Valuations on the broader market and popular stocks such as Nvidia (NVDA) just feel too hot, pros are starting to chatter about.

"There's definitely some level of froth [in markets]," Fed Watch Advisors founder Ben Emons told Yahoo Finance Executive Editor Brian Sozzi on Yahoo Finance's Opening Bid podcast. "There's a lot of liquidity in the market. You see speculation through these meme stocks — so that's happening."

Emons isn't alone.

Morgan Stanley's top strategist Mike Wilson warned this week of a 10% pullback in stocks ahead of the election. Wilson is among the experts on the worried about current stock valuations.

And Nvidia's stock caught a rare downgrade to neutral by New Street Research on valuation concerns.

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