Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
This article investigates the relationship between the Herfindahl–Hirschman Index (HHI) and welfare in multiple‐leader Stackelberg models. We formulate two long‐run models of free entry of followers; in the first (second) model, leaders select their output before (after) the entry of the followers. We find that in both models, in contrast to the short‐run models, the Stackelberg model yields a larger welfare and HHI than the Cournot model does regardless of the number of leaders; that is, beneficial concentration always occurs.