Identifying Technology Spillovers and Product Market Rivalry
The authors show using panel data on U.S. firms between 1981 and 2001 that both technology and product market spillovers operate, but that net social returns are several times larger than private returns. The spillover effects are also revealed when they analyze three high-tech sectors in detail - pharmaceuticals, computer hardware and telecommunication equipment.
Link
http://cep.lse.ac.uk/textonly/people/bloom/papers/IdentifyingTechnologySpilloversAndProductMarketRivalry.pdf