S&P 1,810? Trend Says it Could Happen in a Year

Now that the Standard & Poor's 500 has gained more than 100 percent off its bear market lows, history suggests the index could keep rallying another 450 points or so.

Sam Stovall, S&P's chief equity strategist, says the median additional gain for the broad index after it doubles its low is 33.7 percent in the following 12 months, before hitting another bear market.

That would take the S&P 500 to a lofty 1,810 mark.

Of course, that's only history, and this market has been nothing if not unpredictable.

But the S&P 500 rally has overcome some pretty stiff resistance thus far, so who knows?

According to Stovall's research, continued advances off doubling rallies lasted as short as four days and as long as four and a half years.

Those gains ranged from 0.7 percent after the 2002-07 bull market, to 160 percent in the 1990-2000 bull.

Timing appears to be everything.

"In general, the deeper and longer-duration bear markets saw an increased likelihood of a 100% move during the subsequent bull market," Stovall wrote in a note to clients, noting that the doubling usually followed a bear that lasted 20.4 months—a bit longer than the downturn that saw the March 2009 lows.

So what does this trend foretell of the chance the S&P has of hitting 1,810?

Even Stovall is a bit skeptical, observing that "as Buddy Holly once sang, "That'll be the day.'"