This is not like the 90s tech mania because these companies have dependable profits, says SunTrust

Traders work at the New York Stock Exchange in New York, the United States, March 16, 2020.
Michael Nagle | Xinhua News Agency | Getty Images

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A handful of tech names have led the market's rebound since the coronavirus-induced sell-off in March, and as these companies become an ever larger share of the overall market, some investors have started to sound the alarm over potential risks.

"Concerns of another technology bubble are rising," said Keith Lerner, chief market strategist at SunTrust, in a recent note to clients. "There is also growing concentration risk, with the top five stocks now accounting for 22% of the S&P 500 Index."