Shill Advertising

Shill advertising occurs when sellers confidentially pay influencers to transmit favorable messages about a product. Here, we present a two-period model involving informed sellers, influencers, and second-period followers. Our model addresses why sellers of low-quality products engage more in shill advertising, despite the longstanding argument that high-quality sellers advertise more to encourage repeat purchases. We show that high-quality sellers have less incentive to engage in shill advertising, as doing so undermines the credibility of word-of-mouth communication from first-period influencers. This new insight into advertising behavior is primarily driven by what we call the “credibility effect”.