Fair Play: The Deal of the Year Will Be Vertical

The merger wave that started in 2015 and spilled into following years mostly involved blockbuster deals of direct competitors. We saw rapid consolidation in agriculture, pharmaceuticals, and retail.

But that appears to be changing. This year promises to bring tough legal questions about the bounds of antitrust enforcement and what types of arrangements can harm competition as companies in varying industries absorb one another in more creative combinations.

Executive boardrooms and companies are experimenting with unusual pairings, especially in health care. CVS Corp. wants to buy insurer Aetna Inc., and UnitedHealth Group Inc., the biggest U.S. health insurer, will acquire ...