Do financial markets price knowledge spillovers? We show that patent grants influence the stock returns of firms that are connected through technological knowledge dependencies.

Using directed patent citations among publicly listed companies in the United States, we construct a granular measure of each firm's exposure to new patents granted to its technologically upstream firms. Patents granted to these upstream companies significantly boost its abnormal stock returns during the week of the grant. This contrasts with the gradual fade-out of returns from a firm's own patent grants, indicating a gradual diffusion of information in markets. We find that these financial spillovers are predominantly localized within a firm's immediate technological connections. Additionally, we provide a novel empirical decomposition of financial spillovers generated from patent grants, by distinguishing those spillovers emerging from sources of technological knowledge, from those emerging from product market rivals (negative effect) and suppliers (positive effect). Our findings are robust to alternative specifications and placebo tests, and they suggest that technological knowledge spillovers create important market-priced ties between firms that are not fully captured by traditional product market relationships.