S&P 500 September outlook: Key risks investors should watch as stocks near record high

S&P 500 enters September near a record high. Investors should watch Fed rates, Treasury yields, VIX, sentiment, support levels and earnings growth.

The S&P 500 is entering September near a record high. The index has remained within 2% of its record high of more than 7,800 throughout August. The S&P 500 is also up 12.72% so far in 2026, showing that stocks have had a strong year. Other major US indexes are also up strongly this year. The Nasdaq Composite has gained 14.23%, while the Dow Jones Industrial Average is up 10.72% year to date.

S&P 500 enters September near a record high. (REUTERS/Jeenah Moon/File Photo) (REUTERS)

The big question now is whether the S&P 500 can continue its gains in September. Wall Street is watching several risk signals as the index starts the new month close to record levels. However, analysts say the usual September weakness does not automatically mean stocks will fall this year, according to Quartz.

S&P 500 September outlook

September has a bad reputation among stock investors. It is widely known as the worst month of the year for stocks, based on historical market performance. But some current conditions suggest investors may not need to expect a major September sell-off.

One market strategist sees a more positive seasonal setup for September. Ryan Detrick, chief market strategist at Carson Group, said the current conditions could reduce concerns about the traditionally weak September period, according to Benzinga.

History has been positive when August ends with gains and the S&P 500 is up 10% to 17.5% for the year. Those conditions match the market's situation in 2026. In such years, September has produced an average gain of 1% since World War II, according to data cited by Detrick. The historical trend also looks positive for the rest of the year. When the same conditions occurred, the final four months of the year ended higher in 10 out of 11 cases. The average gain during those four months was 5.6%.

S&P 500 key level to watch

But investors still need to watch the midterm-election-year effect. Detrick warned that midterm election years can create more market turbulence during August and September, meaning historical seasonal strength does not remove the risk of short-term swings. The 7,610 level is an important support level for the S&P 500. Detrick identified 7,610, which was the S&P 500's June 2 peak, as a key level investors should watch. A move toward or below this level could become important for the market's direction.

Stock market volatility

Market volatility is another warning signal. CNBC's Mike Santoli pointed to the CBOE Volatility Index, or VIX, which has fallen below 15. The VIX is closely watched as a measure of expected stock-market volatility, according to CNBC. Santoli sees the very low VIX as a sign of complacency. He described the low volatility reading as “eerie complacency.” The reading stands out because seasonal patterns normally lead to higher volatility around this time of year.

Treasury yields and Fed rates

Interest rates are becoming another major concern for investors. The 10-year Treasury yield has moved back above 4.7%, adding another pressure point for stocks because higher bond yields can make equities less attractive and raise borrowing costs.

The Federal Reserve's next move is now a key market question. Fed Chairman Kevin Warsh used his Jackson Hole appearance on Friday to signal that the committee sees short-term rate increases as the appropriate response to persistent inflation. He also indicated that a rate increase could come soon.

Markets are almost evenly split on the possibility of a September rate hike. Fed-funds futures were pricing in roughly a 50% chance of a rate increase in September after Warsh's speech. That uncertainty could make investors more cautious. Santoli said when the odds of a rate hike are almost evenly split weeks before a Fed meeting, investors may be less willing to take on additional risk.

S&P 500 earnings risk

Investor sentiment is also sending a warning. John Kolovos of Macro Risk Advisors said the latest sentiment reading was broadly unchanged but had moved in a worrying direction, according to Quartz. Traditional investor surveys show too much bullishness. Surveys such as Investors Intelligence are showing a high number of bulls, suggesting many investors are already optimistic about the market.

Real-time market data is also pointing to complacency. This means investors may be feeling too comfortable despite the risks facing stocks, according to Kolovos' assessment cited by Quartz. Another risk is that a small number of companies are responsible for a large part of the market's profit growth. Charles Schwab's analysis found that Nvidia and Micron alone are responsible for roughly one-third of the S&P 500's total 2026 profit growth.

The concentration becomes even clearer when the biggest companies are counted together. The 10 largest contributors to earnings growth account for about two-thirds of total 2026 profit growth, according to Charles Schwab's analysis cited by Quartz.

This means investors should watch more than just the S&P 500's record level in September. They should pay attention to the 7,610 support level, VIX volatility, Treasury yields, Fed rate decisions, investor sentiment and the heavy dependence on a small group of companies for earnings growth.

Overall, the September outlook is mixed. Historical data offers some reasons for optimism because the current 2026 setup has previously been followed by gains. At the same time, low volatility, high investor confidence, possible Fed rate hikes, rising Treasury yields and concentrated earnings growth are important risks for the S&P 500.