• by Wendy Davis  @wendyndavis, July 18, 2006

Social networking site MySpace last month garnered 17 percent of online display impressions--up more than two points from May's 14.6 percent, according to new data by Nielsen//NetRatings AdRelevance.

The most popular site with advertisers remained Yahoo Mail, which drew 35.7 percent of impressions. MSN Hotmail came in a distant third, behind MySpace, with 7.2 percent of ads.

Financial services companies accounted for the single largest proportion of online ads--24 percent, according to Nielsen//NetRatings. That share however, marks a drop from May's 28 percent.

Telecoms and Web media each accounted for 18 percent of the online ads tracked by Nielsen//NetRatings, compared to 17 percent and 13 percent, respectively, in May. Retail goods and services claimed 16 percent of online ads, the same as in May.

The overall number of display ad impressions tracked by Nielsen//NetRatings AdRelevance dipped to 193.6 billion last month, down from 197.7 billion in May and 197 billion in April, but almost double 97.1 billion in June.

But Nielsen//NetRatings has cautioned that year-over-year surges in a number of online impressions it measures doesn't necessarily reflect a corresponding growth in online advertising. Rather, the company has said that changes in its methodology might account for the apparent ballooning numbers. For instance, Nielsen//NetRatings AdRelevance now examines more sites than it did last year.

The AdRelevance data doesn't include ads served on proprietary AOL pages, but counts ads that appear on AOL pages accessed via the Web.