The Reference Time Is 2026-09-13 at 21:01 Korea Time.
Wall Street rebounds after 4 days of declines: Why the S&P500 and Nasdaq rose despite tensions involving Iran# Wall Street rebounds after 4 days of declines: Why the S&P500 and Nasdaq rose despite tensions involving Iran
U.S. stocks rebounded on 2026-09-11 (local time) despite continuing tensions in the Middle East surrounding Iran. The S&P500 gained 0.86%, the Nasdaq rose 0.96%, and the Dow Jones index advanced 0.98%. However, it would be premature to interpret a single day's rebound as evidence that the risks have disappeared. International oil prices fell that day but remained sharply higher for the week, while U.S. inflation continued to pose a concern ahead of the Federal Reserve's September interest rate decision.
The reference time is 2026-09-13 at 21:01 Korea time.
How Much Did U.S. Stocks Rise?
On September 11, all three major U.S. stock indexes closed higher. The gains marked a rebound from the preceding downward trend.
| Index | September 11 Closing Level | Daily Change |
|---|---|---|
| S&P500 | 7,656.98 | +0.86% |
| Nasdaq Composite | 26,333.04 | +0.96% |
| Dow Jones 30 | 52,573.29 | +0.98% |
The S&P500 gained 65.28 points, the Dow Jones index rose 509.19 points, and the Nasdaq advanced 251.31 points.
The weekly picture, however, tells a different story. Over the week, the S&P500 fell 0.8%, the Nasdaq declined 0.7%, and the Dow Jones index dropped 1.6%. Friday's gains alone might suggest that the market had staged a strong turnaround, but the indexes had not fully recovered the losses accumulated over the preceding days.
In other words, the move is better understood as a stock market rebound triggered by a temporary easing in oil prices amid persistent pressures, rather than a rally driven by the end of Middle East risks.
Why Did Stocks Rise Despite Continuing Tensions Involving Iran?
The most notable development in the stock market on September 11 was the decline in international oil prices. Although concerns about supply disruptions in the Middle East persisted, Brent crude prices fell by nearly 3% that day.
When oil prices fall, concerns that transportation and raw material costs for businesses and energy expenses for consumers could rise further may temporarily ease. Recently, a key market concern has been not only the situation in the Middle East itself but also the possibility that rising oil prices could push U.S. inflation and long-term interest rates higher again.
That does not mean geopolitical risks have been resolved. As of September 11, international oil prices were still up approximately 9% for the week, and concerns remained about potential supply disruptions along major transportation routes in the Middle East.
Therefore, when assessing this rally, it is more accurate to consider not simply that stocks rose despite tensions involving Iran, but that a one-day decline in oil prices eased some of the pressures that had recently accumulated.
What Did the U.S. August CPI Reveal About the Stock Market?
The U.S. consumer price index for August rose 0.4% from the previous month and 3.4% from 1 a year earlier. Core consumer prices, excluding food and energy, increased 0.3% month over month and 2.4% year over year.
Energy price movements were also pronounced in the August inflation data. The energy index rose 2.1% from the previous month, while the gasoline index increased 3.9%. Higher gasoline prices made a substantial contribution to the monthly increase in the overall August consumer price index.
The important point is that inflation concerns did not disappear simply because stocks rose that day.
The monthly increase in the U.S. CPI was 0.1% in July, but it accelerated to 0.4% in August. According to the author's calculation, the monthly inflation rate increased by 0.3% percentage points.
By contrast, the annual increase in core CPI slowed by 0.1% percentage points, from 2.5% in July to 2.4% in August. This means headline and core inflation did not move exclusively in the same direction.
That is why it is difficult to characterize this CPI report simply as either worsening inflation or stabilizing prices. Monthly headline CPI inflation accelerated, while the annual core inflation rate slowed slightly.
Why Do Concerns About Interest Rate Hikes Persist Even Though Stocks Rose?
The U.S. Federal Reserve will hold its Federal Open Market Committee meeting on 15–16 in September. A policy decision announcement and press conference are scheduled for September 16.
Recently, a major market concern has been how rising oil prices and inflation data might influence the Fed's interest rate decisions. The stock market's gains on September 11 do not necessarily mean that monetary policy pressures have eased.
In fact, the inflation figures released that day showed that rising energy prices were already feeding into consumer prices. In August, the energy index increased 16.3% year over year, while the gasoline index rose 27.4%.
From the market's perspective, two factors need to be considered simultaneously.
The first is whether international oil prices rise again. Another sharp increase in oil prices could prolong inflationary pressure.
The second is what the Federal Reserve actually decides at its September meeting. Market expectations regarding the possibility of an interest rate hike may continue to change before the meeting, so projected probabilities should not be treated as confirmed outcomes.
Why Technology Stock Performance Also Matters in This Rebound
Although the gains on September 11 represented a broad rebound in the indexes, not every sector performed equally. Of the 11 sectors in the S&P500, 9 finished higher, with communication services and consumer discretionary stocks showing relatively strong performance.
Recently, Wall Street has not been driven solely by developments in the Middle East. International oil prices, U.S. Treasury yields, artificial intelligence-related investment, and corporate earnings are all being reflected in stock valuations simultaneously.
As a result, even when geopolitical tensions persist, strong earnings from individual companies or strength in particular industries can lift the indexes. Conversely, even if tensions in the Middle East ease, a sharp rise in interest rates or weakness among major technology stocks could put renewed pressure on the market.
This is why the market session on September 11 cannot be adequately explained by the simple formula that continuing tensions involving Iran automatically mean falling U.S. stocks.
What Should Investors Watch on the Next Trading Day Rather Than Focusing Only on Friday?
To assess what may happen next, it is useful to examine three factors in sequence.
The first is international oil prices. Even though Brent crude fell approximately 3% during the session on September 11, its weekly gain remained substantial. If conditions surrounding Middle Eastern transportation routes and supply disruptions deteriorate again, oil price volatility could increase.
The next factor is U.S. Treasury yields. During the recent correction in U.S. stocks, rising long-term interest rates, as well as inflation, weighed on the market. If higher oil prices reignite inflation concerns, it will also be necessary to monitor the bond market's response.
The final factor is the Federal Reserve meeting scheduled for 15–16 in September. The actual policy decision and the Fed's explanation matter more than current market expectations. Beyond the interest rate decision itself, the Fed's assessment of future inflation and economic conditions could influence the stock market's next direction.
The latest Wall Street rebound can be summarized in one sentence: While tensions surrounding Iran continued, a one-day decline in oil prices and a modest easing of risk aversion in U.S. equities helped all 3 major indexes rebound, but weekly losses and inflation and interest rate pressures remained unresolved.
※ This article is provided for informational purposes to help readers understand market developments and does not constitute investment advice or a recommendation to buy any particular stock or asset. Readers are responsible for their own final investment decisions and the associated risks.