Dispute the patent, short the stock: Empirical analysis of a new hedge fund strategy

Findings were that the mere filing of a patent opposition in fact produces statistically significant negative returns. The result is robust with the abnormal return being −30 base points. In addition, multiple linear regression results confirm the conjecture that the higher the importance of the disputed patent, the higher the negative abnormal return on the filing date will be. However, transaction cost simulations prove that this strategy is still highly speculative and cannot be considered a real threat to patent holders or the US intellectual property system. The only ones who should start worrying are the few patent owners who really rely on absolutely unjustified and tenuous patent protection.