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Frontiers: How Much Influencer Marketing Is Undisclosed? Evidence from Twitter

Daniel Ershov, Yanting He, Stephan Seiler. 2025. Marketing Science, 44(3), 505-515.

Abstract

We study the disclosure of influencer posts on Twitter across a large set of brands using more than 100 million posts and a text-based classifier for undisclosed sponsorship. In the preferred empirical specification, 96% of sponsored posts are not disclosed; a lower-bound classification still implies an undisclosed share of 82%. Despite stronger enforcement of disclosure regulations, the share of undisclosed posts decreases only slightly over time. Compared to disclosed posts, undisclosed posts tend to be associated with young brands with a large Twitter following.

Main Finding

Most sponsored influencer advertising in the Twitter data is undisclosed: 96% in the preferred specification and 82% under a lower-bound classification.

Policy Relevance

Disclosure enforcement can miss most sponsored content consumers encounter, so researchers and regulators need tools that detect non-disclosed advertising directly.