As high-flying momentum names sold off Monday, it was time for investors to watch what happens next in small-cap stocks, Private Advisor Group's Guy Adami said on CNBC.

The and Russell 2000 indices ended the day lower, along with names such as Tesla, Amazon and Netflix.

"I still think the IWM goes to 108, and then I think you have to see what happens if and when we get there in terms of what it does to the S&P. But I don't think it means it's the death of the small-cap," he said on "Fast Money."

The tell, Adami added, would be in the Russell.

"I think 108 is sort of the line in the sand," he said. "I'm of the belief that if it does get there, it's going to trade right through it."

Adami also pointed to MobilEye's rise as a sign that other stocks will retain strength, with opportunities presenting themselves in names such as Netflix.

"I was really surprised by how bad the market was," said Karen Finerman of Metropolitan Capital Advisors. "With the here at 13.69 … it's in no-man's land. I wouldn't be selling volatility here. … I think this gets worse before it gets better."

OptionMonster's Pete Najarian said that it wasn't necessary to read too much into the day's action.

"This is only a single day," he said, adding that such exchange-traded funds as SMH, and ended higher. "So, there's a lot of elements to this market that have been behind this stock market moving to new highs that continue to hold on. There are areas that are definitely under pressure, no doubt about it."

Triogem Asset Management's Tim Seymour said that a rally in the U.S. dollar was adding to volatility, not to mention the Federal Reserve's meeting last week, Scotland's independence vote, Alibaba's initial public offering and a triple witching on Friday, which saw contract expirations for stock index futures, stock index options and stock options.

"And just from a market standpoint, we typically tend to see the market trade off after the Fed and after triple witching," he said. "So, to go out and sell everything today and say momentum is dead, no. But to say that a lot of stocks are starting to sell together, absolutely."