U.S. Online Ad Market Expected To Double In Four YearsU.S. Online Ad Market Expected To Double In Four Years

The U.S. online advertising market will reach $50.3 billion in revenue by 2011, more than double the amount of last year, a market research firm predicted Friday.

Driving the growth in online advertising over the next few years will be the increasing size of the audience, the development of new types of advertising, and the creation of new publisher business models that will help sell interactive ads, the Yankee Group said.

"With Internet connectivity nearly ubiquitous, online advertising growth is inevitable," Daniel Taylor, an analyst for the firm, said in a statement. Nevertheless, to keep the momentum going, publishers will need to develop new products that take advantage of the evolving digitized environment that goes beyond the PC and into mobile devices.

Yankee predicts that revenue from ads linked to online search will increase, as will animated ads. Social networks will become a part of the online advertising mix, but it's unclear whether they will evolve into the "better mousetrap" of the adverting business. Privacy, however, will remain a concern with users in online advertising.

To take advantage of increasing online ad spending, publishers will need to invest in new technologies that lead advertisers into testing new formats, some of which will ultimately displace the most popular forms today. "You have to spend money to make money, and the proverbial buck will stop with the publishers," Taylor said.

While spending on online advertising is growing, it still accounts for only a small percentage of advertisers' overall budget. Advertisers currently spend 7.5% of their budget online, even though the Internet accounts for 20% of overall media consumption in the U.S., the Yankee Group said.