Pepsi-Versus-Coke Ad War Has Publicis-Omnicom Win Either Way

Publicis Groupe SA’s merger with Omnicom Group Inc. won’t just create the world’s largest advertising company: it will mean longtime rivals such as Coca-Cola Co. and PepsiCo Inc. are sharing the same firm.

The business will have $23 billion in sales and bring together a large stable of global clients, putting it in the position of crafting campaigns that criticize its own customers. While that situation is already increasingly common in the ad world, the deal is putting a spotlight on the potential conflicts of interest that come with a consolidated market.