Financial services advertisers accounted for the most impressions by far--22 percent last month, up slightly from 21 percent in January 2005. Telecoms purchased 19 percent of all online ads, more than double last year's 8 percent. Retail goods and services marketers accounted for 16 percent of impressions, compared to 15 percent last year.

Where did marketers spend their online ad dollars? E-mail sites were a favorite choice, garnering 35.1 percent of impressions--up from both last year's 20.2 percent and last month's 32.1 percent. The bulk of those ads were on Yahoo and MSN; Yahoo Mail drew 22.3 percent of all impressions, while MSN Hotmail garnered 9.6 percent.

General community sites accounted for 13.1 percent of impressions--up from 6.3 percent last year--while portals and search engines claimed 11.8 percent of impressions, down from last year's 16.5 percent share. MySpace once again surged in popularity with marketers, drawing 10.1 percent of all impressions. In December, MySpace accounted for 4.8 percent of ads, which marked a downturn from September's high point so far of 12.4 percent.

Nielsen//NetRatings' AdRelevance doesn't include in the data ads served on proprietary America Online pages, accessed only by AOL subscribers--but counts ads that appear on AOL pages accessed via the Web.

Online Display Impressions March 2005--January 2006