Spiking Bond Yields, Midterms and Earnings to Test US Stocks’ Typical Fourth-Quarter Strength
The fourth quarter is historically one of the strongest periods for U.S. stocks. But as 2026 enters its final three months, investors are facing an unusual combination of rising Treasury yields, political uncertainty, demanding earnings expectations and heavy dependence on artificial-intelligence spending.
The S&P 500 entered October after gaining nearly 13% for the year and sitting roughly 1% below its mid-August record high. The Nasdaq Composite was up more than 15%. That leaves less room for disappointment if earnings, interest rates or corporate spending fail to meet investors' expectations. (Reuters)
The key question for the fourth quarter is therefore not simply whether U.S. stocks can maintain their historical seasonal strength. It is whether strong corporate earnings and the prospect of reduced election uncertainty can offset the pressure coming from a much more expensive bond market.
Why the Fourth Quarter Is Usually Strong for US Stocks
History gives investors a favorable starting point.
Since 1945, the S&P 500 has averaged a 4.2% gain during the fourth quarter, with the index rising in about 85% of those periods, according to CFRA data cited by Reuters. The average fourth-quarter gain has been more than twice the average increase in the other three quarters. (Reuters)
The pattern has been even stronger during U.S. midterm-election years. The S&P 500 has historically averaged a 6.4% fourth-quarter gain in those years, as investors often get greater clarity once the November election is over. (Reuters)
That historical pattern is encouraging, but it is not a forecast.
Markets can still fall during historically strong periods if earnings weaken, inflation rises or financial conditions tighten. In 2026, the bond market is providing exactly that kind of challenge.
Rising Treasury Yields Are the Biggest Immediate Risk
The most visible pressure point is the U.S. Treasury market.
The benchmark 10-year Treasury yield reached 5.34% on October 1, its highest level in 24 years. Yields have risen as investors have dealt with stronger growth expectations, higher energy costs and increased competition for capital as companies borrow to fund large AI infrastructure projects. (Reuters)
For equity investors, higher bond yields matter for several reasons.
First, government bonds become more competitive with stocks when their yields rise. An investor may demand a higher expected return from equities before accepting their additional risk.
Second, higher yields increase borrowing costs for companies and consumers. That can eventually affect investment, housing, business expansion and consumer spending.
Third, higher interest rates can put pressure on stock valuations. This is particularly relevant for growth companies whose valuations depend heavily on profits expected many years in the future.
That does not mean a 5%-plus 10-year yield automatically triggers a stock-market crash. But it can make another major equity rally harder to sustain.
The Federal Reserve Is Back at the Center of the Market
The bond selloff has also put renewed attention on the Federal Reserve.
The Fed raised interest rates in September for the first time in three years as policymakers attempted to deal with inflation that remained above target. Investors are now watching whether another increase could arrive in October or December. (Reuters)
That outlook could change quickly as new economic data arrives.
The latest jobs report was weaker than expected, which reduced market expectations for an immediate second consecutive rate increase. But investors still need to balance weaker employment signals against elevated inflation and energy prices. (Reuters)
The release of the Fed's September meeting minutes will therefore be closely watched for clues about how policymakers view the inflation-growth trade-off.
For U.S. stocks, the ideal scenario would be slowing inflation without a sharp deterioration in economic growth. That could allow the Fed to avoid further aggressive tightening while leaving corporate earnings relatively healthy.
Earnings Expectations Are High
Corporate earnings are another major test.
Third-quarter earnings season is beginning with companies such as PepsiCo and Delta Air Lines scheduled to report, followed by the major U.S. banks and a much broader group of companies. Analysts expect S&P 500 earnings to have increased by more than 30% year over year in the third quarter, according to LSEG IBES data cited by Reuters. (Reuters)
That is a strong forecast, but it creates a higher hurdle for companies.
When expectations are already elevated, merely beating earnings estimates may not be enough to drive a stock higher. Investors can also focus on revenue growth, margins, forward guidance and capital spending.
This is especially important because U.S. stocks have already enjoyed a substantial rally.
If companies deliver strong results and raise their outlooks, earnings could provide the fundamental support needed to offset higher yields. If results are merely in line with expectations, valuation concerns could become more prominent.
AI Spending Has Become a Market-Wide Question
The other major issue is artificial intelligence.
The 2026 stock-market rally has been closely linked to expectations surrounding AI investment. Hyperscalers and other large technology companies have been spending enormous amounts on data centers, computing infrastructure and related equipment.
That spending has benefited a wide range of companies beyond the major AI platforms themselves.
But investors now want evidence that the enormous capital expenditure is generating sufficient economic returns.
Nelson Yu, head of equities at AllianceBernstein, told Reuters that one of the most important issues during the upcoming earnings season will be capital-expenditure revisions from major hyperscalers, because those spending plans can affect a much wider chain of companies and sectors. (Reuters)
For investors, this makes AI capex an important market indicator rather than simply a technology-sector story.
A continued increase in spending could support semiconductor, networking, power, data-center and infrastructure companies. A sudden slowdown could have the opposite effect, particularly for stocks whose valuations already assume strong AI-related growth.
The November Midterm Elections Add Another Layer of Uncertainty
The U.S. midterm elections are scheduled for November 3, when voters will decide control of Congress.
Historically, markets have often performed better after election uncertainty clears. But the period before the election can still produce volatility, especially if investors begin pricing in a significant change in policy.
The current Republican Party controls the presidency, and a shift in control of Congress could affect expectations for taxes, regulation, government spending and other economic policies. (Reuters)
That does not mean investors should try to predict the election and trade around it.
In fact, historical evidence suggests that market performance around midterms is influenced by much more than election results themselves. Interest rates, economic growth and corporate earnings can remain the dominant forces.
What Could Support US Stocks in Q4?
Despite the risks, the bullish case has not disappeared.
The first support is corporate profitability. If earnings growth remains above expectations, stocks may be able to absorb higher Treasury yields.
Second, election uncertainty could diminish after November 3. Historically, that has coincided with stronger fourth-quarter market performance.
Third, the economy has not shown the kind of severe deterioration that would normally undermine corporate earnings. The recent weaker jobs data could also reduce pressure for another immediate Fed rate increase.
Finally, continued AI investment could sustain earnings growth across several technology and infrastructure industries.
The combination could allow the market's historical fourth-quarter strength to reassert itself—but only if bond yields stabilize.
What Investors Should Watch Now
For Indian investors tracking U.S. markets, the most important indicators over the next several weeks are:
10-year Treasury yield: A sustained move higher could pressure equity valuations.
Federal Reserve guidance: Investors need clarity on the path of interest rates.
Third-quarter earnings: Watch both results and forward guidance.
AI capital expenditure: Hyperscaler spending plans could influence the broader technology market.
November 3 midterm elections: Policy expectations may shift as voting approaches.
Energy prices and inflation: Higher energy costs could make the Fed's job more difficult.
Market breadth: Continued gains concentrated in a small number of large technology companies could indicate greater concentration risk.
For Indian investors, movements in U.S. equities can also influence global risk sentiment, technology stocks, the dollar and capital flows into emerging markets. However, India's domestic earnings, valuations, interest rates and macroeconomic conditions remain separate drivers.
Conclusion
U.S. stocks enter the fourth quarter with a strong historical tailwind, but spiking Treasury yields, high earnings expectations, the November midterms and the market's dependence on AI investment make 2026 different from a routine seasonal rally.
The S&P 500's nearly 13% gain so far this year gives investors a solid foundation, but it also means expectations are high. The next phase of the rally will likely depend on whether corporate earnings can continue to surprise positively while bond yields stabilize. (Reuters)
The key takeaway for investors is to watch the interaction between rates, earnings and AI spending, rather than relying on fourth-quarter seasonality alone.
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This article is for informational and educational purposes only and should not be considered investment advice.