This paper defines conglomerate mergers, setting out the reasons why firms engage in them and lays out the classical theories of harm associated with tying and bundling. It also describes how these theories have been adapted to digital markets, highlighting some of the key efficiencies stemming from conglomerate mergers. It was prepared as a background note for a discussion held at the OECD in June 2020 on the conglomerate effects of mergers.
