Don't run with the bulls quite yet

All of a sudden, it's a bull market. The Dow Jones Industrial Index has risen by 21% since March 9, just crossing the traditional 20% threshold that some chart-watchers use to separate a mere rally from the real thing, But this three-week old may not live to a ripe age.

The previous Dow (INDU) rally started after the November 2008 rescue of Citigroup (C, Fortune 500), lasted until the New Year and came a mere 0.8 percentage points short of qualifying as a bull market - before yielding to a 28% rout. The current recovery has largely been a vote of confidence in a subsequent U.S. banking system rescue, along with massive government help.

Will this upward market movement prove more durable than the last? Mathematically, it has the advantage of starting from a much lower base. From Thursday's close, the Dow will have to rise a further 14% just to match the 2009 high, hit on January 2.

The economic case is less clear. True, after the nationalization of financial risk through guarantees and money-printing, panic over a possible imminent financial sector collapse looks overdone. And while GDP in the first quarter of 2009 looks to have been substantially lower than in the fourth quarter of 2008, the pace of decline seems to have slowed.

But the global downward economic momentum remains strong. The International Monetary Fund doesn't expect growth to return until "the course of 2010". While waiting, profits are going to be slaughtered.

Profits at non-financial U.S. corporations fell by 9% in 2008. In severe recessions, the average drop is more like 25%, according to BNP Paribas. Globally, the rate at which analysts are cutting their earnings forecasts - a fairly accurate indicator of current profit, according to Société Générale - suggests a 40% decline for quoted companies this year. That suggests investors are paying 20 times current earnings for stocks.

The bull market will only last if it can trample over a thicket of terrible earnings announcements. That is a lot to ask from investors who have not yet fully recovered from a too-long series of financial shocks.