The late summer tailspin for the stock market has created enough concern among investors that even Santa Claus probably won't be able to save 2015 from ending the year lower, economist David Blitzer said Wednesday, the final day of the third quarter.
"You're going to need some really big catalyst to get going, and I think there's still too much anxiety," Blitzer told CNBC as the Dow Jones industrial average, the S&P 500 and the Nasdaq composite struggle in correction territory, measured by a decline of 10 percent or more from recent record highs.
Wall Street did open strongly higher Wednesday, as investors wondered whether equities might test their most recent lows on Aug. 25, when the market plunged on heightened concerns about China and global growth.
Billionaire investor Carl Icahn, in a self-produced new video called "Danger Ahead," expressed concerns this week about stocks, saying the market could go down "a lot more" as investors come to grips with bubbles exacerbated by the Federal Reserve's near-zero percent interest rate policy.
Blitzer, chairman of the S&P Dow Jones index committee, told CNBC's "Squawk Box" he's not as concerned about stocks as Icahn is, but said he's a "little worried."
"The thing to be really concerned about is debt levels. Yes, some of that comes from low interest rates," Blitzer said, referring to soaring government and increasing consumer-debt levels.
He said the tech boom of the late 1990s and bust in early the 2000s caused only a mild recession because debt levels were not that high. "Most of it was in the stock market where you can't borrow more than half the value on margin."
But the run-up to the 2008 financial crisis and the Great Recession that followed was exacerbated by crushingly high debt. "It was all on houses, people buying houses with no money down, which was 100 percent leverage, and that was really severely damaging," he said.