Everyone knows that advertising suffers in tough economic times, but the speed and severity of the current slowdown continue to shock. Few media groups dare to predict more than a quarter ahead, but News Corp.’s forecast for 2009 confirms bleak times.

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News Corp.’s forecast hit prompted investors to slash a quarter off its market capitalization. Global ad spend is expected to decline 4.3% next year compared with 7% growth in 2007, according to Morgan Stanley. But that guess may be optimistic. Auto makers make up 15% of total spend, and News Corp. says General Motors Corp.’s advertising spend is down 50%. Finance, pharma and retail are all cutting back across all mediums.

It’s especially hard for print, supporting the view that this medium is in terminal decline. Barack Obama’s landmark election may have given newspapers a one-day circulation boost, but the summer Olympics failed to provide the “Beijing bounce".

No UK publication grew monthly sales in August. And in the ongoing rapidly evolving global financial crisis, newspapers seem too often behind the curve.

Broadcast advertising has also fallen off a cliff. News Corp.’s Fox Television Channels reported a 70% operating profit decline in the quarter, twice as much as some analyst expected.

Results at UK’s ITV core channels suggest double-digit declines in TV revenues. In Germany, ProsiebenSat said it can’t rely on a single core stable market, at least until the end of this year.

Record hits to News Corp.’s WSJ.com and CNBC suggest online is benefiting from declines elsewhere, but the model is hard to monetize. ITV delivered third quarter online revenue growth just one-sixth of estimates. And flagging demand for Internet ads has left Yahoo Inc. begging software giant Microsoft Corp. to snap it up.

Advertising agency valuations are now pointing to nothing less than an advertising depression. European agencies such as WPP Group Plc. are already trading at around seven times forward earnings, one-third below previous troughs.

If media is a harbinger for the economic future, the wider economy is in trouble.