eMarketer has revised its online ad spending forecast for 2009, from a previously predicted 4.5 percent increase to $24.5 billion to a 2.9 percent decline to $22.8 billion, Media Post reported.

This revision partly echoed the estimates done earlier this month by the Interactive Advertising Bureau and PricewaterhouseCoopers, which reported a 5.3 percent drop in online ad spending to $10.9 billion in the first half of 2009 year-over-year.

According to eMarketer, moderate growth will recur in the next two years, with spending expected to increase 5.9 percent and 6.6 percent, respectively.

By 2012, online ad spending growth will bounce back to double-digit (12.1 percent), thanks to the presidential election and economic stabilization, Media Post reported.