Wall Street veteran Art Cashin told CNBC on Wednesday that tech stocks have provided the vast majority of gains in the market recently, and that makes him "wary."
"That leadership all alone usually can't last forever," the director of floor operations at the New York Stock Exchange for UBS said on "Squawk on the Street." "After a while, you get so much money put into it and everything else is kind of lagging behind."
As of Wednesday, the tech-heavy Nasdaq was up more than 2 percent for the month and on track to record a seven-month winning streak, its longest since 2013. U.S. equities fell Tuesday, but a rise in tech stocks helped cap losses.
The technology sector has been one of the biggest beneficiaries of Donald Trump's presidency, rising around 20 percent this year, with Apple, Amazon, Facebook, Microsoft and Alphabet hitting new all-time highs.
Amazon briefly traded crossed $1,000 per share on Tuesday, and Apple pushed its market value to more than $800 billion earlier this month. Cashin said traditionally when you get the kind of action seen in the market, it begins to stall or slow down.
"Two to three weeks after this kind of action ... (it) does not usually produce a big rally," he said. "The market confounded a lot of those old fogies last week because this should have begun the stall probably as early as in the middle of last week and they continued into the holiday weekend."
Cashin said traders are starting to get "itchy" because things have been "too quiet in Washington" over the past five days as the Senate is on its Memorial Day recess.