The news: The US ad market grew just 1.3% YoY in September, according to Guideline’s updated US Ad Market Tracker. The market has only expanded 1.7% year-to-date, according to Mediapost’s analysis of Guideline’s data.

Zooming in: September’s modest growth highlights how much the ad market benefited from major sporting events and other tentpole moments throughout 2026.

• Guideline’s 2026 data shows that months like February grew at a significantly higher 11.5% YoY due to the convergence of the Super Bowl and Winter Olympics. June also saw significant growth of 19.3% YoY thanks to the FIFA World Cup.
• September lacked any similar major events that would have encouraged higher ad spending. That impact was felt even by industry giants: Amazon saw its Q3 revenues decelerate notably, partially attributed to a lack of NBA games on Prime in the quarter.