Ballmer has said repeatedly in recent weeks that Microsoft is no longer interested in acquiring all of Yahoo, but that the company is open to a narrower deal. Adding Yahoo's search operations to its MSN and Live Search network could help Microsoft close the gap with industry leader Google in the lucrative Internet search market.
Yahoo is currently the No. 2 player, with Microsoft a perennial third despite recent acquisitions -- including a $1.2 billion deal for Norway's Fast Search & Transfer -- meant to bolster the company's position.
Adding to speculation that Microsoft is intent on integrating Yahoo's search operations is the company's hiring last week of Qi Lu, who was Yahoo's engineering VP for search and advertising technology. Microsoft named Lu head of its online services unit.
Yahoo shares have been volatile in recent weeks as investors react to the rumor mill and apply Kremlinesque analysis to even Ballmer's most casual comments. The stock plunged more than 13% on Nov. 7 after Ballmer told fellow attendees at a business lunch that he was no longer interested in acquiring Yahoo outright.
"We made an offer, we made another offer, and it was clear that Yahoo didn't want to sell the business to us and we moved on," said Ballmer, according to The Associated Press. "We are not interested in going back and relooking at an acquisition," Ballmer said.
Ballmer made the comments in Sydney, Australia.
Microsoft earlier this year offered to purchase Yahoo for $31 per share, but talks between the companies ultimately broke off.
Yahoo shares rose 5.52% Friday to close the week at $11.66.