US core CPI rises 0.3% in August as wireless service prices post a record 5.9% jump

A surge in wireless phone service costs turned into an inflation headline. The US Bureau of Labor Statistics (BLS) said wireless telephone service prices jumped 5.9% in August 2026, the largest one-month increase ever recorded for the category. The move contributed disproportionately to a 0.3% month-over-month increase in core CPI. The headline Consumer Price Index rose 0.4% in August on a seasonally adjusted basis and was up 3.4% year over year. Core CPI, which excludes food and energy, increased 2.4% from a year earlier. Wireless services carry an estimated 1.3% to 1.4% weight in the CPI basket, giving the category enough heft for sharp swings to show up in core inflation. The backdrop to August's spike traces to a BLS methodological overhaul in July 2025. At that time, the agency shifted to more comprehensive secondary data sourced directly from carriers and Mobile Virtual Network Operators (MVNOs), and began using hedonic regression models to adjust prices for changes in the quality of services consumers receive. Since that change, volatility has become more visible. Wireless service prices fell 3.3% in December 2025, the steepest drop since March 2017, before rebounding 2.2% in May 2026 as major carriers adjusted pricing. August's 5.9% surge was far larger than either move. Communications overall represents about 3.2% of the CPI basket, with wireless services the dominant subcategory. That structure magnifies wireless-driven swings in the broader communications index and adds complexity for economists trying to separate inflation driven by underlying cost pressures from inflation that reflects improved measurement capturing pricing dynamics that may have long existed. For markets and monetary policy, the key issue is whether the Federal Reserve treats the wireless spike as signal or noise. If officials judge the August core CPI reading to be boosted by a methodology-related outlier, they may discount it. If it is interpreted as evidence of persistent services inflation, expectations for rate cuts could be pushed further out. Telecom equities face a mixed read-through. The ability to raise prices points to pricing power that can support margins, but sustained increases could accelerate subscriber churn among cost-sensitive customers. Competition between traditional carriers and MVNOs may intensify if consumers become more aggressive in searching for cheaper plans.