September 24, 2026

Tech Stocks Sold Off. Rising Interest Rates and Rebounding Oil Prices Weigh Down the Market | 9/23 US Stocks

Ratahi’s Daily Market Notes
US Market Report: September 23, 2026

Good morning.
I’m Ratahi, your stock-trading heroine.

On September 23, all three major US stock indices fell.
The NASDAQ was down 1.13%.
Although it had hit record closing highs for two consecutive days leading up to this, it pulled back today.
The S&P 500 fell 0.75% and the NY Dow fell 0.68%.
Furthermore, the semiconductor SOX index, which had been strong until the previous day, also fell 1.23%.

The key points for the day were
strong US economy → rising interest rates
oil prices → rebound
AI/semiconductor stocks → selling pressure
—a combination of factors moving in the opposite direction from the previous days.

And starting today, September 24, the Japanese stock market will resume trading for the first time since September 18. While the Japanese market was closed, the NASDAQ hit a record high in the US, but on the 23rd, tech and semiconductor stocks pulled back against a backdrop of rising interest rates and rebounding oil prices.
How will the Japanese market incorporate the
US stocks, US interest rates, oil, and exchange rates that moved while it was closed? In today’s Tokyo market, I want to pay close attention to the reaction, especially in semiconductor stocks.

Major Markets

The main factor behind the stock decline is an “economy that is too strong”

The major material for the day was the September US PMI.
The S&P Global US Composite PMI flash reading was 58.4.
It rose from 56.0 in August, reaching its highest level in about five years, since July 2021.
The Manufacturing PMI was 57.0, and the Services PMI was 58.7.
The strength of business activity was confirmed once again.
Normally, one would think “a strong economy equals a positive for stocks.”

However, in the current market, the strength of the economy is perceived in the form of
inflation being hard to lower
↓
possibility of further Fed rate hikes
↓
rising US Treasury yields
.

In fact, the 10-year US Treasury yield rose to around 5.10%, its highest level since 2007.
Fed Governor Barr also mentioned the possibility that additional rate hikes might be necessary.
The market-implied probability of a rate hike at the October FOMC rose to 71%.

In other words, the point this time is not that
“stocks were sold because the economy is bad,” but rather
“stocks were sold because interest rates rose due to a strong economy.”

Oil also rises again

Another weight on the market is oil.
WTI crude oil rose +1.81% to $92.16.
Brent crude oil rose to +3.86% at $103.08.
Until the previous day, the decline in oil prices had been a source of relief for the stock market.

However, on the 23rd, supply concerns were once again brought to the forefront, causing oil prices to rebound.
Since rising oil prices lead to concerns about corporate costs and inflation,
higher oil prices
+
US economic strength
+
rising interest rates
—these three factors simultaneously weighed on the stock market.

Semiconductor stocks also fell back

Selling also emerged in semiconductors, which had been driving the market until the previous day.
The SOX index was down 1.23%.
NVIDIA fell 1.47%, and AMD also fell 1.47%.

Given that the NASDAQ had also hit record highs for two consecutive days leading up to this, selling spread to tech and semiconductor stocks amid rising interest rates.

Meanwhile, Meta was up about +1%.
Expectations for the new AI assistant ‘Muse’ continue, so tech stocks have not collapsed across the board.
However, Alphabet was down 3.8%, and Amazon was down 2.2%.
Following the gains led by AI-related stocks until the previous day, the divergence between individual stocks has also widened.

Not only the indices but the ‘underlying components’ were also weak

On this day, out of the 11 sectors in the S&P 500, 10 sectors declined.
In particular, Utilities fell 1.88%, and Communication Services fell 1.89%, showing significant declines.
On the other hand, against the backdrop of rising oil prices, Energy was the only sector to rise, up 1.04%.

In other words, it can be seen that on the 23rd, it was not just the NASDAQ that fell, but rather a day where selling was dominant across the entire market.

It is easier to understand when looking at the differences from the previous day

On September 22nd,
lower oil prices
+
stable interest rates
+
higher semiconductor stocks
caused the NASDAQ to hit record highs for two consecutive days.

However, on the 23rd, it shifted to
rebounding oil prices
+
rising interest rates
+
semiconductor pullback
.

In just one day, the direction of the factors driving the stock market has almost completely reversed.

That is precisely why it is becoming important to check these three as a set, rather than just looking at the NASDAQ or SOX:
oil
US 10-year Treasury yield
semiconductor stocks
.

Points to check going forward

First, we want to focus on whether the US 10-year Treasury yield will rise further from the 5% level.
Next, whether Brent crude oil will remain above $100.
And finally, whether buying will return to AI and semiconductor stocks despite rising interest rates.
Can the NASDAQ and semiconductor stocks, which were strong until yesterday, continue to chase higher prices even in a rising interest rate environment?
When looking at US stocks going forward, we want to pay attention not only to stock prices but also to the movements of interest rates and oil.

And today, September 24th, the Japanese market will resume trading after being closed for a holiday.
In the US market while it was closed, the NASDAQ pulled back after hitting a record high, and the US 10-year Treasury yield and oil prices also moved significantly.
Therefore, for today’s Japanese stocks, we are also watching
the price movements of US semiconductor stocks
US 10-year Treasury yields
oil prices
dollar-yen
to see how the Japanese market will price these in.
In particular, we want to check the reaction of semiconductor and AI-related stocks, which were driving the Nikkei 225 significantly before the holiday.

Summary

On September 23rd, US stocks saw major indices fall across the board:
NASDAQ -1.13%
S&P 500 -0.75%
NY Dow -0.68%
SOX -1.23%
.
The background was not a weak economy.

The US economy being stronger than expected fueled expectations for rate hikes, pushing the US 10-year Treasury yield up to the 5.1% level. Furthermore, the rebound in oil prices weighed on the stock market.

Until the previous day,
lower oil prices and stable interest rates → higher semiconductor stocks
had been supporting the market.

On the 23rd, that combination reversed.

Precisely because the NASDAQ is at record-high levels, we want to look not only at stock prices but also at
“which way oil and interest rates are heading” together.

— Stock Activity Heroine Ratahi-chan

References

S&P Global “S&P Global US Flash PMI” (September 23, 2026)
Reuters “Wall Street falls as oil rebounds, Middle East tensions simmer” (September 23, 2026)
Reuters “Oil settles up around 4% as Iran’s president vows to never surrender” (September 23, 2026)
Reuters “Fed’s Barr says further rate hikes will likely be needed” (September 23, 2026)
Yahoo Finance / MT Newswires “Nasdaq Retreats From Record, Yields Surge Amid Mounting Rate Hike Bets” (September 23, 2026)
Nasdaq “PHLX Semiconductor Sector Index (SOX)” (September 23, 2026)
Fidelity “S&P 500 Sector Performance” (September 23, 2026)
Japan Exchange Group “List of Business Hours and Holidays”

Disclaimer

*This report is intended to provide information to deepen understanding of the market and does not recommend the buying or selling of any specific financial product. Please make investment decisions at your own responsibility.

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