This paper studies the impact of cash constraints on equilibrium winning probabilities in a patent race between an incumbent and an entrant. We develop a model
where cash-constrained firms finance their R&D expenditures with an investor who cannot verify their effort. In equilibrium, the incumbent faces better prospects of
winning the race the less cash-constrained he is and the more cash-constrained the
entrant is. We use NBER evidence from pharmaceutical patents awarded between
1975 and 1999 in the US, patent citations, and COMPUSTAT to measure the
effect of the incumbent's and entrants' cash holdings on the equilibrium winning
probabilities. The empirical findings support our theoretical predictions