Mega-influencers and brand dynamics: Shaping attitudes toward leading and challenger brands through electronic word of mouth

The aim of this paper is to explore how mega-influencers' electronic word of mouth (eWOM) messages on social media influence consumers' brand attitudes in duopolistic markets. Through three experimental studies, we observe that when mega-influencers send positive (vs. negative) eWOM messages about a leading brand, followers form positive (vs. negative) brand attitudes, but these effects fail to occur when influencers back challenger brands. The findings are consistent across three duopolistic market rivals (Apple vs. Samsung; UPS vs. FedEx; Nike vs. Adidas), three social media platforms (Facebook, Instagram, and X), and four mega-influencers (Marques Brownlee, Gary Vaynerchuk, Kanye West, and Kylie Jenner). Findings indicate that mega-influencers have more persuasive power when recommending or criticizing leading brands rather than challenger brands, irrespective of their follower base. The findings contribute to the marketing literature by showing that in duopolistic market contexts, mega-influencers' e-WOM has varied effects on followers' brand attitudes, depending on brand status in the market.