There is a dangerous illusion developing in today’s markets.

A remarkably small part of the market has generated a disproportionate share of recent returns. Over the past several months, performance has become increasingly concentrated in a handful of AI-related companies, semiconductor stocks, and more recently precious metals such as gold and platinum.

When this happens, something interesting occurs.

The strongest performers begin to dominate headlines, conversations, fund rankings and investor attention. Their success creates compelling narratives explaining why they deserve to continue outperforming. Every gain appears to validate the story. Every new high reinforces the belief.

It begins to feel obvious. But investing has a habit of making the obvious expensive.

The Performance Distortion

Periods of narrow market leadership create an optical illusion.

High-quality businesses outside the fashionable sectors can appear disappointing simply because they are not participating in the frenzy. Value-oriented companies begin to look “broken.” Diversified portfolios suddenly seem dull and uninspiring.

Nothing may have fundamentally changed about these businesses. Only the comparison has changed. When a small group of companies compounds at extraordinary rates, almost everything else looks mediocre by comparison.

This is one of the greatest behavioural challenges investors face.

The Seduction of Recent Performance

Our brains are wired to extrapolate.

When we observe exceptional recent performance, we naturally assume it will continue. We seek evidence that confirms our belief and become increasingly confident in stories explaining why “this time is different.” The narrative becomes stronger precisely because prices have already risen.

Ironically, this is often when risk is quietly increasing. Not because the companies are necessarily poor businesses, but because expectations have become extraordinarily high.

Concentration Changes More Than Returns

Most investors think concentration simply changes expected returns. It does far more than that.

Concentration changes the range of possible outcomes. The more concentrated a portfolio becomes, the more dependent it is on a very small number of future events unfolding exactly as hoped.

Success becomes spectacular. Failure becomes painful. The outcome depends heavily on when you invested and whether the narrative continues long enough to justify today’s prices.

This is an important but often overlooked reality. As concentration increases, luck begins to play a larger role.

The Impossible Question

Every generation asks the same question: “Which companies will dominate the next decade?”

Unfortunately, the question cannot be answered with certainty. History repeatedly shows that wealth creation is concentrated in a surprisingly small number of companies. Yet history also shows that identifying those winners in advance is extraordinarily difficult.

Today’s winners are visible only because we are looking backwards. Tomorrow’s winners remain hidden. This is why concentration is such a difficult decision. The “right” amount of concentration is unknowable beforehand. You only discover whether you were right after the fact.

Why Diversification Still Matters

Diversification is often criticised during periods of concentrated markets because it inevitably owns businesses that are not leading performance. That is precisely its purpose.

Diversification accepts that we cannot reliably predict where future returns will come from. It recognises that leadership changes, narratives evolve and yesterday’s certainty can become tomorrow’s disappointment.

Rather than attempting to identify the next dominant theme with perfect accuracy, diversification spreads uncertainty across many possible futures. It is an admission of humility, not ignorance.

The Real Choice

Investors are often told that concentration demonstrates conviction. Sometimes it does. But concentration also represents confidence that you know something about the future that the market does not.

Diversification makes a different statement. It acknowledges that the future is uncertain and refuses to bet everything on a single narrative.

There will always be periods when concentrated portfolios outperform spectacularly. There will also be periods when they disappoint just as spectacularly. The challenge is that no one knows in advance which period lies ahead.

That is the concentration conundrum.

The goal of investing is not to own whatever has performed best recently. It is to build a portfolio capable of surviving futures that no one can predict.

Concentration is a choice about how much certainty we believe we possess. The future has a way of humbling certainty.

A diversified investor simply chooses to be humble before the market does it for them.

 

Written by Marius Kilian