1986: Omnicom formed through merger of advertising agency networks DDB, Needham Harper Steers, and BBDO.
1990: John Wren becomes CEO of Diversified Agency Services, which houses its PR agencies.
1993: Omnicom purchases advertising agency TBWA Worldwide.
1996: Omnicom buys Ketchum; ranks third out of the world's largest holding companies.
1997: Wren named president and CEO of the holding company. Omnicom takes stake in digital and interactive firms Agency.com, Organic Online, Razorfish, and Interactive Solutions.
1998: Omnicom buys advertising network Abbott Mead Vickers, including its UK-based PR agencies Fishburn Hedges, Freud Communications, Aurelia Public Relations, Frew Macmaster, and Hammond Communications.
1999: Omnicom buys Cone for an estimated $12 million to $15 million, adding cause and consumer marketing to its capabilities.
2001: Omnicom's DAS buys healthcare PR and marketing firm Matthews Media Group.
2003: The group purchases a majority stake in Mercury Public Affairs, adding it to the DAS unit.
2007: Word-of-mouth firm Zócalo Group launches; Omnicom buys majority interest in Consultech, a Chinese healthcare market consulting and marketing communications firm.
2009: Omnicom Digital is created to lead all strategic initiatives across the company's digital properties.
2011: Omnicom acquires Marina Maher Communications. Dale Adams is named CEO of DAS, which contains agencies Ketchum, FleishmanHillard, Cone, Porter Novelli, and Marina Maher Communications.
1926: Marcel Bleustein founds Publicis in Paris.
1957: Publicis opens in New York.
1975: Maurice Le´vy becomes CEO of Publicis; Marcel Bleustein-Blanchet (his name after serving in the French resistance in World War II) becomes chairman.
1980: Publicis creates marketing services subsidiaries, including Intelligences, Ide´es, Dialogues Conseil, Media finance, and Mundoprint.
1987: Publicis launches media firm Optimedia in France, the UK, and Switzerland. The company strengthens its advertising and specializes services offerings in Europe.
1999: Burrell Communications, the largest African-American communications firm, is acquired. Publicis is operating in 76 countries and 130 cities around the world.
2000: Publicis acquires Saatchi & Saatchi, which leads to the launch of Publicis Groupe. The holding company is on both the New York and Paris stock exchanges.
2002: Publicis Groupe brings on Leo Burnett, D'Arcy, Manning Selvage & Lee (now MSLGroup), Bartle Bogle Hegarty (49%), and Starcom MediaVest Group. The company triples in size to 35,700 employees in 109 countries.
2006: The holding company acquires Digitas, which has digital and interactive brands such as Digitas, Medical Broadcasting, and Modem Media.
2009: Publicis creates the global PR and events network MS&L Group, which consists of MS&L Worldwide, Publicis Consultants, and Publicis Events. It also acquires digital agency Razorfish.
2011: The holding company buys Rosetta.
2013: Publicis merges Digitas and LBi to form an integrated digital agency network. Digital accounts for more than 35% of Publicis' revenue.