Thursday's sell-off came amid concerns about iPhone sales and the upcoming iPhone 7. Stocks turned lower Thursday morning as Apple sold off. The Nasdaq was the first of the major indexes to turn negative.
"It's statistically correlated to those indexes," said Kosar of the Nasdaq 100 and S&P. "If Apple drops another 6 to 9 percent, the correlation is likely to have an adverse affect on the broader market."
Read MoreApple hits near 2-year low
Cashin said what ails Apple has spread across technology shares. "None of the techs are doing well. There's a whole rethink of the technology area," he said. "People are beginning to say maybe that's not the growth area we think it is."
Peter Boockvar, chief market analyst at The Lindsey Group, said Apple is one of the top two stocks in the S&P and Nasdaq. "You have to look at it from that perspective," he said. "I've always said it's its own asset class."
"The issue with Apple is it's spilling over into the Apple suppliers, and it very well may be the case that Apple is the greatest technology company since sliced bread," said Boockvar. "If Apple gets such a low mulitple, why should I pay a higher price for grade B companies?"
Boockvar said Apple is over-owned. "A lot of people love Apple," he said. Even after the stock declines, "there's still this love affair with the company."
Apple was trading with a trailing price-earnings ratio of 10. The stock is down 14 percent year to date, and is 32 percent off its 52-week high of $132.97.
Apple was trading around $90.45 midafternoon Thursday. It had broken the $92 level earlier in the week but did not close below it. During Apple's decline, Alphabet surpassed it as the market cap leader Thursday. They are now both close to $494.7 billion.