Net Firms Save Ad Space for Self-Promotion

Despite strong growth in the number of companies paying to advertise on the Internet, a significant number of firms fill their Web site ad space with banner ads promoting their own products and services, according to a report released today.

AdRelevance, a division of Media Metrix Inc., said that house advertising--ads placed by Web publishers on their own sites--accounts for about 20% of all available online ad inventory. The Internet advertising measurement firm said it monitored house advertising on the 500 highest-trafficked ad-supported sites between January and April.

The study found 179 online companies devoted more than 1% of their inventory to house advertising, accounting for more than 17 billion online ad impressions out of a total of 92 billion impressions.