The third quarter of 2026 delivered a market environment that demanded clarity from investors: rising yields, a Fed resuming its tightening campaign, energy prices surging back into the conversation, and an equity rally that narrowed even as it continued. In its October 1 market commentary1, Astoria Investment Management lays out the connective tissue between these forces and, critically, where the stress points lie heading into the fourth quarter.
A Rally That Narrowed as It Climbed
The S&P 500 posted a 2.3% gain in Q3, but the distribution of returns told a more cautious story. US growth stocks led with a 3.6% quarterly gain, followed by US large-caps at 2.4% and US value at 1.0%. The divergence at the other end was sharp: US small-caps fell 8.0% and US mid-caps dropped 6.4%. Bonds, meanwhile, offered little shelter. Municipal bonds fell 5.3%, 7-10 year US Treasuries declined 4.6%, and investment-grade corporates shed 4.1%. The one unambiguous bright spot was commodities, with crude oil surging 36.8%, broad-based commodities gaining 15.8%, and gold adding 3.4%.
The Fed Steps Back In
The Federal Reserve's September FOMC decision was the quarter's most consequential event. Astoria notes that the Fed raised the federal funds rate by 25 basis points, lifting the target range to 3.75 to 4.00% in a unanimous 12 to 0 vote. Chair Kevin Warsh framed the move as removing "a dose of accommodation," declining to offer forward guidance and instead explaining why the Fed acted now after pausing in July. The motivation was direct: Warsh stated that "the plain fact is that inflation is too high and has been for too long." The data supported the call. August Nonfarm Payrolls rose 162,000 against expectations of roughly 60,000, while headline CPI held at 3.4% year-over-year, and core PCE was running at 3.3% as of July. The updated Summary of Economic Projections penciled in one more hike this year, lifting the median year-end funds rate to 4.1% from 3.8% in June.
Two Inflation Stories Running Simultaneously
Astoria draws a careful distinction between the surface-level inflation data and what is happening beneath it. On the headline side, WTI crude climbed back above $90 a barrel and the national average price of diesel reached a record nominal high of over $6.50 per gallon in late September. Beneath the surface, though, Astoria observes that the Cleveland Fed's trimmed-mean and median CPI both slowed, as did the Atlanta Fed's sticky-price CPI, which tracks items whose prices change infrequently and tend to reflect longer-term expectations. The August PCE report released at the end of September brought some additional relief, with core PCE easing to 3.0% and headline PCE slowing to 3.4% from 3.7%, though both remain above goal.
Yields and Valuations: The Math Still Works, for Now
Treasury yields rose across the curve in September, with the 10-year reaching its highest level since 2002 and the 30-year topping 5.4%. Astoria's analysis attributes the move primarily to oil and stronger nominal growth rather than fiscal concern, noting the term premium has stayed contained. Nominal GDP is running close to 7% on a five-year trailing average, and as Astoria points out, even at a 19-year high, the 10-year yield remains below that pace of GDP growth. That context matters for equity valuations. Forward earnings estimates have climbed on roughly 29.1% expected third-quarter growth, pulling the S&P 500's forward P/E to approximately 19.2x, implying an earnings yield of about 5.1%, in line with the current 10-year yield. Astoria's framework suggests that even if the 10-year reached 5.2%, the resulting 13% valuation haircut would likely be more than offset by continued earnings growth, limiting the risk of a 2022-style drawdown.
The AI Assumption Carrying the Growth Story
The final and perhaps most structurally important section concerns AI investment. Excluding equipment and intellectual property, the components most tied to AI, real GDP grew at just a 0.3% annualized rate in the first quarter and was flat in the second. Capex for the major hyperscalers is now consensus-expected to exceed operating cash flow in both 2026 and 2027, leaving aggregate free cash flow negative. Astoria states plainly that the AI story rests on the single assumption that operating cash flow roughly triples from about $600 billion in 2025 to $2 trillion by 2030. If that assumption does not materialize, credit spreads could widen and capex plans could be scaled back, with potential spillover to broader US growth. That is not a bearish call. It is a risk calibration.
Five Key Takeaways for Advisors and Investors
- Market breadth is narrowing even as headline indices hold. Exposure concentrated in large-cap US growth may be masking vulnerability in mid- and small-cap allocations that advisors should revisit.
- The Fed's return to hiking was data-driven and decisive. With the median year-end funds rate now projected at 4.1%, portfolios with long-duration fixed income exposure face continued headwinds.
- Energy is the wild card. With oil above $90 and diesel at record nominal highs, the lag effect on services inflation remains an active risk that could justify further Fed action beyond what markets currently price.
- Beneath the headline CPI numbers, core disinflation is progressing. Advisors should not conflate the energy-driven headline with the broader disinflationary trend still underway in goods and underlying services.
- The AI investment thesis carries a single, load-bearing assumption: hyperscaler cash flow tripling by 2030. Advisors with significant tech sector exposure should understand that the valuation support rests on that projection materializing as consensus expects.
Footnote:
1 Astoria Investment Management. "Rates Hit Multi-Decade Highs. Will Growth and Earnings Keep the Rally Going?" Astoria Investment Management, 1 Oct. 2026, https://www.astoriaim.com/single-post/rates-hit-multi-decade-highs-will-growth-and-earnings-keep-the-rally-going.
