US inflation rose to 3.7%: why it matters for stocks

On October 14, 2026, the US Bureau of Labor Statistics (BLS) released September inflation. The number came in above expectations — and markets felt it the very next day. Three questions: what happened, how markets reacted and what to watch next.

BLSFederal ReserveUSA

What happened

Consumer prices rose 3.7% over the year — up from 3.4% in August (BLS). Put simply: a purchase that cost $100 a year ago now costs about $103.70.

The biggest driver was gasoline: it rose 9.1% in a single month and accounted for more than half of the monthly increase.

Two numbers: 3.7% and 2.6%

Every inflation report has two headline figures:

• Headline inflation — everything, including food and energy: 3.7% over the year, 0.6% for the month;
• Core inflation — excluding food and energy, the most volatile prices: 2.6% over the year, 0.3% for the month.

Gasoline can jump sharply in one month, so the US central bank (the Fed) pays more attention to core prices — the longer-term trend. The problem is that core prices also rose faster than expected this time: economists expected 0.2% for the month, the actual figure was 0.3% (Trading Economics).

Why this matters for stocks

To slow price growth the Fed raises its rate — the price of borrowing. On September 16, 2026 it raised the target range by 0.25 points to 3.75–4.00% (Fed statement). When borrowing gets more expensive, growth costs companies more, and investors are willing to pay less for future earnings — stocks come under pressure. We cover the basics in our macro primer.

How markets reacted

Korea ExchangeSouth Korea

• October 15: South Korea's Kospi fell 7.6% in a day, led by a chip-stock sell-off. According to the Korea Herald, one of the reasons was concern that the Fed could raise rates again after the inflation data (Korea Herald);
• As of October 14, CME FedWatch put the probability of a hike at the October meeting at about 51.5% — up from 23.8% a day earlier (InvestmentNews). One report more than doubled the market's expectation.

What to watch next

• October 27–28 — the Fed meeting and its next rate decision (Fed calendar);
• November 10 — BLS releases October inflation.
• The short lesson: inflation is the market's weather. When prices speed up, rate expectations shift, and stocks respond — even when no company has any news.

For information only — not investment advice. Figures refer to the dates shown; check the sources for current values.