The U.S. Department of Justice initiated antitrust action in 2010 against several major Silicon Valley technology firms for engaging in anti-poaching agreements. Under the period of labor market collusion, cartel firms displayed elevated job posting rates in roles critical to their innovative activity and depressed inventor departure rates relative to comparable non-cartel firms. Accordingly, cartel firms produced superior innovation output over the collusive period, particularly in technology areas covered by the collusive agreements, while the dissolution of the agreements was accompanied by a reversal of this trend. Event-study tests around the unanticipated antitrust action show a negative returns response. Our results reveal important linkages between reduced employee turnover arising from firms’ anti-competitive conduct in labor markets and their innovation, performance, and market valuations.