In a speech at the Cannes Lions advertising festival today (June 24), he refused to rule out that he was interested in a search partnership with the second-biggest search engine.
“We remain open to a partnership with Yahoo!,” he told the audience.
His latest comments come despite speculation earlier this month that Yahoo! was no longer interested in partnering with Microsoft.
“A partnership between the two companies makes sense in order for us to provide a better product based on advertiser interactions. At the moment, they do more search ads and keyword-related ads on Google,” he says.
Last year, Microsoft made a failed attempt to buy the search engine company for $44.6bn (£22.4bn) in cash and shares.
Ballmer maintains that it no longer has any interest in acquiring the search engine business.
He says his ideal environment will be for the internet to become a healthy playing ground for advertisers, and he predicts that all content will move online in the next ten years.