Like many readers of The White Coat Investor, I use a portfolio of low-cost, broadly diversified index funds. And like Jim Dahle and many Bogleheads, I incorporate a small value tilt—an intentional overweighting toward stocks that are both small in market capitalization and value-oriented in price.
This isn’t a new idea. The small value premium has been well-documented for decades. But as I revisited the research recently, I found myself asking deeper questions: Why does this premium exist? Is it still valid today? Will it persist in the future?
Here’s my hypothesis: the small value premium persists not because stock fundamentals never change but because human psychology doesn’t. We are predictably irrational in ways that consistently undervalue certain types of companies and overvalue others. As long as humans are doing the investing, the same cognitive biases will play out over and over again.
This column explores that idea. It draws from academic research, historical data, and behavioral finance—all in an effort to understand why something so well known still seems to work.
What Is a Small Value Tilt, Anyway?
Let’s start with the basics. A small value tilt means allocating a larger portion of your portfolio to small cap stocks—companies with low-market capitalization—that also have low price-to-book or price-to-earnings ratios. In other words, value stocks.
This is different from simply investing in a total market index fund, which is heavily weighted toward large cap growth companies. A small value tilt is typically implemented using targeted funds like:
- DFA US Small Value (DFSVX)
- Avantis US Small Cap Value (AVUV)
- Vanguard Small Cap Value Index (VSIAX)
While a total market fund may have only 2%-3% exposure to small value stocks, a tilted portfolio might hold 10%-40%. This deliberate deviation from the market’s default structure is based on the belief that these unloved stocks offer higher long-term returns.
What the Research Says About the Small Value Premium
The Origins: Fama and French
In the early 1990s, Eugene Fama and Kenneth French revolutionized investing theory by expanding the Capital Asset Pricing Model. They demonstrated that size (small minus large) and value (high book-to-market minus low) are independent sources of return.
Over long periods—1926-2009, for example—small cap value stocks outperformed the total market by several percentage points annually.
Periods of Outperformance (and Underperformance)
This outperformance is real—but it’s not steady.
The 1970s and early 2000s were banner decades for small value. Inflation, rising interest rates, and market rotations into more cyclical industries all favored smaller, cheaper companies.
One of the most striking rebounds came after the dot-com crash. From 2000-2006, the Russell 2000 Value Index outpaced the S&P 500 by more than 130% cumulatively. Just when many investors had declared value investing dead, small value delivered a powerful—and unexpected—counterpunch.
But small value has not always led. In the 1990s bull market, especially the late 1990s during the tech boom, growth dominated, and small value dramatically underperformed. Similarly, from 2009 until now, small value has significantly lagged large cap growth, particularly in technology-driven sectors. Throughout nearly all of my tenure as a serious investor since completing fellowship just over a decade ago, I have maintained a small value tilt. Yet during this period, it has consistently underperformed large cap growth.
These alternating stretches illustrate a key truth: the small value premium may be real over the long run, but investors need to endure long, frustrating droughts to realize it.
More information here:
Which Small Cap Value Funds Are Best for You?
Rick Ferri vs. Paul Merriman on Factor Investing
Does the Small Value Tilt Still Work Today?
Some argue the small value premium has been arbitraged away or that it merely reflects higher risk. That’s possible but incomplete. Yes, the fundamentals evolve. Markets get more efficient. Information spreads faster. But what doesn’t change is human behavior.
- Investors still chase hype.
- They still overweight recent performance.
- They still panic at losses and crave social validation.
And because those behaviors are deeply rooted in psychology, they’re not going away, regardless of how efficient or algorithmic the stock market becomes.
While valuation gaps and structural inefficiencies may come and go, the psychological forces that drive mispricing are remarkably durable. Humans consistently chase glamour and growth stories, overlooking smaller, cheaper, and less exciting companies—leaving small value stocks systematically underpriced. That’s why I believe the small value premium is likely to continue—not because the market is broken but because humans are.
The Psychology Behind the Premium
Markets aren’t just moved by math. They’re moved by emotion. Nobel Prize-winning economist Robert Shiller put it more elegantly:
“The stock market is more driven by stories and psychology than by fundamentals.”
That may sound surprising in a world full of spreadsheets and earnings models, but it reflects reality. As behavioral finance experts like Daniel Kahneman, Richard Thaler, and Meir Statman have shown, investor behavior is shaped far more by emotion, social influence, and flawed mental shortcuts than by pure logic.
And that’s exactly where the small value premium takes root.
#1 Neglect and Inattention
Small value stocks are boring. They don’t trend on CNBC or Reddit. They’re not the next Tesla or Nvidia. As a result, they’re often ignored by analysts, investors, and even fund managers. This lack of attention creates inefficiency. Like undervalued real estate in a forgotten part of town, small value stocks can be quietly mispriced for years.
Ambiguity aversion also plays a role. Small value companies often operate in obscure sectors with limited analyst coverage or inconsistent earnings reports. Investors shy away not necessarily because the risks are higher but because they feel less certain about what they're getting.
#2 The Glamour Trap
We’re drawn to exciting narratives—disruption, innovation, exponential growth. Growth stocks come with stories we want to believe. This is where several powerful biases converge:
- The representativeness heuristic leads us to assume that exciting companies must also be good investments. If a stock “looks like a winner,” we treat it as one—even if the price is inflated.
- The affect heuristic causes us to judge investments based on how they make us feel rather than their fundamentals.
- Apophenia nudges us to see meaningful patterns in noisy or random data—like believing a growth stock is “on a roll” after a few good quarters.
- And thanks to the availability heuristic, stories of successful growth stocks dominate headlines and social media, making them feel far more common and reliable than they really are.
Meanwhile, small value stocks—the “ugly ducklings”—lack narrative appeal and media attention. But that’s often where the long-term opportunity lies.
#3 The Focusing Illusion
As Daniel Kahneman famously said, “Nothing in life is as important as you think it is while you are thinking about it.”
This is the focusing illusion in action. When the media and social networks fixate on tech and growth stocks, our brains overweight their importance. We become convinced we must own what everyone is talking about—even if it’s wildly overvalued. By contrast, small value stocks fade into the background, reinforcing the neglect that helps create the premium in the first place.
#4 Loss Aversion and Recency Bias
Behavioral research shows we feel losses about twice as intensely as we feel gains. When small value underperforms—as it did for much of the last decade—investors bail.
We’re also wired with recency bias, the belief that recent trends will continue indefinitely. After years of growth stock dominance, many investors declared value investing dead—just in time for the cycle to turn.
#5 Overconfidence and Naïve Extrapolation
We tend to overestimate our ability to pick winners and forecast the future. When we see a stock rise, we assume it will keep rising. This is a form of naïve extrapolation that leads us to chase performance, even when fundamentals don’t support it.
#6 Social Comparison, Herding, and FOMO
This may be the most powerful psychological force of all.
When your colleague brags about doubling their money on Nvidia, your small value tilt can feel embarrassing. That’s social comparison in action. We don’t just want to do well; we want to do better than others.
Enter herding and social proof. When we see others piling into hot growth stocks, we assume they must know something we don’t. It feels safe to follow the crowd. And thanks to FOMO (fear of missing out), we abandon our strategy just when it’s poised to rebound. Overreaction bias compounds this problem. Investors tend to respond too strongly to both good and bad news, especially in sectors perceived as volatile. This leads to exaggerated price drops in small value stocks, creating even more room for long-term mispricing.
Why It Still Works: Because It’s Hard
If the small value premium is so well-known, why hasn’t it disappeared? Because earning it is emotionally grueling. To benefit from the premium, you have to:
- Stay invested during years—sometimes a decade—of underperformance
- Rebalance into the very funds that feel like dead weight
- Ignore headlines and resist chasing the hot hand
Few investors can do that. And that’s why the premium persists.
More information here:
Value Tilt – Don’t Give Up on Your Small Cap Value Strategy
Why the Russell Small Cap Value Index Sucks (and How to Ditch It)
How to Implement a Small Value Tilt
Interested in tilting your own portfolio? It doesn’t have to be complicated, and there’s no single “correct” percentage.
Experts who recommend a small value tilt typically suggest allocating between 10%-40% of your US stock exposure to small cap value funds, depending on your risk tolerance, investment horizon, and conviction in the premium. My personal portfolio lands at 25% of my US equity exposure allocated to small value. That’s the level I’ve found to be psychologically sustainable and financially compelling. But reasonable investors may choose anywhere within that range—and still capture most of the behavioral benefit.
Here are a few widely used small value funds to consider:
- Avantis US Small Cap Value (AVUV)
- Vanguard Small Cap Value Index (VSIAX)
- DFA US Small Value (DFSVX)
The key isn’t finding a magic number. It’s committing to a strategy you’ll actually stick with, especially when small value underperforms. Rebalance regularly. Stay consistent. And remember, the hardest part isn’t the math; it’s the mindset.
Behavioral Discipline Is the Real Alpha
The small value tilt has delivered results for nearly a century. Traditional explanations like risk and structural inefficiency still matter. Yet it’s important to note that over the past 16 years, small value has not consistently outperformed, reminding investors that the premium comes in long, uneven cycles. But in 2025, the most compelling reason to believe in the premium is this:
It’s rooted in human psychology—and human psychology isn’t changing anytime soon.
Investors remain predictably irrational. They chase performance, follow the crowd, avoid pain, crave excitement, and forget that markets move in cycles. These behaviors create persistent mispricing. Small value stocks are simply the ones most often left behind.
That’s why I tilt my portfolio toward them. Not because I think I’m smarter than the market, but because I believe I can be more emotionally disciplined than most of the market.
Success in investing isn’t about being brilliant. It’s about staying brave when the story doesn’t feel good. That’s behavioral alpha. That’s why the small value tilt still matters.
Does your portfolio have a small value tilt? Have you been satisfied with it? If not, do you plan to continue it? If you don't have small value, are you considering adding some?