Yahoo Inc. faces pressure to invest more in social networking as it sees a dramatic shift by Web audiences to sites like MySpace, YouTube and Facebook, analysts said on Wednesday.

Yahoo may become more aggressive in buying a fast-growing social network, analysts said, amid speculation it is interested in smaller MySpace rival Facebook.

That pressure is already high since Web rival Google Inc. agreed to buy video sharing site YouTube for $1.65 billion last week.

“Facebook is only of value if Yahoo pays the right price,” said Jim Friedland, analyst with Cowen & Co., referring to reports the two companies discussed a $1 billion price tag.

After years of charging premium ad prices to reach users of its Web sites and communities, Yahoo now blames a weaker growth outlook partly on a glut of competing advertising on the hugely popular social networking sites.

The deeper risk for Yahoo is seeing its vast base of users consolidate or even contract as impatient Internet audiences find new corners to frequent on the Web, drawing away even more advertiser dollars, analysts said.

Tags: Yahoo, MySpace, Facebook, YouTube, Social Networking