ChatGPT Agrees With Other AI Engines Less Than 60% of the Time on Brand Recommendations
ChatGPT's brand mention overlap with Gemini is 58%, the lowest pairwise agreement between any two AI engines across three waves of data. ChatGPT has the lowest overlap with 3 of the other 4 engines, dropped an established brand (ActiveCampaign) from its responses entirely in one week, and gave Netlify its first-ever #1 recommendation after 28 consecutive appearances without one.
The engine that carries the most traffic is also the one that behaves least like the others. For brands tracking AI search visibility, that combination creates a specific problem: you cannot predict what ChatGPT will do by watching the other four engines.
Context: Three Waves, 300 Engine-Query Pairs
These findings come from FogTrail's three-wave citation study, which tracked 25 B2B SaaS brands across 20 queries and 5 AI search engines (ChatGPT, Perplexity, Gemini, Grok, and Claude). Each wave produced 100 engine-query pairs. Across three weekly waves, that is 300 data points, enough to separate durable patterns from one-off noise.
As of March 2026, the data shows that AI engine recommendations are not converging toward agreement. They are oscillating. And ChatGPT is oscillating the most.
The Data: ChatGPT Is Diverging From the Pack
Here is the pairwise brand mention overlap for Wave 3. Each cell shows the percentage of brands that both engines mention for the same queries.
| Perplexity | ChatGPT | Gemini | Grok | Claude | |
|---|---|---|---|---|---|
| Perplexity | - | 64% | 67% | 67% | 62% |
| ChatGPT | 64% | - | 58% | 71% | 62% |
| Gemini | 67% | 58% | - | 74% | 69% |
| Grok | 67% | 71% | 74% | - | 75% |
| Claude | 62% | 62% | 69% | 75% | - |
ChatGPT-Gemini at 58% is the lowest pair in the entire three-wave dataset. Meanwhile, Grok-Claude hit 75%, the highest. The other four engines are forming a loose cluster. ChatGPT is drifting away from it.
How ChatGPT's Overlap Has Changed Over Three Waves
| ChatGPT Overlap With | Wave 1 | Wave 2 | Wave 3 | Direction |
|---|---|---|---|---|
| Gemini | 62% | 67% | 58% | Diverging |
| Claude | 61% | 67% | 62% | Diverging |
| Perplexity | 64% | 65% | 64% | Flat |
| Grok | 58% | 70% | 71% | Converging |
ChatGPT is selectively aligning with Grok while pulling away from the Perplexity-Gemini-Claude cluster. The ChatGPT-Gemini relationship shows the clearest decline: a 9-point drop from Wave 2 to Wave 3.
Supporting Evidence: Three Moves Only ChatGPT Made
The overlap numbers tell a structural story. But the individual brand movements make it tangible.
ActiveCampaign: Cited to Invisible in One Week
ActiveCampaign appeared on all 5 engines in Waves 1 and 2. ChatGPT cited it twice in Wave 2 with direct URL links. In Wave 3, ActiveCampaign vanished from every ChatGPT email marketing response. Zero mentions across all 4 email queries.
| Engine | ActiveCampaign Mentions (W3) | Wave 2 | Wave 1 |
|---|---|---|---|
| Gemini | 4 | 4 | 4 |
| Claude | 3 | 3 | 3 |
| Perplexity | 2 | 3 | 3 |
| Grok | 2 | 4 | 4 |
| ChatGPT | 0 | 2 | 2 |
The other four engines continued mentioning ActiveCampaign normally. This was not a universal signal change, it was ChatGPT-specific behavior. A midmarket brand went from cited with links to completely invisible on the highest-traffic AI engine in a single week.
Netlify: A First-Ever #1 That Only ChatGPT Gave
Netlify had appeared in 28 engine-query pairs across two waves without a single #1 placement. In Wave 3, ChatGPT recommended Netlify ahead of Vercel for "best platform for deploying web apps." No other engine made this change.
| Metric | Wave 1 | Wave 2 | Wave 3 |
|---|---|---|---|
| Netlify at #1 | 0/14 (0%) | 0/14 (0%) | 1/16 (6%) |
| Vercel at #1 | 14/14 (100%) | 15/16 (94%) | 14/16 (88%) |
Vercel still dominates at 88% position-1 rate. But the strongest structural pattern in the dataset, Vercel's lock on the top spot, was broken by ChatGPT and only ChatGPT.
Startup-at-#1 Rate: A 40% Drop
ChatGPT held a 25% startup-at-#1 rate across Waves 1 and 2, the highest of any engine. In Wave 3, it dropped to 15%.
| Engine | Startup at #1 (W1) | W2 | W3 |
|---|---|---|---|
| ChatGPT | 25% | 25% | 15% |
| Claude | 10% | 15% | 5% |
| Gemini | 5% | 10% | 10% |
| Grok | 5% | 10% | 10% |
| Perplexity | 0% | 5% | 5% |
ChatGPT lost PostHog at #1 for analytics queries and Fly.io at #1 for hosting. No engine now exceeds 15% startup-at-#1 rate. The "ChatGPT is most startup-friendly" narrative from earlier waves no longer holds.
What Makes ChatGPT Structurally Different
ChatGPT's divergence is not random noise. It has consistent behavioral quirks that the other engines do not share.
Wikipedia reliance. ChatGPT sourced 10.4% of its citation URLs from Wikipedia in Wave 3. No other engine uses Wikipedia at all. This unique source dependency means ChatGPT's knowledge graph draws from a fundamentally different information base.
Citation count volatility. ChatGPT's brand citation count swung from 23 (Wave 1) to 12 (Wave 2) to 14 (Wave 3). Compare that to Claude's perfectly stable 6, 6, 6 across the same period. ChatGPT is the least deterministic engine in the dataset.
Brand-owned URL preference. Despite declining from 24.2% to 18.4%, ChatGPT still links to brand-owned websites at roughly 4x the rate of Perplexity, Gemini, or Claude. It rewards product pages and documentation more heavily than any other engine, a behavior that matters for how brands get cited by ChatGPT.
What This Means
The engine that matters most is the hardest to predict. ChatGPT commands the largest share of AI search traffic. It is also the engine whose recommendations you are least likely to guess by monitoring Perplexity, Gemini, or Claude. This is the central problem for any brand doing AEO as of March 2026: the most important engine is the outlier.
Single-engine optimization is riskier than it looks. If you optimize for ChatGPT specifically, you are targeting an engine that changes its brand recommendations more aggressively than any other. ActiveCampaign learned this the hard way. A brand can be cited and linked one week and completely absent the next.
Multi-engine monitoring is not optional. The pairwise overlap data has been consistent across three waves: no two engines agree on more than 75% of brand mentions. ChatGPT's divergence makes this problem worse, not better. You cannot extrapolate ChatGPT's behavior from the other four engines.
ChatGPT's volatility creates openings. Netlify's first-ever #1 happened on ChatGPT. Beehiiv's newsletter breakthrough started on ChatGPT. The same instability that makes ChatGPT dangerous for incumbents makes it the most accessible engine for challengers. If you are trying to break into a category, ChatGPT is where the door is most likely to open.
What You Can Do About It
- Track ChatGPT separately from your multi-engine dashboard. Its behavior diverges enough from the other four engines that aggregated metrics will mask ChatGPT-specific changes.
- Monitor your brand's ChatGPT presence weekly. ActiveCampaign's disappearance happened between weekly checks. Monthly monitoring would have missed it entirely. A 48-hour monitoring cadence catches these shifts before they compound.
- Invest in brand-owned content for ChatGPT specifically. ChatGPT sources from brand websites at 4x the rate of other engines. Pricing pages, feature comparisons, and technical documentation directly influence ChatGPT citations more than any other engine.
- Do not assume ChatGPT position changes are permanent. Netlify's #1 may revert. ChatGPT's startup-at-#1 rate may rebound. The engine's volatility works both ways.
- Watch the ChatGPT-Grok convergence. These two engines are increasingly aligning (58% to 71% overlap over three waves). Strategies that work for ChatGPT may start paying off on Grok as well.
Methodology
We ran 20 queries across 5 AI search engines: ChatGPT, Perplexity, Gemini, Grok, and Claude. Each query was sent as a real-time API call, simulating how actual users interact with these platforms. We tracked 25 B2B SaaS brands across 5 categories (CRM, Project Management, Email Marketing, Analytics, Dev Tools) over three weekly waves (March 6, 10, and 15, 2026), recording brand mentions, citation URLs, and position rankings. Pairwise overlap is calculated as the Jaccard index of brand mentions shared between two engines across all 20 queries.
Frequently Asked Questions
How much does ChatGPT agree with other AI search engines on brand recommendations?
As of March 2026, ChatGPT's brand mention overlap ranges from 58% (with Gemini) to 71% (with Grok). It has the lowest pairwise agreement with 3 of the other 4 engines, making it the most divergent AI search engine in a five-engine comparison.
Can a brand disappear from ChatGPT in a single week?
Yes. ActiveCampaign went from being cited with direct URL links on ChatGPT to zero mentions across all email marketing queries in one week. The other four engines continued mentioning it normally. Single-engine disappearances can happen without any change on other platforms.
Is ChatGPT still the most startup-friendly AI engine?
No. ChatGPT's startup-at-#1 rate dropped from 25% in Waves 1 and 2 to 15% in Wave 3. No engine now recommends startup brands first more than 15% of the time. The enterprise advantage in AI search recommendations remains resilient.
Why does ChatGPT behave differently from other AI engines?
ChatGPT has several unique behaviors: it sources 10.4% of its URLs from Wikipedia (no other engine does this), it links to brand-owned websites at roughly 4x the rate of Perplexity or Claude, and its citation counts swing dramatically between weeks. These structural differences in sourcing produce different brand recommendations.
Should brands optimize for ChatGPT specifically?
Brands should monitor ChatGPT specifically because its behavior cannot be predicted from other engines. However, optimization should not be ChatGPT-exclusive. The engine's volatility means that any position gained can shift quickly. A multi-engine strategy with extra attention to ChatGPT is the most practical approach.
Related Resources
- We Asked 5 AI Engines the Same 20 Questions. They Disagreed on the #1 Answer 50% of the Time.
- AI Search Engines Are Forming Alliances: Which Engines Agree and Why It Matters
- How to Get Your Startup Cited by ChatGPT
- What Happens When an AI Engine Drops Your Brand Overnight
- How Often Do AI Search Engines Update Citations?