It isn't just splashy IPOs that investors are avoiding -- high-flying momentum stocks have been tumbling, too. 

Names like Slack (WORK) - Get Slack Technologies, Inc. Class A Report , Shopify (SHOP) - Get Shopify, Inc. Class A Report , Twilio (TWLO) - Get Twilio, Inc. Class A Report and others have taken a beating in recent days: Since the beginning of this week, Slack has tumbled 13%, Twilio is down 6.5%, Shopify has shedded 3.5% and Okta has lost 8.9%, just to name a few. 

"We are seeing a huge rotation out of high multiple, 'high flying' tech stocks this week for a few reasons," said Jeff Marks, an analyst with Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio. "First, I think the fiasco of the WeWork IPO has caused investors to rethink the frothy valuations placed on similar high growth but low-to-no-profit companies. They all trade at large price to sales multiples and don't have the earnings power for the valuations to fall back on."

Secondly, Marks said, the rise of Sen. Elizabeth Warren, who may favor an increase in capital gains taxes, in the polls likely isn't helping matters. 

"With these tech names being huge winners over the past few years, some investors may be in favor of locking in their gains as opposed to risking a higher tax bill in the future," he added. 

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Momentum stocks that trade at lavish multiples are falling out of favor among institutional investors that often drive broader market moves, added RealMoney contributor James "RevShark" DePorre.

"Large mutual funds, pension funds and hedge funds have decided that they would prefer to own 'value' stocks rather than momentum stocks that have aggressive valuations," DePorre said. "Funds have decided that there is too much risk in those stocks in this environment and they are selling. That selling feeds on itself and drives the stocks even lower."

Other stocks that have taken a spill this week include:

Salesforce and Twilio are holdings in Jim Cramer'sAction Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sells CMCSA? Learn more now.

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