• by Laurie Sullivan  @lauriesullivan, July 19, 2012

GroupM released Thursday a revised forecast for growth in ad spending. The company now estimates 5.1% growth to $506.3 billion for global media spend in 2012, down from 6.3% projected late last year. The 70-country forecast also predicted global ad spending in 2013 will rise 5.3% to $533.2 billion.