More than 75 countries worldwide have enacted merger regimes. Many of these regimes contain a standstill obligation, so that the deal cannot be closed before obtaining antitrust clearance. Antitrust concerns can lead authorities to prohibit a deal, or to require divestments.

Assessing the antitrust risk

Merger control identifies, and prohibits or appropriately limits, transactions that threaten to create or enhance a dominant market position or otherwise lessen or impede competition. The precise standard varies from jurisdiction to jurisdiction. Antitrust authorities are mainly concerned with horizontal antitrust issues, that is, the parties sell competing products and the transaction leads to high combined market shares; vertical restraints, in particular the potential foreclosure of a supplier or customer; or conglomerate antitrust concerns, where (absent horizontal or vertical overlaps) the combined product portfolio of the parties leads to market power.

Authorities generally review mergers in a two-step process. A first, shorter and more administrative,...