The usual fourth-quarter case for stocks begins with the calendar. Since 1945, the S&P 500 has gained an average 4.2% in the final three months of the year, and 6.4% in midterm-election years, according to LSEG data cited by Reuters. This year also arrives with the index up about 13% and analysts expecting third-quarter earnings to rise roughly 30%. The obstacle is that the US 10-year Treasury yield has reached 5.34%, its highest level in 24 years. A seasonal tailwind now has to overcome a discount rate that can compete directly with equity returns.
Strong profit forecasts are carrying a larger valuation burden
The S&P 500 ended the week only about 1% below its record, even as bond yields rose and investors confronted another quarter of heavy artificial-intelligence spending. High expected earnings growth can justify high prices if cash generation follows. It offers less protection when growth rests on capital expenditure whose revenue arrives years later. The market is therefore asking two questions at once: whether profits can meet unusually strong forecasts, and whether those profits deserve the same multiple when a long government bond yields more than 5%.
The relevant contest is cash flow against the risk-free rate
Seasonality is an observed pattern, not a financing mechanism. Companies with pricing power, modest refinancing needs and visible free cash flow can still earn a premium over government bonds. Long-duration growth companies and leveraged businesses face a stricter test because more of their value depends on distant earnings. This does not make a fourth-quarter advance impossible. It makes market breadth and earnings quality more important than the index headline. A rally led by a few balance-sheet-rich groups would be less persuasive than one supported by improving margins and cash conversion across sectors.
Follow guidance, buybacks and the term premium
The decisive evidence will be management guidance, capital-spending commitments, free-cash-flow conversion and the number of companies raising rather than merely meeting estimates. In rates, watch whether the 10-year yield is being driven by stronger real growth or a higher term premium linked to inflation and fiscal risk. The former can coexist with rising profits; the latter compresses valuations without providing companies more demand. Investors should treat fourth-quarter seasonality as a starting prior, then require earnings and financing conditions to validate it.
How to use this analysis
Source and verification note
The reporting base for this article is Reuters: bond yields, earnings and the fourth-quarter equity test and US Treasury: daily Treasury par yield curve rates. The link is provided to the source page or release so readers can check the reporting period, definitions and later revisions. Figures are not extended beyond the source's geographic or institutional scope, and forecasts remain labelled as expectations until an official release records the outcome.