What if the real American exceptionalism now lies beyond America's biggest stocks?

Key Takeaways

  • Concentration risks: US exceptionalism of the last decade has become dependent on a handful of mega-cap stocks. Just seven companies currently account for more than a quarter of the US S&P 500 Index.

  • Valuation gap: Investors are also paying the highest prices for the most crowded part of the market. That is a dangerous combination. The 10 largest companies in the S&P 500 Index trade at 34x earnings, compared with an average of 22x earnings for the remaining 490 companies.

  • Looking beyond the obvious: We’re finding compelling opportunities within the healthcare sector and founder‑led companies that we believe combine durable economics with long-run AI tailwinds, without paying “headline” AI valuations.

Author: Simon Skinner

Simon Skinner, Master of Arts (Honours) in Law (University of Oxford), Solicitor, Chartered Financial Analyst. Simon joined Orbis in 2008 and is a Director of Orbis Holdings Limited. He leads the London-based Global Investment Team and oversees the specialist teams that support investment research. He previously worked as a derivatives lawyer at Linklaters.

Key Takeaways

  • Concentration risks: US exceptionalism of the last decade has become dependent on a handful of mega-cap stocks. Just seven companies currently account for more than a quarter of the US S&P 500 Index.

  • Valuation gap: Investors are also paying the highest prices for the most crowded part of the market. That is a dangerous combination. The 10 largest companies in the S&P 500 Index trade at 34x earnings, compared with an average of 22x earnings for the remaining 490 companies.

  • Looking beyond the obvious: We’re finding compelling opportunities within the healthcare sector and founder‑led companies that we believe combine durable economics with long-run AI tailwinds, without paying “headline” AI valuations.

When one area of the market delivers so consistently for so long, it’s easy to forget an uncomfortable truth: even the best investments become vulnerable when they get too crowded. Today, the “American exceptionalism” story of the last decade has become a concentrated dependence on a handful of mega-caps. Just seven US stocks—Alphabet, Amazon, Apple, Meta, Microsoft, Nvidia, and Tesla (the so-called Magnificent Seven)—have powered nearly all of the S&P 500’s gains in 2025 and now account for more than a quarter of the US index. The result has been a challenging environment for active managers. Those who have tried to look for bargains among the laggards have been punished severely—if not already fired by their clients! Meanwhile, those who blindly followed the herd have been handsomely rewarded. With so few active investors willing or able to do anything but follow the crowd, we are reminded that, historically, it has been exactly such dynamics that have created the conditions for sharp and extended reversals.

“At a time when macroeconomic and geopolitical risks feel as unpredictable as ever, diversification matters.”

Crowded, fragile and expensive

On top of extreme concentration risk comes valuation risk. The ten largest stocks in the S&P 500 now trade at a lofty 34x earnings. While they may be fantastic businesses, investors are paying the highest prices for the most crowded part of the market. That is a dangerous combination—and leaves little room for error if the fundamentals fail to keep pace with expectations.

High prices are being paid for the largest US stocks​

S&P 500 forward price-to-earnings* ratio for top ten largest stocks vs remaining 490

30 Sep 2025 | Source: LSEG Datastream, LSEG I/B/E/S Estimates, Orbis. Statistics are compiled from an internal research database and are subject to subsequent revision due to changes in methodology or data cleaning. *LSEG I/B/E/S Estimates forecast forward price to earnings for the current fiscal year.

Outside the ten largest names, the remaining 490 trade at a more reasonable 22x earnings on average. But a simple price-to-earnings valuation masks the true extent of the euphoria in the largest US stocks. US profit margins are also near cyclical highs—the stellar returns of the Magnificent Seven have been driven not just by rising valuations but also by huge levels of earnings growth. Stripping out the effect of increased profit margins by looking at valuations on a price-to-revenue basis, we can see the enormity of the valuation gap between the top 10 US stocks and the rest. Currently, the ten largest US companies trade at valuations that are three times higher than the remaining 490 names, at levels that surpass even the height of the 2000s dotcom mania.

On a price-to-sales basis, valuations are higher than during the dotcom bubble ​

S&P 500 trailing price-to-sales ratio for top ten largest stocks vs remaining 490​

30 Sep 2025 | Source: LSEG Datastream, Orbis. Statistics are compiled from an internal research database and are subject to subsequent revision due to changes in methodology or data cleaning.​

Not only is this valuation gap wide, it is also a striking reversal from much of the past 20 years, when the rest of the market regularly traded at a premium to their mega-cap peers.

“Real diversification comes from businesses with durable economics, defensible positions, and leaders who can navigate uncertainty with conviction.”

Overlooked opportunities in the US

Happily, the US is a large place, and when the spotlight shines brightly on the largest names in the index, there is often plenty of value to be found elsewhere. Two areas of neglected opportunity stand out to us—healthcare and entrepreneur-led companies. Healthcare combines resilience with powerful long-term growth drivers. Ageing populations, breakthrough biotech innovations, and the growing need for specialised services are reshaping the sector. Yet despite these structural tailwinds, healthcare stocks—including the very largest names—have lagged the market’s recent rally, leaving select opportunities attractively priced. Our investments span a wide spectrum. Alnylam Pharmaceuticals and Insmed are advancing cutting-edge therapies. UnitedHealth Group and Elevance dominate US managed care, with scale and data advantages that are hard to replicate. Steris leads in sterilisation and infection prevention—an essential, recurring service. Bruker provides precision instruments that underpin both academic and industrial research. We believe these are businesses with defensible niches and steady demand, largely insulated from the market’s obsession with a handful of mega-cap tech stocks.

The 10 largest stocks in the S&P 500 Index trade at an average 34x earnings, compared to 22x for the remaining 490 constituents.

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We also find compelling opportunities in companies where the founder remains deeply involved and heavily invested alongside shareholders. Such leaders tend to think long term, take calculated risks, and build with resilience in mind. Our experience suggests that founder-run companies are more agile, more decisive, and more willing to take appropriate innovation risks—all of which position them ahead of peers as the technology landscape shifts. Interactive Brokers exemplifies this alignment—founder Thomas Peterffy still owns the majority of the company. Others, such as QXO and Corpay, are backed by proven entrepreneurs with a track record of building durable businesses across multiple cycles. While these companies are not immune to volatility, their governance and ownership structures create strong incentives to focus on value creation over the long haul. In many of these cases, we can see long-term opportunities for AI applications to materially improve these businesses—for the time being, these are not contemplated by other investors who are seeking obvious “AI plays”. As patient, long-term investors, we are happy to wait for these impacts to be evidenced in the fundamentals of these businesses. Over decades of implementing the same approach, we know that, sooner or later, fundamental value is reflected in equity prices. At a time when macroeconomic and geopolitical risks feel as unpredictable as ever, diversification matters—but not the cosmetic kind offered by a benchmark dominated by stocks that are all largely reliant on a single technology bet. Real diversification comes from businesses with durable economics, defensible positions, and leaders who can navigate uncertainty with conviction. In this environment, the edge doesn’t come from owning everything—it comes from having the courage to be selective and the discipline to avoid the rest.

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