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.
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"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