It is common for firms to systematically share information with their input suppliers. Although such agreements with horizontal rivals have been analyzed, there has been little work examining vertical sharing, and that analysis has focused on suppliers that set uniform prices. However, there has been a systematic change in the US policy toward vertical relationships in the past decades: both FTC inaction and courts rulings have curtailed the effect of Robinson-Patman, a law meant to prevent differential pricing. Furthermore, it is not clear if differential pricing reflects the suppliers’ or the buyers’ power. The interaction of these effects is examined.