The third quarter’s strongest signal was the gap between how resilient the major indexes looked and how many individual stocks had already fallen well below their highs. At the same time, strong demand for artificial intelligence is arriving alongside a costly infrastructure buildout, while Middle East supply disruptions are lifting fuel-price risk. The central question is whether earnings and economic growth can keep absorbing those
pressures.

We entered Q3 watching whether growth and earnings could support market expectations, with Middle East risk important chiefly through its economic effects. During the quarter, oil disruptions pushed fuel prices higher, while the S&P 500’s near-high finish masked less broadly shared gains.

Key Takeaways

·   Market strength remained concentrated, with broad weakness beneath the S&P 500’s near-high close. ¹

·   AI demand is strong, but investors still need to see how large investments translate into durable cash returns. ²

·   The latest available GDP report showed growth in Q2; September inflation and labor data arrived after the quarter ended. ³,⁶,⁷

·   Middle East supply disruptions created a real risk to fuel prices and the inflation outlook. ⁵,⁷

A strong index can hide a weaker market

At first glance, the quarter looked resilient. The S&P 500 ended September about 2% below its highest daily close over the prior 12 months. Beneath that headline, 401 of 502 S&P 500 constituents with usable data, about 80%, were more than 10% below their own 12-month closing highs. 197 stocks, about 39%, were more than 20% below. The more-than-20% group is included in the more-than-10% group. This gap shows how an index near its high can coexist with weakness across many of its constituents.¹

AI demand is real; the return still has to be earned

That narrow leadership keeps attention on the companies carrying the market. The AI
questions investors are asking are practical: Is demand turning into recurring
revenue? Will the spending earn an attractive return? How much will
infrastructure costs weigh on margins and cash flow while companies build
capacity?

Alphabet’s second-quarter results show both sides of the story. Google Cloud revenue grew 82%, while capital spending reached $44.9 billion and free cash flow was negative $5.9 billion for the quarter. The company said most capital spending supported AI infrastructure and raised its full-year capital-spending outlook. Strong demand is visible; the return on that investment will take time to assess. ²

Growth continues, but inflation still matters

The latest GDP reading available at quarter-end was for Q2: the economy grew at a 2.2% annual rate. That describes the previous quarter, not Q3. In September, the Federal Reserve raised its target range by a quarter point to 3.75%–4.00%. The combination of continued growth and a rate increase illustrates the challenge of balancing economic momentum with inflation that remains a concern. ³,⁴

Middle East risk reaches the fuel bill

The conflict in the Middle East became a more direct economic risk as oil flows were disrupted and fuel prices rose. The U.S. Energy Information Administration reported that Brent crude averaged $114 per barrel in September, up $23 from August, following attacks on oil infrastructure and tankers in the region. EIA forecast an average of $105 per barrel for Q4 and warned that constrained flows could keep prices volatile. That forecast depends on assumptions about supply routes and production, so it should be read as a
scenario, not a certainty. ⁵

If higher fuel costs persist, they can squeeze household budgets and raise business costs. That would add to inflation pressure and could complicate the Federal Reserve’s decisions. How much it matters will depend on how long supply routes remain constrained and how quickly production and exports recover. ⁴,⁵,⁷

What we learned after quarter-end

Data published in October added a mixed signal. September payrolls increased by 29,000, and unemployment was 4.2%. Consumer prices rose 0.6% in September; gasoline rose 9.1% and accounted for more than half of the monthly all-items increase. Core prices, excluding food and energy, rose 0.3% for the month and 2.6% over the year. These figures describe September, but they were released after Q3 ended. ⁶,⁷

Figure 2. Monthly CPI changes in September 2026, seasonally adjusted. Source: U.S. Bureau of Labor Statistics; see endnote 7.

As of October 20, the advance estimate of Q3 GDP had not been released; BEA scheduled it for October 29. ⁸

What We’re Watching

·   Market breadth: Can more companies participate in gains, or will leadership remain
concentrated?

·   AI returns: Do revenue, margins, and cash flow begin to justify the scale of
infrastructure spending?

·   Fuel and inflation: Do supply disruptions ease, or do energy costs keep pressure on
households, businesses, and inflation?

·   Growth and policy: Does incoming data support continued expansion without
reigniting inflation?

The quarter ended with indexes that looked stronger than the typical stock, an AI investment cycle with visible demand and rising costs, and a new source of inflation risk in energy markets. The next test is whether earnings broaden, AI spending produces lasting returns, and fuel prices stabilize enough to keep inflation from becoming a
larger obstacle. ¹,²,⁵,⁷