Methods, systems, and apparatus include computer programs encoded on a computer-readable storage medium, including a system that controls content distribution using a feedback loop. Content is distributed over multiple different online channels using a same initial maximum selection value for distribution over each different online channel. An observed distribution amount required for distribution of the content over the multiple different online channels is received through a feedback loop and for multiple different distributions of the content. Based on the observed distribution amount received through the feedback loop, a realized distribution amount is determined for the multiple different distributions across the multiple different online channels. The maximum selection value is adjusted based on a difference between the realized distribution amount and a reference distribution amount specified by a provider of the content. The content is distributed over the multiple different online channels using the adjusted maximum selection value.