Microsoft evaluating Yahoo bid -source

(Rewrites first paragraph; adds details on deal; stock move; byline)

By Anupreeta Das

SAN FRANCISCO, April 4 (Reuters) - Microsoft Corp (MSFT.O: Quote, Profile, Research) is evaluating its bid for Yahoo Inc (YHOO.O: Quote, Profile, Research) because the Internet company may have lost value since it made its offer, a person familiar with the matter said on Friday.

The news, first reported by Reuters, sent Yahoo shares down more than 5 percent in extended trade.

A Yahoo spokeswoman declined to comment. Microsoft was not immediately available for comment.

Yahoo has rejected Microsoft's offer, made on Jan. 31, saying it "substantially undervalues" the company.

The bid initially valued Yahoo at $44.6 billion, but is currently worth about $42 billion. Microsoft has been repeatedly trying to engage Yahoo's board in discussions, the person said. But the market has deteriorated and changes in Yahoo's business may have dragged down its value below what it was when Microsoft made its bid, the person said.

Shares of Yahoo fell to $26.81 in extended trade after closing Friday's session up 0.82 percent at $28.36 on the Nasdaq. Microsoft shares gained 24 cents after closing up 0.55 percent at $29.16.