The S&P 500 could be in the early innings of a correction, professional day trader Lawrence Altman said Friday on CNBC.
"It seems like in all uptrends, the market never goes down very much, but in all downtrends, you get these vicious rallies," he said. "They go up very quickly on no volume, and you just have to be patient."
In an appearance two weeks ago, he said the market appeared to be getting "tired."
"It seems to me that there's an enormous amount of complacency because each time we have a correction, it becomes shallower and shallower," he said March 14. "I think we're on the verge of a substantial correction."
After continued losses in the major indexes on Friday, Altman said that the correction could get worse in the near term.
"I agree with people talking about, 'They rotated to safer things,' but if the market's really going to have a correction, and the action is sort of leading to that, they don't really leave anything alone," he said.
"We took out last month's high, which was an all-time high, last week, and now we're below last month's low. That's a pretty significant thing, off contract highs. If it happens in a week, that's significant," Altman added. "But if it closes below 1,830, the S&P, for the month, you're definitely going to test the 200-day moving average. And, you know, who knows where we're going to go from there?"
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Altman said he viewed the market's recent behavior as "Stock Market 101."
"The first thing I ever learned was that it's a discounting mechanism. It goes up in anticipation of good things. When things actually become good, that's when it usually has a correction. And if you're really bullish on the long term, you want the market to have a correction," he said.
—By CNBC's Bruno J. Navarro