Setting aside specific problems now facing the economy — like the credit crisis and the continuing troubles in the housing and financial sectors — the math of recovering from downturns of this magnitude is hard to overcome quickly. James B. Stack, editor of the InvesTech Market Analyst, a newsletter in Whitefish, Mont., studied bear market recoveries since 1929; he found that after the most significant downturns — like this one — it has taken more than seven years for stocks to fully recoup losses.

For example, it took 7.2 years after the start of the bear market in 2000 for stocks to reach a bottom and then to climb back to the 2000 peak. After the bear started growling in 1973, it took 7.5 years to return to the high. And after the 1929 crash, equities didn’t return to their previous peak for another quarter of a century.

The current bear market started on Oct. 9, 2007. Based on the average recoveries of the past, the Dow may not make it all the way back to its peak of 14,164 until late 2014. And some market observers say it could take significantly longer.