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.

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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.

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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.

The biggest deal of the week will be TransUnion, the giant credit analysis company, with a $650 million offering, one of the largest of the year.

But there's a lot more. One of the most interesting is Milacron Holdings, which makes plastics processing equipment. I can't remember the last time I saw an IPO for a company in the capital equipment space. The company has emerged from a 2009 bankruptcy filing.

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There's also Wayne Farms, a broiler-chicken processing company that supplies chickens to Chic-fil-A, Costco, and others.

Not surprisingly, there are three cloud-computing companies:

1. Alarm.com (home security)
2. AppFolio (rental property management)
3. Xactly (employee and sales performance management)

There are four health-care firms, including two biotechs:

1. Glaukos (glaucoma treatment products)
2. Catabasis Pharmacuticals (technology for improving drug efficacy)
3. Seres Therapeutics (microbiome therapeutics)
4. Lantheus Holdings (diagnostic medical imaging agents)

And finally, there's a surprise, with three energy-related companies:

1. Green Plains Partners (ethanol and fuel-storage tanks)
2. CNX Coal Resources (Coal MLP, with 10 percent dividend!)
3. Gener8 Maritime (seaborne crude-oil transportation).

I say a "surprise" because energy stocks, which were a hot space in 2014 (particularly Master Limited Partnerships, or MLPs), have all but evaporated this year.

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Also on the docket: Sungard, an accounting and software firm with $2.8 billion in sales, and Blue Buffalo, the largest maker of all-natural dog and cat food.

Go ahead and laugh about all-natural pet food, but the company has $940 million in sales. It filed nine days ago, which means it has a shot of going public in the next few weeks.