The merger between Publicis Groupe SA with Omnicom Group Inc. won't simply create the largest advertising firm in the world. The merger would also mean that soda rivals Coca-Cola Co and PepsiCo Inc. would be in the same ad agency.

The merger will have a total of USD23 billion sales and would bring a large stable of global clients. The company will be in a position crafting campaigns that would criticize its own clients. This situation, however, is already common in the advertising world. Nevertheless, the spotlight is on the combined company as potential conflicts of interest that come with a consolidated market. 

Publicis and Omnicom will have full command in the biggest media-buying budget among other ad firms. The new group will purchase ad space in TV, print and Internet with a more favorable price. The scale could give numerous benefits to clients including an assurance that ad campaigns will not be divulged.