Platform Openness: Evidence from Bug Bounty Programs

We examine how complementor-level openness affects value capture in platform markets. We argue that openness changes not only the amount of activity a complementor receives, but also its composition and the value the complementor can extract from it. Using bug-bounty program data, we find that closed programs attract cleaner activity and higher-quality researchers, but overall activity declines over time. Transitioning to an open structure can revitalize activity, but it also increases duplicates and reduces average contributor quality. Monitoring effort, which helps determine how much of the activity is converted into realized-value, is more productive under selective access. We contribute to platform governance research by showing that openness is a dynamic complementor-level governance lever whose value depends on activity volume, flow composition, and monitoring density.