"Stocks can remain at rich valuations as long as a 'fear' catalyst doesn't arise from" interest rates, employment, or inflation, an analyst said.

In a reminder that stretched valuations make for poor timing signals, Piper Sandler strategist Michael Kantrowitz observed in a Monday note that the S&P 500 is overvalued to the tune of around 8% relative to the firm's fair-value price-to-earnings ratio model.

Michael Kantrowitz, chief investment officer at Piper Sandler, joins CNBC to discuss outlooks on over-valued markets, how he's positioning, and more.