EXPRESS: Are Exposure Bucks Worth It? Evidence from Instagram

Using Instagram's recently introduced collaborative post feature, which lets brands credit creators in shared posts seen by the brand's followers, this study quantifies the value of exposure to a brand's audience for small-to-mid-tier sized creators. We assemble a novel dataset linking all collaborative posts from 260 leading fashion and beauty brands to a daily panel of follower counts for the participating creators. To identify causal effects, we exploit rigidity in brands' posting schedules together with high-frequency daily data, attributing the discrete jump in follower growth on the exact post date to brand exposure. To address post content endogeneity, we match treated and control posts on visual content using GPT-4o embeddings and additional aesthetic features. On average, a collaborative post increases a creator's follower count by 0.52%--roughly one week of organic growth--and yields a conversion rate from brand followers to creator followers comparable to online display advertising. We find no effect on engagement or on creators' subsequent sponsored work with other brands. Although larger brands offer greater reach, their followers are less engaged and their collaborative content deviates further from creators' typical style, resulting in roughly constant treatment effects across brands ranging from 0.7 to 8.6 million followers.