BBDO Worldwide, New York
A brilliant copywriter, Rosenshine began his BBDO career in 1965 and by 1986 rose to chairman of what was called BBDO International. Recognizing the importance of meeting the Saatchi brothers' global agency network challenge in the mid-'80s, Rosenshine conducted intensive, secrecy-cloaked merger talks that culminated in April 1986 with the so-called "Big Bang," a merger that created the Omnicom Group, the world's largest three-network conglomerate consisting of BBDO (No. 6) and a merged Needham Harper Worldwide (No. 16) and Doyle Dane Bernbach (No. 12), plus a Diversified Agency Services unit to hold smaller operations. Despite client defections, differing agency cultures and much skepticism, CEO Rosenshine led it to financial success.