S&P 500 closes at 7,686.14 on August 31, 2026 — Dow sheds 374 points but August still ends higher
All three major US indexes fell on August 31, 2026 and all three still finished the month higher. The Dow Jones Industrial Average closed down 374.09 points, or 0.7 percent, at 53,185.90, the Nasdaq Composite down 0.12 percent at 26,370.89, and the S&P 500 down 0.33 percent at 7,686.14. For August the Dow gained roughly 1.3 to 1.4 percent for a fifth consecutive winning month, while the S&P 500 rose about 2.4 to 2.5 percent and the Nasdaq about 3 to 3.5 percent, each the first monthly gain since May. The day's trigger was the resumption of direct US-Iran fighting near the Strait of Hormuz, which sent Brent crude back above 90 dollars a barrel and lifted energy shares 0.9 percent even as the indexes fell. Odds of a 25 basis point Fed rate increase in September rose to about 62 percent from roughly 40 percent a week earlier
The three lines
- Close — S&P 500 7,686.14 (−0.33%), Nasdaq 26,370.89 (−0.12%), Dow 53,185.90 (−374.09 pts)
- Month — Dow's fifth straight winning month; first up month since May for the S&P 500 and Nasdaq
- Driver — Hormuz fighting lifted oil; September Fed hike odds moved to about 62 percent
Key questions
- What were the US index closes on August 31, 2026?
- **S&P 500 7,686.14, Nasdaq Composite 26,370.89, Dow Jones Industrial Average 53,185.90.** The moves were −0.33 percent, −0.12 percent and −374.09 points (−0.7 percent) respectively. All three fell, but **the sizes differ in a way that describes the session.** The Dow fell hardest and the Nasdaq barely moved. The Dow is a **price-weighted** index of 30 stocks — it sums share prices and divides — so a few high-priced names swing it. The Nasdaq is technology-heavy and was less exposed to the day's rotation into energy. For reference, the S&P 500's August 28 close was 7,711.76, so the day's decline was **25.62 index points**.
- Was August up or down overall?
- **All three indexes rose over the month.** The Dow gained about **1.3 to 1.4 percent**, its **fifth consecutive winning month**. The S&P 500 added roughly **2.4 to 2.5 percent** and the Nasdaq about **3 to 3.5 percent**, each the **first up month since May**. Monthly figures differ by a decimal place across outlets because the prior month-end reference and the rounding convention are not standardised, which is why this page gives ranges rather than picking one. The direction is what holds: **the last day was down and the month was up.** August was not smooth — a 30-year Treasury yield above 5.3 percent in mid-month and reports of a second round of semiconductor tariffs late in the month both knocked the indexes — but neither reversed the month.
- What does a 62 percent chance of a September hike mean?
- **It is a number derived from federal funds futures prices, not a poll of Fed officials.** As of August 31 the market-implied probability of a **25 basis point increase** at the September meeting was about **62 percent**, up from roughly 40 percent a week earlier. What moved it was **Fed chair Kevin Warsh's Jackson Hole remarks** on inflation proving persistent, which pushed the figure from the 30s to about 56 percent within a day, and then August 31's oil spike added the rest. The chain runs quickly: **Middle East event → oil higher → inflation expectations up → rate-hike odds up**, all inside one session, because energy prices feed directly into inflation readings. How the number is computed is covered in "A 56 percent chance of a rate hike — this number comes from futures prices, not a vote."
On the last trading day of August, all three major US indexes fell. And all three still finished August higher.
1. The session
| Index | August 31 close | Change |
|---|---|---|
| S&P 500 | 7,686.14 | −0.33% |
| Nasdaq Composite | 26,370.89 | −0.12% |
| Dow Jones Industrial Average | 53,185.90 | −374.09 pts (−0.7%) |
| Energy sector | — | +0.9% |
Three indexes moved the same direction but the Dow fell hardest. It is a price-weighted index of 30 stocks, summing share prices and dividing, so a few expensive names move it disproportionately. The Nasdaq, at −0.12 percent, was nearly flat.
The line that summarises the day is the last one: only energy rose.
2. The month
| Index | August gain | Note |
|---|---|---|
| Dow | about 1.3–1.4% | Fifth straight winning month |
| S&P 500 | about 2.4–2.5% | First up month since May |
| Nasdaq | about 3–3.5% | First up month since May |
The ranges are deliberate. Outlets disagree by a decimal place because the prior month-end reference and the rounding convention are not standardised. Rather than picking one figure, this page leaves the spread visible.
August was not a calm month. Mid-month the 30-year Treasury yield reached its highest since 2007 at 5.31 percent; late in the month came reports of a second round of semiconductor tariffs. Neither was enough to turn the month negative.
3. The trigger — Hormuz
US forces struck Iranian rocket launchers on Larak Island; Iran struck US bases in Jordan. It was the first direct exchange since July 29 ("US and Iran exchange fire on August 31, 2026").
The market's transmission chain was short.
| Step | What happened |
|---|---|
| ① Event | Fighting resumes near the Strait of Hormuz |
| ② Oil | Brent crude back above $90 |
| ③ Sectors | Energy +0.9%, most others lower |
| ④ Rates | September hike odds to about 62% |
Step ④ is the one to hold onto. Oil feeds directly into inflation readings, which is why a Middle East event moves rate expectations the same day.
4. The 62 percent
| Point in time | Odds of a 25bp September hike |
|---|---|
| A week earlier (~Aug 24) | about 40% |
| August 28 (after Warsh) | about 56% |
| August 31 | about 62% |
This is implied from federal funds futures prices, not a tally of Fed votes. It reflects where money is positioned, not what has been decided.
What moved it first was Fed chair Kevin Warsh's Jackson Hole remarks on persistent inflation, which took the figure from the 30s to about 56 percent within a day ("Warsh's first Jackson Hole speech, August 28, 2026"). August 31's oil spike added the remaining six points.
The calculation itself is covered in "A 56 percent chance of a rate hike — this number comes from futures prices, not a vote."
5. What is still unresolved
- Monthly figures — Dow 1.3–1.4%, S&P 500 2.4–2.5%, Nasdaq 3–3.5%. No single value was selected.
- Single names — Reports linking Amazon's 3 percent fall to an expected FTC advertising lawsuit, and a 3.5 billion dollar Nvidia investment in MediaTek, were not verified against primary sources here.
- Energy sector — The 0.9 percent gain comes from reporting; constituent detail was not checked.
- Rates — 62 percent is an August 31 value. Employment and inflation data before the September meeting will move it.
- Next — The monthly employment report in the first week of September, and inflation data the following week, are the next inputs.
Sources
- CNBC — Dow tumbles 370 points after U.S. strikes Iran, but index posts fifth straight winning month
- Yahoo Finance — Dow, S&P 500, Nasdaq slip but cap winning month for stocks
- The Motley Fool — Market Indexes Slip to Close Out a Winning, Turbulent August
- FXStreet — August was three good days for the Dow Jones Industrial Average
- The Hill — Oil prices surge after US attack on Iran's Larak Island