New York—Worldwide online advertising is expected to rise 12.4% this year to $61 billion, according to a new report from MagnaGlobal, the forecasting unit of advertising holding company Interpublic Group of Cos.

In addition, the report noted that paid search has become the most important component of online advertising; Magna expects pay-per-click ads to account for $29.8 billion in expenditures, up 16.5% over the 2009 total. All other online channels combined will grow 8.7% this year, the company said.

Magna also forecast that this growth trend will continue, with an annual 11% growth rate through 2015. Spending is projected to hit $103 billion in 2015, driven by three factors: the rising number of businesses, competitive intensity among advertisers, and the increasing presence of large brands shifting traditional-channel ad spending into digital marketing efforts.