Social media influencer over-endorsement: Implications from a moderated-mediation analysis

The surge in social media's popularity has catalyzed the emergence and growth of social media influencers (SMIs) and their pivotal role in marketing strategy. This study examines the impact of SMI over-endorsement on consumer purchase intentions, mediating this relationship through influencer authenticity and credibility, and moderating it with product interest. Employing a moderated-mediation model using partial least squares structural equation modeling (PLS-SEM), this study analyzes survey data collected from 303 social media users. Contrary to intuitive expectations, SMI over-endorsement does not directly affect consumer purchase intentions; instead, its negative influence is significantly mediated by reduced perceptions of credibility among SMIs, with product interest serving as a mitigating mechanism. This revelation challenges conventional beliefs by revealing that the negative repercussions of excessive endorsements are mediated by credibility erosion, overshadowing any concerns regarding authenticity. Importantly, this adverse effect can be mitigated by fostering product interest as a strategic buffer. This suggests that rather than curtailing endorsement frequencies, brands and SMIs should focus on amplifying product interest (e.g., by enhancing product engagement and relevance) and thus sustain or even increase endorsement activities without compromising the perceived credibility of influencers, thereby maintaining the effectiveness of influencer marketing campaigns. This study therefore contributes novel insights into the dynamics of influencer marketing, particularly the adverse effects of over-endorsement on consumer behavior and the conditions under which these effects may be neutralized.