. Both value and momentum have long histories of providing attractive returns, have performed well across markets and across asset classes, and have persisted for decades after their discoveries. Importantly, the two strategies perform even better when combined.” Value and quality work, independently and in concert, precisely because they exhibit the three hallmarks of an investable factor: empirically evidence, theoretical soundness and a behavioral foundation.