David and Goliath: When and Why Micro-Influencers Are More Persuasive Than Mega-Influencers

Social media influencer (SMI) advertising is on the rise; however, extant theory regarding the determinants of SMI advertising effectiveness is undeveloped. The present research establishes when and how the type of SMI based on the number of followers influences SMI advertising effectiveness. Specifically, the findings of four experimental studies show that micro-influencers (those who have 10,000 to 100,000 followers) are more persuasive than mega-influencers (those who have more than 1 million followers) because endorsements by micro-influencers (versus mega-influencers) bestow higher perceptions of authenticity on the endorsed brand, which "rubs off" from the perceptions regarding influencer authenticity. However, this differential effect of SMI type through influencer and brand authenticity occurs only when the endorsed product is perceived as hedonic (as opposed to utilitarian) consumption. From a theoretical perspective, these findings extend prior research on how endorsements from different SMI types vary in terms of their persuasiveness, shed light on the underlying mechanism, and identify consumption type as an important boundary condition. From a practical perspective, we offer managerial implications for enhancing the effectiveness of SMI advertising strategies by taking into consideration SMI types, consumption contexts, and message framing styles.