How to avoid the Dunning-Kruger effect in investing

Imagine this: you open your first brokerage account, make a few trades based on trending stocks on the home page, and within weeks, you’re up 20%. You start thinking, “This investing thing is easy. I have just discovered my hidden talent. Am I the next Warren Buffett?”

Fast forward six months and half your gains have evaporated. You’ve just experienced the Dunning-Kruger effect, which is a cognitive bias where those with the least knowledge tend to be the most confident. In investing, this phenomenon doesn’t just bruise egos; it destroys portfolios. Hence, in this article, we will understand what the effect is about and how to counter it to become a better investor.

What is the Dunning-Kruger effect?

The Dunning-Kruger effect, named after psychologists David Dunning and Justin Kruger, describes a phenomenon where people with limited knowledge in a domain dramatically overestimate their competence.

The journey of learning follows a predictable curve:

1. Newcomers quickly climb the “Peak of Mount Stupid” when starting to learn something, believing they’ve mastered the subject after minimal exposure.
2. Reality then pushes them into the “Valley of Despair” as they begin to learn and discover more, realising there are many things they actually don’t know.
3. With more knowledge equipped, they ascend the “Slope of Enlightenment” toward genuine competence. Paradoxically, true experts often underestimate their abilities because they’re acutely aware of how much they don’t know. The true risk lies in not knowing what you don’t know, and you’re still blindly confident about it, and it sounds pretty scary to me.

Why it happens in investing

The Dunning-Kruger effect applies to any field that involves skills and knowledge, but investing is uniquely susceptible to this effect for several reasons. First, markets appear deceptively simple on the surface, just buy low, sell high. But if you drill down, they contain layers of complexity involving psychology, economics, accounting and probability theory.

Second, beginner’s luck is a common phenomenon. Bull markets lift most boats, and early wins often feel like a validation of a not-yet-developed skill rather than fortunate timing. And more often, the rally of a stock might be because of a different story than what we initially believed and might never have thought of.

Third, the access to information that we have now also creates an illusion of expertise. Reading financial news, analyst reports, and watching market commentary, or even following some YouTuber, can make us feel knowledgeable, even when we still lack the framework to interpret it properly. Confirmation bias amplifies the problem further. With millions of opinions floating around online, it’s never been easier to find support for any investment thesis, no matter how flawed.

Finally, investing also lacks immediate, clear feedback loops. A bad decision may not reveal itself for months or years, and market noise can make it difficult to distinguish between poor judgment and temporary setbacks. Unlike learning things like coding, where errors immediately flag problems and force you to learn and correct them, investing offers no such privileges of instant feedback. This absence of rapid correction allows flawed thinking to persist unchecked.

How to spot the effect

Self-awareness is always your first defence. Watch for these warning signs:

• Overconfidence after early wins: A few successful trades in a bull market convince you that you’ve mastered investing
• Attempting to time the market: Believing you can consistently buy low and sell high, despite evidence that even professionals rarely succeed
• Ignoring diversification: Concentrating heavily in a few stocks because you’re very certain your picks will outperform
• Dismissing expert advice: Rejecting input from experienced investors or financial advisors due to misplaced confidence in your own knowledge.
• Asymmetric outcome attribution: Crediting wins to your skill while blaming losses on bad luck, market manipulation, or external factors
• Failing to track decisions: Not maintaining records of your investment reasoning, making it impossible to learn from mistakes

How to counter the effect

Fortunately, we can develop practices that counteract the Dunning-Kruger effect:

• Keep a decision journal: Before making any investment, document your thesis, expected outcomes, risks, and supporting evidence. This creates accountability and reveals flawed reasoning over time.
• Conduct portfolio post-mortems: With the journal, regularly review (but not too often, as it will create anxiety) both successful and failed investments to understand what you got right and wrong.
• Seek evidence that says otherwise: For every investment idea, spend half or equal time looking for reasons why it could also fail. This forces you to engage with uncomfortable information rather than just collecting supporting data.
• Embrace index funds: Consider using index funds for the majority of your portfolio if you’re starting. This acknowledges the difficultyof consistently beating market returns and protects you from costly mistakes during the learning phase.
• Commit to continuous education: Stay informed of market trends, continuously study behavioural finance, accounting, and market history. The more you learn, the more you’ll appreciate how much you don’t know. With Gen AI, the process is now easier and faster.

The fifth perspective

Here’s the thing: just like any bias, knowing about the Duning-Kruger effect doesn’t make you immune to it. I think that overcoming this bias is a lifelong journey that requires constant vigilance, humility, and occasional reminders. I also believe that successful investors all share a common trait: they’re intimately aware of what they don’t know, willing to admit when they are wrong, and structure their approach accordingly. The main question isn’t whether you’ll experience overconfidence, but whether you’ll recognise it and course correct.