The number of cost-per-thousand impression display ads reached 254.2 billion in October, up from 232.1 billion in September, with financial services advertisers accounting for 30 percent.

Financial services' 30 percent share was up from 21 percent a year earlier and 28 percent from Sept., as tracked by Nielsen/NetRatings AdRelevance, MediaPostreports. Web media was the second-largest online advertiser category with 17 percent of impressions, followed by retail goods and services (16 percent) and telecom (10 percent).

Email sites again accounted for the largest proportion of impressions - 51.1 percent - with Yahoo Mail accounting for 43.6 percent of ads and MSN Hotmail 6.3 percent. MySpace alone accounted for 15.9 percent. Portals and search engines accounted for 7.7 percent of impressions.