Momentum Investing: Betting That Trends Continue

Buying what is already winning

Momentum investing rests on an idea that feels almost too simple to work: stocks that have performed well recently tend to keep performing well for a while, and stocks that have lagged tend to keep lagging. Rather than asking whether a company is cheap or expensive, a pure momentum strategy asks which way the price has been moving and bets that the trend will continue. It is, in many ways, the philosophical opposite of value investing, which buys what is out of favor. Momentum buys what is already in favor, and a large body of academic research has found that, surprisingly, this has been one of the more persistent return patterns across markets and decades.

Why momentum exists

If markets were perfectly efficient, momentum should not work, prices would instantly reflect all information and past returns would say nothing about future ones. That it has worked points to human behavior. Investors tend to underreact to news at first, so good news gets priced in gradually rather than all at once, allowing a trend to build. Then, as a trend becomes obvious, others pile in, herding and chasing performance, which extends the move. Add the tendency of winning stocks to attract attention and inflows, and you have a self-reinforcing cycle that can carry prices in one direction longer than fundamentals alone would justify. Momentum is, in essence, a way of systematically harnessing those behavioral patterns.

The danger built into the strategy

Momentum's great weakness is the flip side of its strength: trends end, often violently. Because momentum buys what has risen and sells what has fallen, it is structurally exposed to sharp reversals, the moments when yesterday's winners suddenly become the hardest-hit losers. These "momentum crashes" tend to occur at market turning points, when a long-running trend abruptly reverses and the strategy is caught holding exactly the wrong stocks. Momentum can deliver strong, steady gains for long stretches and then surrender a chunk of them in a brief, brutal reversal. It is a strategy that rewards trend-following but punishes those caught at the turn.

Momentum versus value, and how they combine

Momentum and value are often described as opposites, and in a sense they are: one buys recent winners, the other buys beaten-down laggards. Yet they have historically been complementary, because they tend to work at different times, value often shines coming out of downturns when cheap stocks re-rate, while momentum excels in steady, trending markets. This is why some sophisticated strategies deliberately blend the two, using value to avoid overpaying and momentum to avoid value traps, seeking stocks that are both reasonably priced and showing improving price trends.

Reading momentum through a 13F

A 13F does not label a strategy as momentum-driven, but the behavior can leave traces. A manager that consistently adds to its best-performing positions and rotates toward whatever has been working, rather than buying into weakness, is exhibiting momentum-like behavior. The reporting lag, however, makes pure momentum hard to read from filings: by the time you see what a momentum manager bought, the trend it was riding may already have matured or reversed. The more useful lesson is conceptual, recognizing that some managers are betting on continuation rather than reversion helps you understand their holdings, and reminds you that buying recent winners is a legitimate, research-backed strategy with its own distinct risk: the reversal that eventually comes for every trend.