Trust has become something marketers can count in lost revenue. McCann’s Truth About Global Brands study, released on 11 June, found that 69% of people have stopped using a brand they no longer trusted, while 80% say they actively choose the brands they do trust even when those cost more.

That finding lands at a pointed moment. The same research reports that 76% of people fear they will soon be unable to tell whether what they see online is real or generated by AI, and that more than half now name transparency about AI use as the single most effective thing a brand can do to win back trust. Tyler Turnbull, McCann’s global chief executive, called it a “growth crisis” driven by a shift from a trust economy to a doubt economy, and said it is putting CMOs under more pressure than ever.

What McCann’s trust study actually found

McCann’s Truth About Global Brands surveyed 20,713 people across 20 markets between November 2025 and January 2026, the latest wave of a tracking study the agency, part of Omnicom, has run since 2018. Its central claim is commercial rather than reputational: trust now moves purchase decisions in both directions. Some 69% of respondents said they had abandoned a brand once they stopped trusting it, while 80% said they actively choose brands they trust even when those carry a higher price.

The mood underneath the numbers is wary. 72% said prioritising truth matters more than ever, and 55% believed brands were more truthful two decades ago — a slide in confidence the study ties to a more crowded, less legible information environment. The useful translation for a marketing manager is blunt: trust is no longer a soft brand metric reported once a quarter, but a live variable sitting between a campaign and a conversion.

These are self-reported attitudes rather than observed purchases, and the framing serves McCann’s own “Truth Well Told” offer, since the agency sells exactly the brand strategy its research makes the case for. But the direction of travel is consistent across the firm’s earlier waves and a 20-market base, which is more than most vendor surveys can claim.

Why AI sits at the centre of the trust problem

AI is the pressure point the study keeps returning to. McCann found that 76% of people worry they will soon be unable to distinguish real humans from AI-generated ones online, and frames artificial intelligence as a force actively eroding confidence rather than quietly improving service. As synthetic text, images and voices become harder to spot, the cost of a brand being caught looking inauthentic climbs with them.

The actionable finding cuts against a common instinct to keep AI use quiet. Rather than hiding it, people reward brands that disclose it: more than half named transparency about how and where a brand uses AI as the most effective single step to rebuild trust. For teams now wiring generative tools into content, outreach and customer service, that reframes disclosure from a risk to be managed into a growth lever — provided the openness is genuine and not a label bolted onto the same automated output.

The opportunity belongs to marketers who treat AI transparency as a craft decision: saying plainly where a model drafted, personalised or answered a query, and keeping a named human accountable for the claim. The study reads as a warning, but it is also a brief. Doubt is the cost; clarity is the edge.

What the trust shift means for B2B marketers

B2B buyers are not exempt, and the evidence suggests they apply an even harder test. This year’s study drew on independent analysis from Economist Enterprise, the B2B arm of The Economist Group, which examined nearly 1,800 senior B2B decision-makers alongside the consumer sample. Its reading is that business buyers want evidence over affirmation: proof a brand can be experienced consistently and verified independently, not a confident promise taken on faith.

For B2B SaaS teams, where a single mistrusted claim can stall a procurement cycle for months, the practical move is to make proof the default setting. That means specific, checkable outcomes rather than adjectives; independent verification a buyer can follow without taking the brand’s word for it; and clarity about where AI touches the product or the pitch. Marketing leaders speaking around the launch pushed the point further, arguing that trust can no longer be owned by a single department and has to be built across the whole customer experience — the work that turns a stated brand promise into something a buyer actually experiences.

McCann timed the launch to the run-up to Cannes Lions, where trust is expected to dominate the agenda. What the study cannot yet show is whether stated preference becomes spending — whether the people who say they reward openness about AI actually pay the premium they describe. That is the figure marketers, and McCann’s next wave, will be watching for.