The ad-supported internet ecosystem accounts for 3.7% of American GDP

"Employment in the ad-supported internet ecosystem doubled over the past four years to 5.1 million, making it one of the most dynamic sectors in the recessionary American economy, according to a study by researchers at the Harvard University Business School, commissioned by the Interactive Advertising Bureau (IAB). The ecosystem contributed $530 billion to the U.S. economy last year, close to double 2007 figures, and accounted for 3.7 percent of the U.S. gross domestic product (GDP), an uptick from 2.1 percent four years ago.
These key findings are from the 2012 “Economic Value of the Advertising-Supported Internet Ecosystem,” a comprehensive update to a study by the same name released by IAB in 2009, reviewing data from 2007. John Deighton, Harold M. Brierley Professor of Business Administration, Harvard Business School, who helped lead the previous version, directed the current study, with Leora D. Kornfeld, Research Associate, Harvard Business School, serving as principal investigator. The research was unveiled today at the annual IAB MIXX Conference in New York City to quantify the significant role the ad-supported digital sector plays in the expansion of the broader U.S. business landscape."
Source:  Press release from the IAB, 1st October 2012