Going back to Bain (1956), strategy scholars have long recognized the importance of deterring entry for sustaining incumbents' profits in an industry. We introduce a new mechanism, entry diversion, to better understand the empirical phenomenon of persistent firm entry in spite of investments in entry deterrence by incumbents in some industries. Entry diversion happens when preemptive strategic investments by incumbents decrease the expected future profits from a target submarket such that entrants choose to enter another submarket within the same industry. Empirical evidence from the global semiconductor manufacturing industry suggests that incumbents expand their capacities beyond demand growth, and that these investments effectively divert entry into other submarkets. Greenfield entrants are more responsive to entry diversion than incumbents.