Yahoo!, the web portal, was expected to give an update on the state of the online advertising market last night in keenly anticipated fourth quarter results.

Investors were nervous ahead of the results amid signs of a sharp slowdown in the US economy in general and advertising revenue in particular. Almost all of Yahoo!'s top line sales come from advertising.

Wall Street analysts have raised concerns that more than 40% of group revenue is derived from the struggling dot.com sector. Several have downgraded the company in recent weeks amid expectations of a weakening outlook.

Since reaching a high of more than $225 last spring, shares in Yahoo! have lost more than 90% of their value. They were up slightly at midday yesterday at about $30.

According to a First Call survey, analysts' consensus was that Yahoo! would report fourth-quarter earnings of 13 cents per share and revenue of about $315m.

For the full year, revenues are expected to reach $1.1bn, up from $588m in 1999. Analysts also expect Yahoo!, one of the few profitable internet companies, to double annual earnings.

In a research note published earlier this week, Henry Blodget, the once bullish internet analyst at Merrill Lynch, said he expected overall online advertising spending to be flat at about $8bn this year. This marks a sharp deterioration from his previously held view of a 30% growth rate.