Wall Street has IPO fever.

Sixty-six companies have gone public so far this year, including major winners Beyond Meat, Zoom and Crowdstrike, and seven others are set for their own floats this week. Surging market debuts have also more than doubled the performance of the Renaissance IPO ETF this year.

Kathleen Smith, Renaissance Capital principal and the brain behind the IPO ETF, says healthy demand for these upstarts should keep the market red-hot this year.

"The important theme here is called growth, and investors are looking for growth companies in a slow-growing economy," Smith said on CNBC's "ETF Edge" on Monday. "A lot of their valuation is based upon future earnings, and the discount on future earnings gives a higher present value with lower interest rates. So, we are in a very positive environment for growth equities, which are a large part of the types of equities in the Renaissance IPO ETF."

The IPO ETF holds recent U.S.-listed stocks within three months of their debut and sells after two years. Its top holdings include Stitch Fix, Dropbox and DocuSign, among a basket of others. Those three stocks trade at relatively high multiples, DocuSign by as much as 197 times forward earnings. However, each has outperformed the market as investors show a willingness to pay higher valuations for expected future growth.

Their future performance is contingent on whether they can deliver on those high expectations, says Smith.

"That was the problem we had with Snap way back when — that company overpromised and underdelivered. We need the companies to underpromise and overdeliver," she explained.

Snap tumbled following its early 2017 IPO as worries over subscriber growth and C-suite turnover set investors on edge. From its March debut trading at $24 a share, the stock slumped 80% to bottom out at all-time lows last December.

Smith sees a stronger performance ahead for some of the top IPOs this year.

"We're talking about technology, new inventions, we're talking about real growth. Even with Chewy.com, which is a little bit more of a traditional company, it had a pretty high gross rate and [is] the dominant player in online e-commerce for pet supplies," she said.

Chewy.com has rallied 53% since making its market debut on Friday.

The IPO Renaissance ETF, which does not yet hold Chewy, has soared 35% this year, more than twice the gain on the S&P 500.