2. European Commission, decisions COMP/M.4439—Ryanair/Aer Lingus, and COMP/M.6663—Ryanair/ Aer Lingus III.
3. See e.g. European Commission, decision IV/M.1036—Chrysler/Distributors (Benelux And Germany), 1998 O.J. (C
4. See e.g. US Department of Justice, 1968 Merger Guidelines, paras 4, 11, 17; European Commission, Guidelines on the
assessment of non-horizontal mergers under the Council Regulation on the control of concentrations between undertak-
ings (‘non-horizontal merger guidelines’), 2008 O.J. (C 265/6), paras 2–4.
5. European Commission, decision M.8124—Microsoft/LinkedIn.
that of the acquiring Tech giant. This type of transaction is traditionally referred to as a conglomerate
acquisition. Whether conglomerate mergers are capable of anticompetitive effects has long been one of
the most contentious areas of substantive merger control. While both the U.S. and EU antitrust authori-
ties had intervened against conglomerate mergers in the earlier days of merger control, conglomerate
effects analysis all but disappeared after the two jurisdictions adopted the consumer welfare aim and
other key teachings of the Chicago School.
This contribution examines whether the advent of the Big Five has changed the European and U.S.
enforcement agencies’ views on conglomerate merger control. To this end, Part II briefly defines key
concepts and terminology. Parts III and IV analyze the evolution of the U.S. and EU antitrust authori-
ties’ approach to conglomerate merger control up until the mid-2000s. Part V explores the enforcement
practice of the past fifteen years — this analysis includes the enforcement practice of the U.K. competi-
tion agency, which is currently developing its own competition policy, having left the European Union
on Jan. 31, 2020. Part VI provides a critical analysis of the key findings and considers whether these
are likely to be lasting changes. Part VII concludes.
II. Typology of Mergers
Conventional wisdom has it that enforcers should differentiate between three types of mergers: hori-
zontal, vertical, and conglomerate. These categories were developed in the age of brick-and-mortar
outlets, when the key commodities traded were either tangible objects or services provided by human
beings. According to this nomenclature, mergers are horizontal if they occur between competitors, that
is, firms that are active in the same product and geographic markets. An example would be an air carrier
acquiring another air carrier operating on the same routes.2
Mergers between companies that are not competitors are commonly described as nonhorizontal.
According to the classic taxonomy, there are two types of nonhorizontal merger: vertical and conglom-
erate. Vertical mergers occur between companies operating at different levels of a product’s supply
chain. They may consist in a manufacturer acquiring a distributor, for example, a car manufacturer
acquiring a car retailer.3 A vertical merger could also entail the manufacturer of an end product acquir-
ing the supplier of a key input, that is, a car manufacturer acquiring a steel company.
Conglomerate mergers, finally, are traditionally defined as mergers between firms that are neither
competitors nor in a vertical relationship, but active in separate, albeit often related, markets.4 An
example of a conglomerate merger would be a tea company acquiring a producer of orange juice.
The preceding examples are fairly clear-cut. However, in the age of digital platforms operating
entire ecosystems of interrelated product and services, the categorization is often less obvious. Take the
example of Microsoft, a global technology company offering, among others, PC operating systems,
servers and mobile devices, related services, cross-device productivity applications, other software
solutions, hardware devices, cloud-based solutions, and online advertising. If Microsoft acquires
LinkedIn,5 which operates a professional social network, with the intention of preinstalling LinkedIn
on its PC operating system Windows, is LinkedIn an input for the Microsoft ecosystem, making the
merger vertical in nature? Or is this a conglomerate merger as Microsoft had not previously offered