Complementarity, Fragmentation, and the Effects of Patent Thickets

This paper empirically investigates the effects of patent thickets. One unique feature of our study is to identify two sources of patent thickets: (1) complementarity as measured by the number of the patents to be used jointly with the focal patent in commercialization, and (2) ownership fragmentation as measured by the number of firms whose patents are cited by an examiner for the granting of the focal patent.There are three major findings. First, there is a significant difference between complex industry sectors and discrete ones regarding complementarity, while the difference regarding fragmentation at the patent level is small. Second, more complementarity is significantly associated with the importance of first mover advantage in research and development (R&D) and (less significantly) with that in commercialization, while fragmentation has little effect on them. Consistent with this finding, complementarity is associated with high patent value. Third, cross licensing motivation significantly accounts for patenting propensity while blocking motivation does not. Complementarity is significantly associated with more patenting for cross licensing, which facilitates both combining the inventions of different firms and preventing the risk of being held up. Furthermore, it does not invite patenting for blocking.Thus, we do not see significantly negative consequences of patent thickets on R&D, as seen by incumbents. At the same time, it is important to pay focus on policy to avoid granting patents to low quality inventions and to facilitate the mechanism of ex-ante contracting in complex industry sectors where patenting motivations are high.