Semiconductor stocks plunge as US CPI hits 3.7%—Why falling interest rates aren't enough to feel safe and the next criteria for judgment

Thursday, October 15, 2026, 5:50 AM | Market Compass

Key Takeaway

Following the CPI release, the market is reassessing price increases and the valuation of growth stocks.

The SOX index fell 4.30%, and the VIX rose 10.34%. Meanwhile, the final reading for the US 10-year Treasury yield dropped to 5.190%.

This is a phase where you should not feel reassured by the final interest rate figure alone, but rather judge based on a combination of price breakdowns, the scope of stock declines, and corporate earnings and financing.

What you will learn in this article

• What part of the CPI weighed heavily on the market?

• The meaning behind the coexistence of falling stocks and falling interest rates.

• Conditions to check with today’s Japanese stocks and tonight’s indicators.

• Responses that individuals and companies should decide on in advance.

5:50 AM Market

• Nikkei Large Futures: 66,480 yen. Down 1,264.29 yen against the latest spot price of 67,744.29 yen.

• S&P 500: 7,718.94, down 1.11%.

• NASDAQ 100: 29,950.82, down 2.02%.

• US 10-year Treasury yield: 5.190%. The rate of change on the screen is down 0.52%, not basis points.

• Dollar-Yen: 158.341 yen, up 0.02%.

• NY Gold: The target value for the regular market could not be confirmed in the image.

• WTI Crude Oil CME: $95.06.

Supplementary indicators are the SOX at 11,684.38, down 4.30%, and the VIX at 16.86, up 10.34%.

Is the CPI just about energy?

The US September CPI released on October 14 showed a 0.6% increase month-over-month and a 3.7% increase year-over-year. The year-over-year figure rose from 3.4% in August. 2026 M09 Results

Core CPI, excluding food and energy, rose 0.3% month-over-month and 2.6% year-over-year.

Gasoline prices rose 9.1% month-over-month, accounting for more than half of the total monthly increase. Housing costs also rose 0.4% month-over-month. 2026 M09 Results

In other words, the major factor pushing up the headline CPI this time was energy.

However, this does not mean that price increases would disappear if energy were excluded.

The 0.3% month-over-month increase in core CPI is the same as in August. It cannot be said that “core inflation accelerated from the previous month.” 2026 M09 Results

On the other hand, even if the year-over-year comparison remains stable, the burden of living costs persists if monthly increases continue.

Reuters reported that higher-than-expected inflation heightened concerns about additional interest rate hikes, putting pressure on AI-related stocks and others. In this article, the difference from market expectations is based on this report, and I will not independently set unconfirmed forecast values. Reuters

What is important in the analysis from here on is to distinguish between ‘current prices’ and ‘future prices’.

This CPI reflects September prices. October crude oil trends will not be fully reflected in these figures.

If WTI remains around $95, the market will also consider the burden for the following month.

Even after reading through a single price announcement, the monitoring of energy does not end.

Why did stocks sell off heavily even though interest rates fell?

The US 10-year Treasury yield this morning is 5.190%.

However, the chart in the image also shows a high of 5.329%. It can be read that interest rates rose during the period and then fell afterward.

The exact time the high was reached and the reason for the subsequent decline cannot be determined from this image alone.

Therefore, I will not simplify this by saying “interest rates kept rising because the CPI was strong” or “the CPI was not a problem because rates fell at the end.”

Long-term interest rates do not move solely based on the outlook for policy rates. They reflect prices, growth, bond demand, and more.

In addition to that, stocks reflect corporate earnings and current stock valuations.

If the movement to buy bonds due to anxiety intensifies, a decline in interest rates and a drop in stock prices can occur simultaneously.

While the extent of this factor is not yet certain, it is a hypothesis that should be kept in mind for judgment.

What we need to look at is whether the decline in interest rates stems from ‘expectations of lighter cost burdens’ or ‘anxiety over profits and growth’.

We will consider the stock market’s reaction in conjunction with corporate outlooks.

Semiconductor decline: Distinguishing between AI demand and investment profitability

The SOX index fell 4.30%, and the NASDAQ 100 also dropped 2.02%.

In sectors with strong growth expectations, re-evaluations are becoming significant.

However, one cannot say that ‘AI demand has disappeared’ based on this single day’s decline.

Growth in demand and the ability of that investment to generate sufficient profit or cash are two different things.

For example, in companies increasing capital expenditure, even if orders and sales are rising, payments may come first, and it may take time to recover the costs.

If borrowing is high, the worsening of refinancing conditions also becomes a burden.

What I want to confirm in upcoming earnings reports is the combination of sales growth, profit margins, capital expenditure, operating cash flow, and financing.

Operating cash flow is an indicator that shows how much cash has been generated from core business operations.

We must not group everything under the name ‘AI-related’ but instead look separately at companies that generate profits and those that require funds for upfront investment.

VIX rise: Distinguishing between increased caution and the actual level

The VIX rose 10.34% to 16.86.

The VIX is an indicator calculated from S&P 500 option prices that shows the market’s expectation for future price movements.

While the rate of increase is large, I would not call a level of 16.86 a full-blown panic.

What we can confirm is that caution regarding price volatility has intensified compared to the previous day.

From here on, we will check whether the stock price decline and VIX rise continue, or if the VIX settles down when there is a rebound.

It is also necessary not to automatically extrapolate a single day’s large change into a long-term crisis.

Two paths reaching Japanese stocks and households

Nikkei futures are down approximately 1,264 yen compared to the cash index.

This is a strong warning sign for today’s cash market, but it is not the final figure for the opening or closing price.

The decline in overseas semiconductor stocks could impact the valuation of related Japanese companies and expectations for capital investment.

Meanwhile, crude oil at $95.06 could lead to a burden on imported fuel and logistics costs.

The dollar-yen is at 158.341 yen, with a small change from the previous day on the screen. It cannot be said from this display that the yen has depreciated rapidly.

However, it also cannot be said that the yen has strengthened significantly enough to offset the burden of crude oil.

Actual costs are related to forward exchange contracts, long-term agreements, and price revision timing.

Not every company or household faces the same burden the day after market prices rise.

Companies look at their own contracts and reflection timing, while households look at rate revisions and monthly expenditures.

It is necessary to translate market changes into your own payments.

Three future scenarios and conditions for switching

The following are monitoring criteria set for this article, not predictions or established market turning points.

Using the US 10-year Treasury and WTI in the normal market, we confirm the closing price and the continuity of the next day rather than temporary fluctuations.

1. Main: Inflation vigilance remains, and stock selection continues

This is the case where the US 10-year Treasury remains around 5.15–5.30% and WTI remains around $90–$96, and corporate profit outlooks do not collapse significantly.

In this case, we anticipate a development where companies that can maintain profits and capital are selected rather than stock prices recovering all at once.

We will check if the decline in semiconductor stocks stops and if the VIX settles down.

2. Upside: Crude oil settles, and profit maintenance can be confirmed

This is the case where WTI returns to below $95 and further declines toward $90, while demand and profit margins are maintained in earnings reports.

If the US 10-year Treasury yield remains below 5.15% and stocks recover, the hypothesis of reduced burden will strengthen.

The confirmation condition is that “falling interest rates and rising stock prices must coexist.”

If only interest rates fall while stock prices continue to decline, I will withhold an upward revision judgment.

3. Downside: Concerns over prices, financing, and profits overlap

This is the case if WTI settles above $96, the US 10-year Treasury yield returns to over 5.30%, and corporate outlooks deteriorate.

I will also add the condition of whether the VIX remains above 20 as an additional monitoring criterion in this report.

However, even if interest rates fall, it is not necessarily a cause for relief.

If stock prices fall broadly, profit outlooks decline, and financing becomes difficult, I will consider this a downside scenario driven by growth anxiety.

I will switch my judgment based on what stock prices, crude oil, and corporate financial conditions indicate, rather than just the direction of interest rates.

Impact on individuals—Do not use CPI as a signal for buying and selling

Rather than linking this result directly to a single trading decision, I will check whether my assets are overly concentrated in the same growth expectations and whether necessary living expenses are insulated from market fluctuations.

Even if you hold multiple index products, the top holdings may overlap.

What matters is not the number of products, but which companies and sectors you are actually dependent on.

For bonds, consider not only the stated yield but also the maturity, price fluctuations upon mid-term sale, and exchange rates separately.

The yield on dollar assets and the ability to stably pay for living expenses in yen are not the same thing.

In household finances, keep in mind that even if the inflation rate slows in the future, prices that have already risen may not necessarily return to their original levels.

Check actual expenditures and fixed costs on a monthly basis.

Impact on companies—Look at procurement costs and sales outlooks simultaneously

If you separate high crude oil prices as a purchasing issue and falling stock prices as an investor issue, you will overlook the risk of demand and costs changing simultaneously.

Sales should check orders and price pass-through, purchasing should check material and logistics costs, and finance should check exchange rates and funding.

For management, we provide the combined impact on profits and cash flow.

For example, we decide that ‘if crude oil stays above $96 for several business days and orders from major customers weaken, we will consolidate the impact on costs, sales, and cash flow within X business days.’

We even clarify who will organize the data and when it will be passed to the approver.

Increasing inventory also ties up cash while reducing supply anxiety.

We evaluate inventory days, alternative procurement periods, and payment terms together.

Attach your company’s decision deadlines to market figures.

That is the implementation that turns information gathering into decision-making.

Five factors to check going forward

• US PPI at 21:30 today, the 15th: Price pressure on the corporate side. bls.gov

• US Retail Sales Advance Report at the same time: Distinguishing between demand and sales growth due to price increases. Release Schedule

• Import/Export Prices on the 16th at 21:30: Changes in import costs. bls.gov

• Earnings profit margins, cash flow, and investment plans: Is growth generating cash?

• Semiconductor stocks, VIX, US 10-year Treasury, and WTI: Will caution subside, or will the stock decline spread?

Reconfirm the schedule with the official calendar on the day.

Conclusion

The market after the CPI is questioning not only inflation but also whether companies can maintain profits and cash flow in that environment.

Even though the final reading of the US 10-year Treasury yield fell, the significant drop in the SOX index and the rise in the VIX remained.

The judgment that ‘it’s safe because interest rates have fallen’ cannot fully explain this combination of events.

Next, we will check for a stabilization in crude oil, the maintenance of corporate profits, and a broadening of the stock price rebound.

We will observe whether those conditions are met to adjust individual cash management and corporate responses.

Which of these are you most concerned about?

1. Decline in semiconductor stocks 2. Prices and cost of living 3. Corporate profits and financing

About the Author

Yoji Ohashi | Reading risks and creating criteria for judgment

After working in manufacturing, facilities, safety, global EHS, and corporate crisis management, I am currently engaged in ERM/BCP consulting. I interpret changes in markets, disasters, supply chains, and daily life to share ‘criteria for judgment’ that help individuals and companies act without hesitation.

Reference Information

Market figures: Attached ‘World Stock Prices’, confirmed October 15, 2026, at 5:49, 5:50 version.

This article is for informational purposes only and is not investment advice recommending the purchase or sale of specific products. Figures are as of the time of the attached image, and the reference time for information is October 15, 2026, 5:50 (JST). Scenarios and monitoring criteria are based on the author’s analysis and do not guarantee the future.