IAB’s September update is useful because it does not simply say the ad market is bigger. It says the planning environment has changed. On September 10, 2026, IAB raised its full-year U.S. ad spend growth forecast to 12.3%, up from 9.5% in January, after a stronger first half and major live-event demand.
For a CMO, that is not a permission slip to spend more everywhere. It is a trigger to reopen the forecast: which channels are getting more competitive, which business goals deserve incremental money, and which measurement gaps make extra spend risky?
What changed in the forecast
IAB said more than 200 brand and agency decision-makers informed the update. The trade group pointed to the Winter Olympics, the FIFA World Cup, easing macro concern among buyers and changing consumer behavior. It also reported that customer acquisition rose as a priority to 63%, while brand equity moved up to 43%.
The channel detail matters. Social media, CTV and commerce media showed the strongest projected growth among major channels, while paid search growth was more modest. That mix tells marketers where auctions, inventory access and creative quality may become more contested.
Why this is a planning problem
When the market grows faster than expected, the first bad habit is to average the news into the whole plan. A brand adds a little to every channel, calls it confidence, and learns very little. The second bad habit is to chase the highest-growth channel without asking whether the company has enough creative, retail data, audience proof or sales capacity to use that channel well.
The better response is a reforecasting meeting with finance, media, ecommerce, sales and analytics. The question is not “Can we increase spend?” The question is “Where does one more unit of budget create the clearest business option?”
A four-part reforecast model
Separate market growth from company readiness. If commerce media is growing but your product feed, retail partner data and incrementality design are weak, the market signal does not automatically justify more budget.
Protect acquisition economics. IAB’s data shows renewed interest in customer acquisition. That makes sense when consumers are switching brands and store brands more readily. But acquisition budgets need marginal CAC, first-order margin and repeat-rate checkpoints, not only platform ROAS.
Fund brand equity with proof of memory. Brand budgets should not hide from measurement. Track branded search, direct traffic, share of search, creator lift, retail search behavior and survey signals where available. The goal is to measure whether the brand becomes easier to choose.
Add AI discovery as an evidence line. IAB also noted buyer focus on AI-driven discovery and AI visibility. Do not create a separate hype budget. Add prompts, citations, referral quality and answer visibility to the same measurement conversation.
Where to move first
Incremental money should go where there is both market opportunity and operational confidence. A retailer with strong product data may test commerce media. A B2B brand with expensive consideration cycles may test creator or publisher environments with first-party data. A consumer brand with proven video assets may add CTV or social only if frequency and creative fatigue are controlled.
Hold back a reserve. Forecasts can be right about the market and still wrong for a particular category. A reserve lets the team respond to auction inflation, competitor activity, inventory changes or creative learnings without rewriting the whole plan again.
The decision for leaders
Treat the IAB update as a reason to make choices explicit. Which goal gets the next budget tranche: new customers, brand equity, retail conversion, AI visibility or retention? Which metric will prove the move worked? Which team owns the next decision date?
The companies that benefit from a stronger ad market will not be the ones that simply spend into it. They will be the ones that reforecast faster, keep evidence at the center, and know when optimism has turned into unmeasured noise.
