Herd Mentality Investing: Why “Be a Contrarian” Is the Wrong Fix
Half of Gen Z investors in the U.S. say they’ve made at least one investment purely out of fear of missing out, according to a 2023 FINRA Foundation and CFA Institute study. That’s herd mentality investing in one number: buying something because everyone around you is buying it. This post explains why the standard cure (“be fearful when others are greedy,” “go against the crowd”) doesn’t work for most people, what the data supports instead, and the specific situations where following the herd is the smartest move you can make.
The Popular Advice on Herd Mentality Investing: “Just Be a Contrarian”
Open almost any article about herd behavior in markets and you’ll get the same prescription. The crowd is emotional, the crowd buys high and sells low, so do the opposite. Warren Buffett’s line about being “fearful when others are greedy, and greedy when others are fearful” gets quoted so often it has become the default answer to the problem.
The diagnosis behind that advice is real. Social conformity is one of the most replicated findings in psychology. In Solomon Asch’s classic line-judgment experiments in the early 1950s, participants surrounded by actors giving an obviously wrong answer went along with the group on roughly a third of the critical trials, and about three-quarters of participants conformed at least once. Those were lines on a card with a clear right answer. Markets, where nobody knows the right answer, give social proof even more room to work.
The investing data backs the diagnosis too. In their 2008 paper “All That Glitters,” published in the Review of Financial Studies, Brad Barber and Terrance Odean studied trading records from three brokerages covering hundreds of thousands of individual accounts. On the days when a stock had its highest abnormal trading volume, individual investors at a large discount broker placed nearly twice as many buy orders as sell orders, a buy-sell imbalance of about +29.5%. On days with news coverage, the imbalance at a large retail broker was +16.2%, versus −1.8% on days without news. Individuals buy what’s getting attention, and attention is what the herd generates.
So the problem is real. The question is whether “be a contrarian” is the fix.
Why the Contrarian Fix Doesn’t Work for Most Investors
Here’s the uncomfortable part: contrarianism is just another market-timing strategy, and market timing is precisely what the herd gets wrong in the first place.
1. Contrarians still have to time the turn
“Buy when others are fearful” sounds simple until you’re in the middle of it. Fear doesn’t come with a label that says “bottom.” Markets that fall 20% can fall another 20%. A contrarian who bought tech stocks after the first leg down in 2000 or bank stocks in early 2008 was “going against the herd” and still got crushed. Being early and being wrong look identical for months or years.
The behavioral research on individual investors isn’t kind to anyone trying to make these calls. Barber and Odean’s broader body of work found that the households that traded most actively earned meaningfully lower net returns than those who traded least. Swapping “buy what’s hot” for “buy what’s hated” doesn’t change the underlying habit of trading on a story. It just reverses the story. Our breakdown of overconfidence bias in investing covers why most of us rate our own timing ability far higher than the record justifies.
2. “Going against the crowd” can itself become a crowd
Contrarian takes are now a content genre. Plenty of social media accounts build an audience by predicting crashes, mocking whatever is popular, or pitching the “unloved” sector of the month. Following a contrarian influencer is still herding. You’ve just picked a smaller herd with a better-sounding slogan.
The same FINRA Foundation and CFA Institute study found that 48% of Gen Z investors learn about investing primarily through social media, and YouTube was the most-used online resource at 60%. Whether the feed says “everyone’s buying” or “everyone’s wrong,” the decision is still being outsourced to whoever is loudest.
3. The real damage comes from timing, not direction
The best measure of how much herd-driven behavior costs is Morningstar’s annual Mind the Gap study, which compares fund returns with the dollar-weighted returns investors actually earned. In the 2025 edition, covering the 10 years through December 31, 2024, the average fund returned about 8.2% a year, while the average dollar invested in those funds earned about 7.0%. That 1.2 percentage-point gap came from buying and selling at the wrong times. Morningstar has consistently found that the gap is widest in narrow, exciting sector funds and smallest in boring allocation funds like balanced and target-date funds.
Notice what that means. The investors who did best weren’t the ones who correctly bet against the crowd. They were the ones who held something that made betting unnecessary.
What the Data Supports Instead: Herd on Purpose
The alternative isn’t fighting the herd. It’s choosing the one herd that has a structural edge, then removing yourself from decisions where social proof can reach you.
The index fund is the ultimate “herd” investment, and that’s the point
Buying a total-market index fund means owning every stock in roughly the proportion the entire market owns it. It is, quite literally, holding what everyone else holds. And it has beaten most professional stock-pickers. S&P Dow Jones Indices’ SPIVA U.S. Year-End 2025 Scorecard found that 79% of actively managed large-cap U.S. funds underperformed the S&P 500 in 2025, the fourth-worst year for active large-cap managers in the scorecard’s 25-year history. Over longer periods, the underperformance rate in past SPIVA reports has been even higher.
Investors have noticed. According to Morningstar data reported at the start of 2024, passive U.S. mutual funds and ETFs held about $13.3 trillion at the end of 2023, edging past the just over $13.2 trillion in active funds for the first time. Passive took in roughly $529 billion that year while active funds lost around $450 billion.
There’s an irony worth sitting with here. The most popular investment trend of the last two decades, a genuine stampede into index funds, is also one of the best-supported decisions in finance. Popularity didn’t make it right. The math did: low costs, broad diversification, and no reliance on anyone’s ability to predict what the crowd does next. If you want a concrete starting point, our three-fund portfolio guide for beginners lays out the simplest version of this approach.
Good herding vs. bad herding
The useful distinction isn’t “with the crowd” vs. “against the crowd.” It’s whether the crowd behavior you’re joining depends on timing and attention or on evidence and time in the market.
| Signal | Harmful herding | Helpful herding |
|---|---|---|
| Why you’re buying | It’s up a lot recently and everyone’s talking about it | Decades of evidence on costs and diversification |
| Time horizon | Days to months | Years to decades |
| What you hold | One stock, coin, or narrow sector fund | Broad index or target-date fund |
| Exit plan | “I’ll sell when it feels like the top” | Rebalance on a schedule; sell for goals, not headlines |
| Information source | Social feeds, forums, trending tickers | Written plan, fund prospectus, fee data |
| Typical result | Buying after the run-up, selling after the drop | Closer to the fund’s actual return (smaller Mind the Gap shortfall) |
A Herd-Proof Fix for Herd Mentality Investing You Can Set Up This Weekend
Since willpower is unreliable against social proof, the goal is to make the herd irrelevant to your day-to-day decisions. These steps do that without requiring you to out-guess anyone.
- Automate contributions. A fixed amount into a broad fund every payday means there’s no decision for the crowd to influence. You buy in hype months and panic months alike, which is exactly the behavior Mind the Gap rewards.
- Write a one-paragraph investment policy. Your target allocation, when you rebalance, and the only reasons you’ll sell. When a hot tip arrives, the question becomes “does this fit the paragraph?” rather than “is this going up?”
- Cap your “fun money” bucket. If you want to own a trending stock, give yourself a hard limit, such as a small single-digit percentage of the portfolio. FOMO gets an outlet; the retirement money doesn’t get touched.
- Add a 72-hour rule for any new position. Barber and Odean’s data shows attention-driven buying clusters on the exact days a stock is in the news. A forced delay pushes your decision past the attention spike.
- Stop checking prices daily. Frequent checking amplifies both the fear and the greed that drive herd moves. Quarterly is plenty for a long-term portfolio.
- Audit your inputs. List the accounts and channels you get investing ideas from. If most of them earn money from engagement, that’s a herd generator, whichever direction it points.
A system like this also blunts related biases. Chasing whatever went up last quarter is closely tied to recency bias in investing, and trying to buy the “overdue” beaten-down sector borders on the gambler’s fallacy in investing. A pre-committed plan defuses all three at once.
What could steady, automated contributions grow to if you never chased a single trend?
What I Learned Testing This in My Own Portfolio
Working in software means I’m surrounded by people who get excited about new technology, and a few years back that excitement spilled straight into my investing. Every time a sector got hot, I felt the pull to “do something” with it. I tried the contrarian version too, buying a little of whatever looked hated, mostly out of curiosity about whether the behavioral economics books were right. The honest result: neither the trend bets nor the contrarian bets moved the needle compared with the boring index funds sitting in my tax-advantaged accounts. What actually helped was automation. Once contributions ran on a schedule and I wrote down my allocation, the hype cycles became something I read about instead of something I traded on. As someone who automates everything at work, it’s a little embarrassing it took me that long to automate the one decision most vulnerable to emotion.
When the Standard Contrarian Advice IS Right
None of this means contrarian thinking is useless. It works well in a few specific situations:
- Rebalancing. Rebalancing is disciplined contrarianism. When stocks surge and your allocation drifts, you trim them; when they crash, you buy more. You’re going against the crowd, but on a schedule and by formula, not by gut feel.
- Staying invested during a crash. If the crowd is selling everything during a panic, not joining them is the contrarian move, and it’s one Mind the Gap data strongly supports. You don’t have to buy aggressively; just don’t sell.
- Ignoring product fads. When a new fund type launches with a flood of inflows after a hot run, skepticism is warranted. Morningstar’s research has repeatedly shown the biggest investor return gaps in narrow, trend-driven categories.
- Personal spending decisions. “Everyone has a new car” or “everyone’s buying a bigger house” is herd pressure too. Saying no there is contrarian and almost always financially sound.
The common thread: contrarianism works when it’s rule-based and protects a long-term plan. It fails when it becomes another way to forecast short-term price moves.
Key Takeaways
- Herd mentality investing is real and measurable: individuals pile into stocks on high-attention days, and 50% of Gen Z investors admit to at least one FOMO-driven investment.
- “Be a contrarian” is still a timing strategy, and bad timing is exactly what costs investors, about 1.2 percentage points a year in Morningstar’s latest Mind the Gap study.
- Broad index funds are a crowd worth joining: 79% of active large-cap funds trailed the S&P 500 in 2025.
- Automation, a written plan, a capped “fun money” bucket, and a waiting period beat willpower against social proof.
- Contrarianism works when it’s rule-based, like rebalancing or refusing to panic-sell, not when it’s another short-term bet.
This article is for educational purposes and is not individualized investment advice.
Photo by Sam Carter on
Unsplash
