Williams will join PHD New York in April and will report to Monica Karo, who has been promoted from president of integrated global accounts at Omnicom Media Group to the position of chief executive of PHD US.
In the UK Williams will not be directly replaced. Incoming managing director at OMD UK Dan Clays, and Robert Ffitch, managing director at Manning Gottlieb OMD, will report directly to Philippa Brown, chief executive of OMG UK.
Williams began his career at Bates and spent time at Leagas Delaney, Yellowhammer, Initiative Sydney and BBDO. After joining the media department of BMP, he moved to OMD when it broke out as a separate agency in 1996.
Williams was promoted through the agency first to head of TV trading, then to managing director of OMD UK, and then group chief executive.
Mike Cooper, chief executive of PHD Worldwide, said: "Omnicom Media Group has an unfair share of the best talent in this business and these appointments reinforce our commitment to providing best-in-class leadership for PHD USA.
"We are hugely excited to be welcoming Monica and Steve to the PHD family and are confident that they will build on the great success we’ve enjoyed over the last two years."
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