Art Cashin, UBS' director of floor operations at the NYSE, says falling commodity prices signal deflationary pressure, which "has got to be frustrating to central banks all around the world."
Despite record low interest rates and cheap money flooding the globe, oil prices keep tumbling. The problem: Less demand and plentiful supply.
Brent crude and WTI crude both tanked to their worst levels in more than a year Thursday after the International Energy Agency cut 2014 and 2015 global oil demand growth due to weakness in Europe and China.
Cashin and CNBC reporter Bob Pisani were both at the New York Stock Exchange on Sept. 11, 2001. The two agree there has been a sense of renewal in downtown Manhattan since the attacks.
"It's been a marvelous change," said Cashin. "In the weeks and months that followed that [9/11], the only smiles down here on Wall Street were in the photographs on the missing posters that they had around. But we've overcome it."
—By CNBC's Kristen Scholer