When Employees Walk Out the Door, Their Memories Remain: The Effect of Inventor Mobility on Patent Renewal

Prior research suggests that patents by mobile inventors are at higher risk of generating spillovers between departed and hiring firms. Despite extensive research on how inter-firm inventor mobility affects firms' learning and innovation, little is known about how firms protect their existing intellectual property in the face of inter-firm inventor mobility. We argue that one main way in which firms try to prevent others from appropriating the value of these inventions is by extending the validity of mobile inventors' patents. We derive a set of hypotheses consistent with this argument and test them using longitudinal data on four major American semiconductor firms. Our analyses show that, as hypothesized, both departed and hiring firms are more likely to extend the validity of mobile inventors' patents than is the case for the patents of other, non-mobile inventors. Furthermore, in line with the view that firms use patent renewal to deter other firms from appropriating mobile inventors' knowledge, we find this effect to be stronger where the risks of spillovers are most intense. Our findings extend prior literature by explicating the role of patent renewal as a strategic deterrent against intellectual property appropriation in the face of inter-firm inventor mobility.