Microsoft's bid for Yahoo took on the air of inevitability Monday, even as the Sunnyvale search firm's board of directors officially rejected the offer.

That decision, first reported during the weekend, was widely viewed on Wall Street as an effort to get Microsoft to raise its $44.6 billion, or $31 a share, proposal - or at the very least give Yahoo time to look at other options. Yahoo's stock rose 2 percent in regular trading to close at $29.87, up 67 cents.

"It's good negotiating tactics to try to get a higher price from Microsoft," said Laura Martin of Soleil Securities Group. "But if they really reject the offer, they are going to have a litany of shareholder lawsuits. It's clear there are no other bidders for anything close to this price."