We study competitive dynamics by using 10 years of data from the biotech industry on patent infringement lawsuits because they capture offensive actions and defensive responses. Results suggest that larger patent portfolios, long-term partnerships, and short-term agreements lead to factor market rivalry. Specifically, long-term research partnerships are associated with lower proclivity and vulnerability to attack, while short-term licensing and marketing agreements with increased proclivity and vulnerability to attack. Lastly, although nonbiotech companies attack biotech firms, the proclivity of the latter to launch cross-industry attacks is not significant. We discuss how the results contribute to competitive dynamics research and theory.