Goldman Sachs sees 2005 as a "breakout year" for online advertising, and said spending would increase 28 percent, reaching $12.3 billion, MediaPost reports. It also predicts that online advertising could account for as much as seven percent of the ad market by 2009 - up from 4-5 percent last year - with search constituting more than half of all online ad dollars spent. The estimates came in the financial firm's annual internet usage study, based on 2,000 surveys conducted by Synovate.

Earlier this month, Forrester predicted that online advertising would reach $14.7 billion this year, and eMarketer forecast a $12.9 billion market. Last month, The Interactive Advertising Bureau released figures showing online ad spending was up 33 percent in 2004 over the previous year, reaching $9.6 billion.

The Goldman Sachs report also estimates that the proportion of homes with broadband internet access will increase to 59 percent this year, from 50 percent in 2004, and time spent online consuming media will grow to 20 percent, up from 16 percent last year.