Private market start-ups face a tough fundraising environment, and up to a third of them may not be around a year from now, Theresia Gouw of Aspect Ventures said Friday.

"There's no question that we're in a private market valuation bubble," the venture capitalist told CNBC's "Squawk Alley." "There's 117 privately valued billion-dollar-plus companies. ... There's no question those companies are worth less than their public market counterparts."



Investors shouldn't expect to see a massive, one-day selloff in the vein of the 2000 dotcom fallout, she said. Start-ups today are staying private longer, so the problem will not manifest in spiraling stock prices, but an inability to raise enough money to survive.



Recent stock market volatility has dried up late-stage funding in particular, she said. With many portfolios under water following last month's equity selloff, public market investors that once turned to mature private market start-ups for yield are taking a pause.

"If they are already fully funded—they've raised $5 billion, in the case of Uber—they'll do just fine, and they'll just stay private until they can weather the storm. But a lot of those guys are going to get caught short with not enough money to see their way through," she said.