The volume of initial public offerings has picked up slightly in the second quarter after the historically slow first three months of the year. Nevertheless, those waiting for a stampede of "unicorns" to hit the new issue market will likely have to wait till 2017, said Jackie Kelley, Americas IPO markets leader at EY.
 
"The unicorns are lining up and definitely coming. I think we will see one this coming quarter, but 2017 is our year for unicorns," said Kelley.
 
Though there have been some bigger IPOs of late including U.S. Foods (USFD - Get Report)  and MGM Growth Properties (MGP - Get Report) , overall activity has been slow compared to last year. This quarter has had 32 IPOs, raising $6 billion. In the second quarter of 2015 the market saw 72 IPOs drumming up $14 billion in proceeds.
 
Kelley said VC- and PE-backed companies have been pretty much the driver for 2016 U.S. IPOs, and she expects that to continue throughout the rest of the year. Lower-than-normal IPO returns in 2015 are another reason for the quiet IPO market, in her opinion.

"We need to see stronger IPO returns before we actually see a real window opening," said Kelley.

That could come next week when cloud communications company Twilio is scheduled to start trading. Twilio is slated to end Silicon Valley's tech IPO drought next week with a $130 million market debut. The San Francisco-based "unicorn" set terms for its pending IPO, disclosing that it plans to offer 10 million shares priced at $12 to $14.

"This is the last quarter to get out before the summer slowdown. We anticipate the window will close in fall until the end of the year," said Kelley. "Once you hit September, that's right before the election and companies will want more certainty in markets and regulation before an IPO."

Kelley added that the election does not necessarily create uncertainty for companies, but rather the capital markets.

"It is best for companies to IPO when volatility is low and regulation and policy are predictable. This is not the current market," said Kelley.