What Q2 earnings reveal about whether the AI rally is overvalued, and what it means for S&P 500 concentration risk.
KEY TAKEAWAYS
- Roughly 86% of S&P 500 companies beat earnings estimates this quarter, above both the five and ten-year averages, and the growth behind those beats has been real rather than a product of easy comparisons.
- Much of that growth remains concentrated in a small group of AI infrastructure companies, keeping the index’s top 10 holdings at nearly 40% of total weight, per Pensions & Investments.
- Capital spending on AI infrastructure is now outpacing free cash flow at several mega-caps, a shift from the capital-light profile that helped justify their premium valuations.
- Despite that earnings strength, the Magnificent Seven returned negative 1.7% on an equal-weighted basis through the first half of 2026, trailing U.S. mid-caps, small-caps, and international equities, which each posted gains of 14% to 22% over the same period.
- AI spending is producing real growth. The open question is whether that growth is broad enough to offset the concentration and price risk built into a passive S&P 500 allocation.
ARE MEGA-CAP TECH EARNINGS JUSTIFYING CURRENT VALUATIONS?
Partly. Real revenue and profit growth from cloud and AI-linked businesses gives this rally a genuine fundamental backbone, though that backbone sits under a small number of companies.
This has been one of the stronger earnings seasons in recent years. Through late July, roughly 86% of S&P 500 companies had beaten earnings-per-share estimates, above both the five-year average of 78% and the ten-year average of 76%, according to FactSet. Analysts had raised estimates heading into the season, the opposite of the usual pattern.
Amazon’s second-quarter results show why. AWS revenue reached $42.2 billion, up 37% year over year, its fastest growth in eighteen quarters and ahead of the 31% analysts expected. Total revenue crossed $200 billion for the first time, up 20% year over year, with operating income up 43% to $27.5 billion. Given results like these, it is not surprising that many analysts have taken a bullish view on the stock.
Aggregate figures can still overstate the picture. Alphabet posted an unusually large earnings surprise this quarter, driven by a gain on its SpaceX investment rather than core operating performance, and that gain is doing a lot of the lifting behind the index’s blended growth rate. A similar boost may not repeat next quarter. Strip Alphabet’s contribution out and blended growth still shows real strength, just less dramatic. A strong index-level number can still rest on a handful of names.
IS THE AI RALLY OVERVALUED?
Not across the board, but the market is paying a premium for a narrow group of winners, and that premium becomes harder to defend if AI spending slows or monetization lags expectations.
The clearest evidence is capital intensity. Amazon raised its 2026 capex guidance to roughly $220 billion, up from $200 billion, for AI and cloud infrastructure. Trailing twelve-month free cash flow swung to a $7.6 billion outflow from an $18.2 billion inflow a year earlier. The pattern is not limited to Amazon: capital expenditures at several large cloud and AI infrastructure providers are now growing faster than operating cash flow.
It is the same shift Austin Graff and Manav Shah flagged earlier this year in Wealth Management’s 2026 Market Outlook: hyperscalers once prized for capital-light, high-margin models are now directing more of their operating cash flow into AI infrastructure with uncertain near-term returns. That does not make the spending irrational. Demand signals, backlog growth, and management commentary this earnings season point to real capacity constraints, not speculative build-out. It does mean the market is pricing a small group of companies on future monetization rather than current free cash flow.
That premium has not held up well in 2026, at least by one measure. On an equal-weighted basis, the Magnificent Seven, Apple, Microsoft, Amazon, Alphabet, Meta, Nvidia, and Tesla, returned negative 1.7% through the first half of 2026, while U.S. mid-caps, small-caps, and international equities all posted gains of 14% to 22% over the same period.
“Investors have grown more focused on underlying profitability and free cash flow growth, especially given the large capex commitments announced in 2025 and continuing through 2026,” says Manav Shah, Portfolio Manager at Opal Capital. “This has sharpened the distinction between capital-light and capital-intensive business models, and capital flows have increasingly tilted toward cash-generative companies rather than the Magnificent Seven, where valuations remain relatively elevated even as forward profitability and cash flow growth show signs of deterioration.”
IS S&P 500 CONCENTRATION GETTING WORSE?
Yes. The index remains historically top-heavy, and this earnings season reinforced that rather than easing it.
This is where earnings strength and the concentration risk we flagged in our July piece on S&P 500 concentration meet. The top 10 holdings currently represent nearly 40% of the index’s total weight, according to Pensions & Investments, near the highest level on record. Those same 10 companies generate closer to 34% of the index’s aggregate profits.
That gap matters. Weight has run ahead of earnings share, meaning investors are paying for expected future growth, not just today’s profits. That is not unreasonable given the growth rates involved, but it means the risk in a passive S&P 500 allocation is increasingly tied to whether that growth shows up. We saw a version of this internationally in our Diversification Illusion piece, where the MSCI Emerging Markets Index has quietly become a concentrated bet on East Asian semiconductor manufacturing. Concentration is not just a U.S. large-cap story this year, and it is showing up across benchmarks investors have long treated as diversified.
WHAT THIS MEANS FOR PORTFOLIO CONSTRUCTION
For advisors, the practical takeaway is less about timing the AI trade and more about understanding what is driving client portfolios. A passive S&P 500 allocation still captures the upside from AI-linked earnings growth, but it also means carrying the concentration risk that comes with it, whether that exposure was intended or not.
The right response is not to abandon AI-driven growth, but to make sure exposure to it is a deliberate decision rather than one inherited by default. That starts with reviewing how much of a portfolio’s expected return depends on a small number of mega-cap names, then deciding whether that concentration fits the plan. Discipline here matters more than prediction.
FREQUENTLY ASKED QUESTIONS
What is S&P 500 concentration risk?
Concentration risk refers to how much of an index’s performance depends on a small number of holdings. In the S&P 500, the top 10 companies currently account for nearly 40% of the index’s total weight, according to Pensions & Investments, meaning their performance disproportionately drives the returns of investors who hold the broader index.
Did Q2 2026 earnings support current AI stock valuations?
Partly. Companies most exposed to cloud and AI infrastructure demand, including Amazon’s AWS segment, reported revenue and profit growth well ahead of analyst estimates. That growth supports valuations for the leaders driving it, but it is concentrated in a relatively small group of companies rather than broad-based across the index.
Is AI capital spending affecting free cash flow at large tech companies?
Yes. Several large cloud and AI infrastructure providers have seen capital expenditures grow faster than operating cash flow this year, pressuring free cash flow even as revenue and operating income continue to grow. Amazon, for example, raised its 2026 capital spending guidance to roughly $220 billion while its trailing twelve-month free cash flow moved negative.
How can investors manage S&P 500 concentration risk?
Approaches vary, but common options include pairing a core index allocation with actively managed strategies designed to reduce overlap with the largest holdings, and maintaining international or asset-class diversification alongside U.S. large-cap exposure. Each approach carries its own tradeoffs and can underperform a concentrated, mega-cap-led rally over shorter periods.
Sources & Notes
1. FactSet Earnings Insight, S&P 500 Earnings Season Update, week of July 24, 2026. https://insight.factset.com/sp-500-earnings-season-update-july-24-2026
2. Amazon.com, Inc., Second Quarter 2026 Earnings Release, July 30, 2026. https://www.aboutamazon.com/news/company-news/amazon-earnings-q2-2026-report
3. Microsoft Corporation, Fiscal Year 2026 Second Quarter Earnings Call transcript, January 2026. https://www.microsoft.com/en-us/investor/events/fy-2026/earnings-fy-2026-q2
4. S&P 500 top-10 index weight (nearly 40%): Pensions & Investments, “Top 10 stocks account for nearly 40% of the S&P 500,” January 2026. https://www.pionline.com/data-rankings/chart-of-the-day/pi-sp500-index-concentration/
5. Top-10 index profit share (~34%): Apollo Global Management, “Top 10 Companies Account for 34% of Profits in the S&P 500,” May 2026. https://www.apollo.com/wealth/the-daily-spark/top-10-companies-account-for-34-of-profits-in-the-sp-500
6. Top-10 index profit share, as cited in Yahoo Finance, “The S&P 500 Is On Track to Post Record Q2 Profits, But There’s a Catch,” July 2026. https://finance.yahoo.com/markets/stocks/articles/p-500-track-post-record-133352402.html
7. Magnificent Seven equal-weighted return and comparative index returns (S&P 400, Russell 2000, MSCI ACWI ex-U.S.)