ChatGPT's advertising business is showing early signs of stronger engagement. An analysis from Graphite using Similarweb data found that the click-through rate for ChatGPT ads more than doubled from late March to early September 2026.
The same research shows that the emerging inventory currently has a strong B2B tilt: business software accounted for almost 20% of observed ad impressions between March and August, followed by business and professional services at 8.5% and developer tools at 4.6%.
CTR more than doubled in roughly five months
The increase in click-through rate is one of the clearest early performance signals for ChatGPT advertising. Graphite CEO Ethan Smith told Business Insider that the improvement suggests targeting is getting better as the platform develops.
However, these figures come from independent market measurement rather than OpenAI's own advertising performance reporting. Similarweb's AI advertising products observe real-user activity across personalized AI conversations, providing an external view into a channel that remains difficult to measure from outside.
B2B software dominates the early inventory
Business software generated nearly one in five observed impressions in the analyzed period. Professional services represented another 8.5%, while developer tools accounted for 4.6%.
The advertiser mix fits ChatGPT's early commercial audience. Software and AI-focused companies are targeting users already working inside an AI assistant, creating a natural overlap between conversational AI usage and demand for productivity, marketing and developer products.
Most eligible reach is still untapped
Perhaps the most important growth signal is reach. Business Insider reports that fewer than half of ad-eligible users had been served an advertisement at all. Separate reporting on the Graphite and Similarweb research puts U.S. ad-eligible reach at 43%.
That leaves substantial room for additional inventory even before considering new markets, formats or broader eligibility.
ChatGPT advertising is still an experimental channel
The improving CTR should not be read as a mature industry benchmark. Recent Graphite and Similarweb reporting shows substantial differences between countries: reported CTRs through mid-September ranged from around 0.6%–0.75% in several English-speaking markets to above 1% in Brazil, Mexico, Japan and South Korea.
The advertiser base, creative strategies and delivery mechanics are also still changing quickly, making historical comparisons particularly sensitive to market mix and rollout changes.
The NetContentSEO view
For AI visibility, ChatGPT ads introduce a second competitive layer alongside organic citations and mentions. Brands are no longer competing only to become part of an AI-generated answer; they can increasingly compete for a commercial placement attached to the same conversational intent.
The combination of rising CTR, limited current reach and a B2B-heavy advertiser mix suggests an advertising market that is gaining traction but remains early. As inventory expands, the key question will be whether conversational context allows ad relevance to improve beyond what traditional keyword-driven search advertising can achieve.