Omnicom Group, a leading global marketing and corporate communications company, has been involved in several significant mergers and partnerships over the years. Here are some notable examples:

1. Acquisition of TBWA: In 1986, Omnicom acquired TBWA, a prominent advertising agency known for its creative campaigns. This acquisition helped Omnicom expand its global reach and enhance its creative capabilities.

2. Merger with DDB Needham: In 1986, Omnicom was formed through the merger of DDB Needham and BBDO, creating one of the largest advertising networks in the world. This merger solidified Omnicom's position in the advertising industry.

3. Partnership with Publicis Groupe: In 2018, Omnicom and Publicis Groupe announced a strategic partnership to collaborate on marketing solutions and technology services. This partnership aimed to leverage their combined strengths to better serve clients.

4. Acquisition of Digital Agencies: In recent years, Omnicom has expanded its capabilities in digital marketing through various acquisitions, including agencies like Critical Mass and Flock Associates. These acquisitions are part of Omnicom's strategy to enhance its digital offerings and adapt to the changing marketing landscape.

5. Investment in Programmatic Advertising: Omnicom has also partnered with technology firms to strengthen its programmatic advertising capabilities, providing clients with more efficient and targeted advertising solutions.

These mergers and partnerships reflect Omnicom's ongoing strategy to innovate and adapt in the rapidly evolving marketing and communications landscape. For more detailed information, you can check sources like Omnicom Group's official website or industry news articles.