1,450 on the S&P? Here’s why it’s not crazy: Technician

History of a bear market
History of a bear market   

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The S&P 500's recent 13 percent decline has investors aching to know when the selling will end. But the technician who called the downturn toward 1,800 says this is just the beginning. The S&P was at 1,855 on Tuesday.

"We are no longer in an uptrend. What we know is that our Ebola low was 1,820. We violated that low last Monday, and now we have a well-defined series of lows from which in principle, a bad break is often the conclusion," Cornerstone Macro's Carter Worth told CNBC's "Fast Money" traders on Monday. "The path is lower by my work."

Carter uses two technical measures to define two possible outcomes if the S&P continues to fall.

The first is by looking at the S&P's entire bull market run since the 1980s.

If the S&P 500 were to stay within the tight range it has traced in recent years, the next stop for the index would be 1,575.

But Worth says that if history is any indication of what could come of this bear market, it could be much worse.

There have been 30 declines of 20 percent or more dating to 1921, he said. The mean and median of those declines straddle 32 percent.

"If we do a 32 percent decline, and our high was 2,134 in May, that would give us 1,450 [on the S&P 500]," he said. "We're thinking much lower. It's a bad tape. There's something wrong."