Here's why the IPO market is heating up

Employees and sellers of the online marketplace Etsy stand with CFO Kristina Salen on the floor of the Nasdaq as the company went public on April 16, 2015.
Getty Images

The IPO market is finally starting to get going, and next week will be the biggest week of the year. Roughly 14 companies are slated to go public and will likely raise north of $2 billion.

It's been a lackluster start. There's been 82 IPOs this year, about 40 percent below where we were last year.

Why is the market finally heating up? The single most important factor is positive returns for investors. With the overall market relatively healthy, IPOs have also done well. The Renaissance Capital IPO ETF, a basket of roughly 60 recent IPOs, is approaching its April historic high.

For others, there may be a simple calculation that now is the time to take the company public, before the Fed begins raising rates later this year.

Read More Are hot start-ups available to retail investors?

The upshot: June could be one of the biggest months for IPOs in years. Perhaps as many as 34 will price, the most in a single month since 1999.

"It's like somebody pressed the IPO reset button," Kathleen Smith from Renaissance Capital said.

What's impressive about next week's crop of IPOs is the breadth of the offerings. There's something for everyone.