The article addresses the dynamics through which product markets become derailed from early product life cycle (PLC)-tracks and engaged in complementary convergence with other product markets or industries. We compare and contrast the theories that can explain, respectively, the PLC and the derailing of this cycle into a process of complementary convergence. The article challenges the standard industry conception and proposes a distinction between the emergent industrial sector, the emergent product market (or niche) and the industry as a more well-established entity. Based on empirical evidence from the IT security sector, two trajectories of complementary convergence are identified, “lower-order integration”, the integration of different product markets in a sectoral context, and “higher-end integration”, the integration of product markets into the offerings of established industries. While young ventures dominate lower-order integration, incumbents in established industries dominate higher-order integration. For both trajectories mergers and acquisitions represent a central means for realizing convergence.