Omnicom Group - Wikipedia

Omnicom Group Inc. is an American global media, marketing and corporate communications holding company, headquartered in New York City. Omnicom's branded networks and specialty firms provide services in four disciplines: advertising, customer relationship management (CRM), public relations and specialty services. The services included in these disciplines are media planning and buying, digital and

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"the world's second largest advertising agency holding companies in terms of revenue and one of the "Big 6" advertising holding companies"