Platforms, Power, and Promotion: Evidence from Spotify Playlists*

Many online markets are dominated by a handful of platforms, raising concerns about the exercise of market power in the digital age. Spotify has emerged as the leading interactive music streaming platform, and we assess its power by measuring the impact of its promotion decisions - via platform-operated playlists - on the success of songs and artists. We employ discontinuity and instrumental variables identification approaches and find large and significant effects of playlist inclusion on success. Our results provide direct evidence of a prominent platform's power and suggest a need for continued scrutiny of how platforms exercise their power.