The catch is that the wave can break violently. In this guide you will learn what momentum investing is, why it works, how to build a rules-based version, what a real momentum fund looks like today, and the crash risk that decides whether you can stick with it.
The iShares MTUM fund page on 28 October 2026: a 0.15% fee, 125 holdings and about $18.7 billion in assets.
What Is Momentum Investing?
Momentum investing is a strategy that buys assets with strong recent performance and avoids or sells assets with weak recent performance. It rests on a measurable pattern: stocks that beat the market over the past 3 to 12 months tend to keep beating it for a while afterwards.
The landmark study is Jegadeesh and Titman (1993), published in the Journal of Finance, which showed that buying past winners and selling past losers earned an average excess return of roughly 1% per month. Researchers later added momentum as a standard factor next to value and size, so it now appears in most professional factor models.
Two flavors matter. Cross-sectional momentum ranks stocks against each other and buys the top group. Time-series momentum looks at one asset against its own history and holds it only while its trend is positive. The first picks winners, the second decides when to be invested at all.
Why Momentum Investing Matters
Most investors hold a market-cap index fund and stop there, which is a sound default. Momentum matters because it behaves differently from the other common return drivers. Value stocks are cheap relative to fundamentals, while momentum stocks are usually expensive and already popular. Combining them can smooth the ride.
The pattern appears across regions and asset classes, which is why academics treat it as more than a data accident. Two explanations dominate. The behavioral view says investors underreact to news, so prices adjust slowly and trends persist. The risk view says momentum earns a premium because it carries a rare but brutal crash risk that few people can stomach.
$18.69 billion sits in a single U.S. momentum ETF today, so this is no longer a niche academic idea. Real money follows it, and that popularity is itself something to monitor.
Momentum also pairs well with disciplined risk work. If you track maximum drawdown and downside risk with the Sortino ratio, you already have the measurements you need to judge whether a momentum strategy fits your tolerance.
How to Build a Momentum Strategy: A Rules-Based Framework
You can buy a ready-made fund or run your own rules. Either way, the process has the same skeleton. Write the rules down before you invest, because momentum is emotionally hard to follow in a drawdown.
Step 1: Pick Your Universe
Choose a liquid, well-defined group of stocks such as a broad large-cap index. A large universe gives the ranking more to work with, and liquid names keep trading costs low. Avoid tiny, thinly traded stocks where momentum looks great on paper and fails in practice.
Step 2: Measure Momentum With 12-1
The standard signal is the 12-1 return: the stock's total return over the past 12 months, skipping the most recent month. The skipped month matters because very recent winners often reverse briefly, a short-term effect that would contaminate the signal.
Step 3: Rank and Select
Rank every stock by its 12-1 return and keep the top 10% to 20%. Fewer names means more concentration and more risk. Many index providers also adjust the ranking for volatility so that a stock with a smooth climb scores higher than one with a wild one.
Step 4: Weight and Cap Positions
Equal weighting is simple. Weighting by market cap keeps costs down. Whichever you pick, cap any single position so one fashionable stock cannot dominate. If you size positions by conviction, the Kelly criterion for position sizing gives a principled upper limit.
Step 5: Rebalance on a Schedule
Momentum signals decay, so the portfolio needs refreshing. Most funds rebalance every three to six months. Rebalancing more often raises turnover and taxes, while rebalancing less often lets the signal go stale. The general logic mirrors any portfolio rebalancing strategy, only with a faster clock.
Step 6: Add a Crash Guard
Because crashes are the main danger, add a rule that cuts exposure when the market has fallen sharply and volatility is high. A simple version moves part of the portfolio to cash when the broad market sits below its 200-day average. It will cost you some return in calm years, which is the price of insurance.
The NBER working paper that documents how and when momentum crashes, captured 28 October 2026.
Real Examples: A Momentum Fund and Two Famous Crashes
The largest U.S. momentum ETF is the iShares MSCI USA Momentum Factor ETF (MTUM). It launched on April 16, 2013 and tracks the MSCI USA Momentum SR Variant Index. Here is what the fund page showed in late October 2026.
MTUM snapshot (BlackRock, 27 to 28 October 2026)
16.48% annualized over ten years sounds spectacular, yet the 1.27 beta tells the other half of the story. The fund moves about 27% more than the market on average, so part of that return is simply extra market risk.
The crashes are where momentum earns its reputation. Kent Daniel and Tobias Moskowitz studied them in their Momentum Crashes paper and found they cluster after market declines, when volatility is high and the market rebounds sharply.
Momentum crash episodes (Daniel and Moskowitz, NBER 2014)
-74.36% in a single month, August 1932, is the worst momentum month in their sample. The pattern repeated in 2009: from March to May, the loser decile rose 163% while the winner decile gained only 8%. Beaten-down stocks behave like call options, and when the market bounces they explode upward.
This is the same wave metaphor in action. The wave carries you for years, then a market reversal breaks it, and the stocks you shorted or avoided leap past the ones you own.
There is also a practical lesson in the timing. Both crash windows began after severe market declines, which means the danger is highest when you feel most tempted to buy the rebound. Losers that were sold off hardest tend to snap back first, and a portfolio tilted toward past winners misses that bounce completely.
Daniel and Moskowitz also tested a dynamic version that scales exposure up and down using forecasts of momentum's own volatility. According to the abstract, it roughly doubles the alpha and Sharpe ratio of a static momentum strategy. The takeaway for ordinary investors is modest but useful: reducing exposure when volatility is elevated can improve results, and you can apply the same logic with a simple volatility rule.
If you want to see how fast leveraged products magnify this problem, read about volatility decay in leveraged ETFs. Pairing leverage with momentum is how small drawdowns turn into permanent losses.
Your next step: pick one rule from the framework above, write it down, and test it on paper for a quarter before committing real money. A written rule beats a good feeling every time.
Common Mistakes With Momentum Investing
Mistake 1: Ignoring Crash Risk
Backtests that stop at the average return hide the pain. A strategy that earns 1% per month on average can still lose half its value in a quarter. Size your position so that a 50% drop in the momentum sleeve would not change your life, and read the expected shortfall guide to see how professionals measure that tail.
Mistake 2: Chasing the Most Recent Month
Using the last month of returns in your signal feeds short-term reversal into a strategy built for longer trends. That is why the standard signal skips the latest month. If your screen ranks by one-month gains, you are running a different and weaker strategy.
Mistake 3: Overtrading and Forgetting Costs
Momentum needs turnover, and turnover costs money through spreads, commissions and taxes. A fund fee of 0.15% looks cheap, but a personal portfolio that trades weekly can lose far more to friction. Rebalance on a fixed calendar and ignore the noise between dates.
Mistake 4: Buying After a Long, Crowded Run
Popularity attracts money, and crowded trades unwind fast. When a momentum fund already holds $18.69 billion, many holders share the same positions. Check what the fund actually owns before assuming it diversifies your existing stocks, and compare it with the correlation lessons in this guide.
Mistake 5: Abandoning the Strategy at the Bottom
The most common failure is behavioral. Investors buy after a great year and sell during the crash, which locks in the worst of both. Write your rules, including your crash guard, before you invest and follow them without edits.
Frequently Asked Questions
Does momentum investing still work?
The long record is positive, and funds like MTUM have posted strong multi-year returns. But it works in stretches and fails in sharp bursts, so judge it over a full cycle and not a single year.
Is momentum investing the same as trend following?
They are close cousins. Momentum investing usually ranks stocks against each other, while trend following looks at one asset's own price trend. Both assume that recent performance carries information about the near future.
What is the best momentum investing strategy for beginners?
A low-cost momentum ETF held as a small slice of a diversified portfolio is the simplest route. It removes the work of ranking and rebalancing, and a small allocation limits the damage if a crash arrives.
How much of my portfolio should be in momentum?
There is no universal number. Many investors keep it to 10% to 20% of their equity holdings, so that a crash hurts without derailing long-term goals. Your own risk tolerance and time horizon decide the rest.
How does momentum compare with value investing?
They often move in opposite directions. In the Fama/French data for September 2026, the value factor (HML) fell 1.55% while it had gained 12.15% over the previous 12 months. Holding both tends to reduce the swings of either alone.
Fama/French factor returns from Kenneth French's data library, September 2026 release.
Key Takeaways
- Momentum means buying recent winners and avoiding recent losers, and it has earned roughly 1% per month on average in classic studies.
- The standard signal is the 12-1 return, which skips the latest month to avoid short-term reversal.
- Crashes are the real cost: momentum lost 74.36% in August 1932 and over 40% in each of March and April 2009.
- A fund such as MTUM charges 0.15% and holds 125 stocks, but its beta of 1.27 means it amplifies market moves.
- Rebalance on a fixed schedule and add a crash guard before you invest, not after.
- Treat momentum as one slice of a diversified portfolio, and size it so a crash will not force you to sell.
Back to the surfer: the skill is not in finding the wave, it is in knowing when to get off. Momentum rewards patience on the way up and discipline on the way down.
What to Watch Next
- > Does MTUM's 1.27 beta rise or fall after its next index rebalance?
- > Does value (HML) keep falling after a strong 12-month run of 12.15%?
- > Do the MTUM forward split and share trading from November 5, 2026 change trading volume?
- > Does market volatility spike after a long decline, the setup that preceded past momentum crashes?
References
This article is for education only and is not financial advice. Past performance does not guarantee future results.