The launch comes nearly a year after rival networks were launched and eight months after Softbank executives began hinting their network was coming soon.
"We have been focused very much on foundation-buy side," said Caroline Vanderlip, chief executive of Softbank Interactive Marketing, referring to the major Web content sites that Softbank represents to ad agencies. "We think it's the right time to be in the market."
Key to the network's launch was Softbank's March purchase of World Wide Media, the advertising business of Australian ISP OzEmail, according to Doug Wintz, Softbank Interactive's vice president of network development.
"We own and operate our ad-serving technology as opposed to doing it through a third party," Wintz said. "That makes our business plan a lot more sound."
The sites within Softbank's ad network today get 45 million impressions per month, and Vanderlip said the goal is to boost that number to 100 million by year's end by adding new sites to the network.
Softbank's ad sales force of 60, who have sold the foundation sites to date, also will sell the new network.