• by Wendy Davis  @wendyndavis, December 15, 2006

Online marketers ran 259.6 billion display ads last month--up from 254.2 billion in October, according to new data by Nielsen//NetRatings AdRelevance.

Financial services advertisers accounted for more ads than marketers in any other category--25% last month--but that proportion was down from 30% in October and 28% in September.

Web media accounted for the second-largest category, with 20% of impressions--up from 17% in October. Retail goods and services accounted for 16% of impressions--the same as in October--while telecoms accounted for 10%, also flat from October. Rounding out the top five categories was public services, with 9% of impressions--up slightly from October's 8%.

E-mail sites accounted for 47.5% of last month's impressions, with Yahoo's e-mail service drawing 40.4% of ads and MSN Hotmail accounting for 5.7%. All of those numbers were down slightly from October, when e-mail accounted for the majority of impressions--51.1%--with Yahoo's e-mail service garnering 43.6% of ads, and MSN Hotmail claiming 6.3%.

Last month, general community sites drew 15.3% of impressions, with MySpace alone claiming 14.3%. Those figures also marked a drop from October, when general community sites drew 16.8% of impressions and MySpace accounted for 15.9%.

In addition, portals and search engines garnered 7.4% of impressions, down slightly from October's 7.7%. General/national news sites accounted for 4.4%--up from 3.9%--and entertainment sites drew 3.4%, up from October's 2.7%.

Nielsen//NetRatings AdRelevance doesn't track certain types of online advertising, including pre-roll, partnerships, and sponsorships. The AdRelevance data also doesn't include ads served on proprietary AOL pages, but counts ads that appear on AOL pages accessed via the Web.