A significantbody of empirical research has documented a structural increase in margins across a wide range of industriesand countries.1On average, firms enjoy appreciably greater pricing power today than used to be the casein prior decades.2 Research also showed that this increase in mark-ups coincided with a decline in the labour share of output, higher aggregate concentration, larger corporate profitability, and a slump in business dynamism (as measured by indicators such as entry, investment andinnovation).3 The broader phenomenon of increasedpricing power appears largely (though not unanimously) accepted among researchers. Even so, there is substantial disputeabout its underlying causesand implications.Some researchers have attributed recent margin trendsprimarily to the growth of so-called “superstar firms”—highly profitablecompanies thathave successfully seized the opportunities generated by globalization and technological change (such asdigitization and automation).4Others have linked increasing mark-upsto a lack of competition, e.g., caused by overly permissive merger control.5 Since our earlier workon this topic,6 also antitrust practitioners and agency representatives have started to weigh in on the debate.7 Moreover, both the FTC and the OECD have held public hearings on market power and concentrationto discuss the significance of recent academic findingsfor competition policy.