arvy Notes · Market Analysis

When 60% of the S&P 500 Is AI — Quality Becomes the Allocation Question

Diversification has quietly left the broadest US benchmark. Quality stocks simultaneously trade at their lowest relative level since 1999. A portfolio allocation analysis for 2026.

Written by Thierry Borgeat, Co-Founder of arvy · Reviewed by Patrick Rissi, CFA and Florian Jauch, CFA · 15 May 2026 · 5 minute read

Two market observations, one central thesis on portfolio allocation in 2026. The concentration of the S&P 500 has reached a level where a passive index product is economically barely distinguishable from a thematic AI bet. Quality stocks — as an asset class with low exposure to the dominant market narrative — simultaneously trade at a historically attractive relative valuation. For institutional and private Swiss investors, this is less a market-timing question than a strategic allocation question.

1. Diversification Has Quietly Left the S&P 500

Gewicht von Halbleitern (Semis, wie Nvidia, Micron Technology, Broadcom und Co, im S&P 500

The S&P 500 today is no longer a broadly diversified equity benchmark. Its ten largest constituents — NVIDIA, Apple, Microsoft, Alphabet, Amazon, Meta, Broadcom, Tesla, Berkshire Hathaway, JPMorgan — represent roughly 35–38% of the total index. NVIDIA alone, at around 7%, accounts for more than the bottom 100 names of the index combined.

Looking beneath the surface, the picture sharpens further. By our sector classification, around one-fifth of the S&P 500 sits directly in semiconductor names (NVIDIA, Broadcom, AMD, Texas Instruments, Qualcomm, Applied Materials, Lam Research, Analog Devices, Micron, and others). Extending the definition to companies whose valuation multiples are primarily driven by the AI narrative — hyperscaler cloud providers, AI-software platforms, AI-infrastructure hardware, AI-adjacent consumer names — we estimate around 60% of the S&P 500 is AI-narrative-exposed.

For a Swiss investor invested "globally diversified" through an MSCI World or S&P 500 ETF, something quiet but fundamental has changed. What was a broadly diversified US equity portfolio ten years ago is today predominantly a thematic bet on the success of a single technology trend. That bet may pay off — or it may not. Either way, it is no longer diversification.

The resulting question is not whether AI is a transformative technology (it is), but whether a single theme should constitute 60 percent of an investment portfolio. From a risk-management perspective, the answer is unambiguous: no.

2. Quality at 1999 Levels — and Momentum 5 Sigma Above Trend

Left — Refinitiv, Jeff Weniger, as of 10 November 2025: 6-month relative return of the S&P 500 Quality Index versus the S&P 500. Right — Bloomberg Opinion, Bloomberg Factors To Watch: long-short total return of the FTW US All-Cap Momentum factor versus Quality since 2 April 2025 ("Liberation Day").

While concentration in the index has intensified, Quality as a factor has systematically lagged. The left half of the chart above documents this clearly: the 6-month relative return of the S&P 500 Quality Index against the broad S&P 500 currently stands at -11.5%. That is exactly the level of April 1999 — the last time Quality investors lagged as severely as today. The only other data point of the past 30 years that comes close is October 2025 (-8.8%).

The right half shows how this manifests today: since 2 April 2025 — labelled "Liberation Day" by the market — the FTW US All-Cap Momentum factor has gained around 7%. The corresponding Quality factor (strong balance sheets, low debt, consistent cash flows, high returns on equity) has lost around 22% over the same period. A spread of roughly 30 percentage points between the two factors in twelve months is historically unusual.

Source: MSCI, Alpine Macro 2026. Ratio of US Momentum stocks to US Minimum Volatility stocks, based on large- and mid-cap indices.

The quantitatively even clearer observation comes from Alpine Macro: the price ratio of US Momentum stocks to US Minimum Volatility stocks today stands five standard deviations above its long-term trend — higher than in the three comparable episodes of March 2000, June 2008, and February 2021. We do not claim that a direct market-timing signal can be derived from this indicator alone. But it makes one thing very clear: the relative valuation of Quality stocks versus the market has not been more attractive in 25 years.

Three times in 25 years, this setup has initiated multi-year Quality outperformance. But our argument today is not primarily historical — it is structural: Quality delivers the real diversification the broad index can no longer offer.

Implications for Investors — arvy's Allocation View

We are not writing this note to forecast a rotation over the next weeks or months. Market regimes cannot be timed with precision — not even by CFA Charterholders with a robust understanding of factor cycles. It is plausible that the current constellation persists for another twelve months. It is equally plausible that it resolves faster than it feels in the middle of it.

What the data does establish clearly is this: when a single thematic narrative drives 60 percent of a global standard benchmark, and the asset class with the lowest exposure to that narrative simultaneously trades at the most attractive relative valuation in history, the allocation question is structurally settled. Quality belongs in every diversified portfolio — not as a speculative contrarian bet, but as a legitimate pillar of construction.

At arvy, we are positioned in our Quality equity fund in around 30 global companies that meet our Quality criteria: consistent and growing free cash flows, low net debt, high and stable returns on equity, attractive valuation in historical context. These companies deliver what the index heavyweights can structurally no longer provide to the same extent: genuine diversification against the dominant market narrative.

We are a Swiss asset manager, FINMA-regulated under CISA Art. 24, with our own capital invested in the same fund as our clients. We understand that Quality investing has been uncomfortable in this phase — the past twelve months made that clear. But the allocation logic does not weaken over time, it strengthens.

Vanguard Advisor Alpha estimates the behaviour-gap cost of the average investor at 1.5% per year. Most of that cost is incurred in phases like this one — when a single narrative dominates the market and discipline is most uncomfortable. Quality allocation is the structural answer to precisely that temptation.