All Your Eggs in One Basket: The Case for Concentration Risk

There is a piece of conventional wisdom in the investing world that sounds so reasonable it rarely gets challenged: diversify. Spread your risk. Don't put all your eggs in one basket.

It's not wrong. But it's incomplete. And for investors whose goal is to outperform the market, it may be the single most reliable path to mediocrity.

First, let's be clear about index investing: If your goal is to capture market returns - to grow your wealth at roughly the pace of the broader economy over time - index investing is a rational, disciplined, and entirely defensible strategy and for many investors, low cost, broad exposure index funds are the right way to go. That is why many clients prefer a core-satellite approach, using passive indexing as a stable core to maintain market parity, while carving out a high-conviction “satellite sleeve”. It is within this satellite portion where true investment savvy lives, and where investors can move beyond mere participation in the market and pursue the kind of returns that indexes, by definition, cannot deliver.

This post is not an argument against index investing, but rather it is an argument against the assumption that more diversification is always better, and that concentration risk is something to be feared rather than understood and embraced.

What the best investors actually do: Warren Buffett put it plainly: "Diversification is protection against ignorance. It makes little sense if you know what you're doing."

Charlie Munger was characteristically blunter: "The idea of excessive diversification is madness."

Stanley Druckenmiller, who managed George Soros's Quantum Fund and produced one of the greatest long-term track records in investment history, has said he prefers to put all his eggs in one basket and watch that basket very carefully. Druckenmiller's view is that the way to build real wealth is through high-conviction bets, sized appropriately, held with patience.

These are not reckless speculators. They are among the most disciplined, analytical investors who have ever lived. And none of them built their records by owning a little bit of everything.

Know what you own, and why: There is an important distinction between concentration that comes from laziness or overconfidence, and concentration that comes from research and judgment. The former is dangerous. The latter is how outperformance is actually generated.

A portfolio of 10 to 15 well-understood positions, each selected for a specific reason, monitored carefully, and sized based on the investor's level of conviction, is not a reckless portfolio. It is a portfolio built on the assumption that the manager actually knows something — and is willing to act on it. Peter Lynch put it best when he said “know what you own, and know why you own it.”

A portfolio of 75 positions or grab bag of different index funds assembled in the name of safety, is often neither safe nor purposeful. A portfolio constructed that way seems to be designed to ensure that no single mistake matters much — but also that no single insight matters much either. Modern portfolio theory tells us that diversification eliminates unsystematic risk, which is the risk specific to an individual company or sector. But when “main street” investors think about stock market risk, their primary concern usually comes from systematic risk - that is, a decline in the entire market due to macroeconomic factors - think the dot com bubble or the global financial crisis of 2008, or more recently the covid pandemic, Diversification doesn’t mitigate systematic risk because it is a whole market risk.

Interestingly in today’s market (spring of 2026) buying an index such as the market-cap weighted S&P 500 means buying into a somewhat surprising risk profile. As of this writing the top ten companies in the S&P500 constitute roughly 40% of the entire index, and eight of them are tech companies. In other words, $40 of every $100 invested into the S&P 500 goes into 10 companies. Buying the S&P500 today is less an act of diversification than a concentrated bet on a handful of large-cap tech companies, with 490 other companies along for the ride.

Be clear about your goals: If the goal is market returns with minimal cost and effort, index funds are excellent tools, but choose wisely. If the goal is to outperform and to build wealth at a rate that exceeds what the market would otherwise deliver, then the path forward requires differentiated thinking, research-backed conviction, and the willingness to hold concentrated positions when the analysis supports it.

You can’t beat the market by owning the market.

The views expressed here reflect my investment philosophy and are intended for educational purposes only. Nothing in this post constitutes investment advice, legal advice, or a recommendation for any specific security or strategy. Every investor's situation is different. If you'd like to discuss how these ideas might apply to your own situation, I'm always happy to talk.