Patent pools, which combine complementary patents of competing firms, are expected to increase overall welfare – but potentially discourage innovation in substitutes for the pool technology. This paper exploits a new historical data set on changes in patenting and firm entry for a clearly...

Patent pools allow a group of firms to combine their patents as if they were a single firm. Theoretical models predict that pools encourage innovation in pool technologies, albeit at the cost of innovation in substitutes. Empirical evidence is scarce because modern pools are too recent to allow...