As stocks fell on Thursday, with Wall Street extending its worst start to October in three years, veteran trader Art Cashin told CNBC the selling may be overdone.
Cashin, director of floor operations at the New York Stock Exchange for UBS, pointed to news that the European Central Bank left interest rates unchanged. Though ECB President Mario Draghi said the central bank would purchase assets for two years or more to lift inflation and increase economic growth, his comments failed to inspire investors, Cashin said.
"Strangely, there is a history of very weak October 1 being followed by rebounds on the second," Cashin said on "Squawk on the Street." "But when Draghi came in with an empty hand, things have changed here, they'll take us down with them."
Still, Cashin said the market is "technically oversold." He recommends investors monitor technical indicators.
Selling began to accelerate on Wednesday once the index fell below the 1,952, a key technical level that has served as resistance in Thursday's session, Cashin said. The S&P fell as low as the 1.941 level on Wednesday, he said.
"The key today is, do we take out yesterday's lows?" Cashin said Thursday. "You trade below [1,941] and people are going to say, 'Utt-oh, here we go again.'"
—CNBC's Kate Gibson contributed to this report.