Online ads will account for 4.6% of all US advertising in 2005, up from an estimated 3.7% in 2004, according to Merrill Lynch. Previously, the company predicted that online ad dollars would represent 4.2% of all US advertising in 2005. By 2009, online advertising will climb to 7.4% of the total US advertising spend, up from a previous estimate of 5.3%. Paid search will represent 39.8% of total online ad dollars this year and 43.8% by 2009. Both estimates are downward revisions from the company’s previous forecast that paid search would come to 43% of this year’s online ad spend and 55.5% of that of 2009.