BELLEVUE - (Bloomberg) — Microsoft Corp. chief executive officer Steve Ballmer said all acquisition talks with Yahoo! Inc. are "done," even after Yahoo CEO Jerry Yang said he would step down. Yahoo fell as much as 13 percent in Nasdaq trading.

"We thought we had something that made sense. Didn't make sense to them. We've moved on," Ballmer, 52, said today at a shareholder meeting in Bellevue, Washington.

He reiterated that a partnership between Microsoft and Yahoo in the Internet-search market is an "an interesting possibility". There are no talks about such a partnership, he said yesterday.

Microsoft and Yahoo are looking for ways to catch up to Google Inc., which attracts more web-search users and advertisers. Yahoo needs to find a replacement for Yang, who rejected a $47.5 billion takeover offer from Microsoft this year. His decision to leave fuelled speculation that Microsoft may renew talks with Yahoo.

Yang, who will step down when his replacement is found, has said he is open to new talks with Microsoft. Google handled almost two-thirds of US Internet searches in September, according to ComScore Inc., a research firm in Reston, Virginia. Yahoo had 20.2 percent of search queries, and Microsoft had 8.5 percent.