For all the economic uncertainty, market spirals and occasional frothiness of the stock market, 2015 was a pretty sober year for initial public offerings.

By the numbers, fewer companies went public in 2015 than at any time since 2009, with 169 companies raising $30 billion in capital, according to IPO research company Renaissance Capital. By contrast, in 2014, nearly 300 companies raised $85 billion.

That's not to say it wasn't a big IPO year for some. Companies involved in business services, energy, and even some consumer sectors, like automobiles and pet food, witnessed a warm welcome from public investors. Humdrum as that may seem, many of them raised hundreds of millions, and sometimes billions of dollars when they debuted.

Here are this year's 10 biggest IPOs. 

10. EQT GP Holdings LP.

Like many of its other energy-producing peers on the IPO list this year, EQT is a limited partnership with holdings in companies that transport natural gas. EQT raised $621 million in May. The company's share price has decreased 20 percent from an offer price of $27.

9. TransUnion.

Best-known for being one of the three main consumer credit reporting bureaus, along with Equifax and Experian, Transunion raised $664 million when it went public in June. Its stock is up 18 percent from an initial price of $22.50. 

8. TerraForm Global.

The green energy entity is an acquisitions spinoff for renewable-energy company SunEdison, which purchases wind, sun, and hydroelectric plants, along with other assets. The Bethesda, Maryland, company raised $675 million in a July offering.

7. Blue Buffalo Pet Products.

Successful public offerings for non-tech, non-energy companies were few and far between this year, which is perhaps what makes this manufacturer of pet food a standout this year. Not only does its claim of making food from real chicken, lamb, and fish differentiate it from many competing brands, but investors seemed to like the story. They priced company shares at the high end, at $20 for the July offering, which raised $676 million for the Wilton, Connecticut, company. It's shares are down about 55 percent year-to-date, trading at $18.

6. Fitbit.

The wearable technology company, based in San Francisco, raised a staggering $731 million for its June IPO. Yet Fitbit faces a packed market, with Huawei's TalkBand and the Apple watch as two prime competing products. Still, Fitbit has something of a first-mover advantage that's likely to keep its share price floating at its current level of around $32, which is more than 40 percent higher than its trading start price.

5. Univar.

The chemical distribution company, based in Downers-Grove, Illinois, is one of the largest such companies in the world, and it raised $770 million in its June public offering. The company's stock is trading down about 23 percent from its initial $22 share price.

4. Ferrari.

The Italian car company, a subsidiary of Fiat Chrysler, raised close to $900 million in October. It got off to a racing start, as they say, with shares pricing at the high end of expectations, at about $52, and jumping about 13 percent in early days. Since then, its stock price has dropped about 6 percent. 

3. Columbia Pipeline Partners.

Like EQT and Tallgrass (below), this is also a limited partnership deal for an electricity and natural gas company that operates 15,000 miles of pipelines stretching from New York to the Gulf of Mexico. In February, when it went public, it was the largest IPO to date for the year. It raised more than $1 billion.

2. Tallgrass Energy GP.

This IPO is one that sums up what Wall Street is best at--turning really complex business structures into easily tradable products. Tallgrass is basically a limited partnership that owns dividend-paying shares of a natural gas company of the same name, based in Leawood, Kansas. Tallwood raised $1.2 billion for the offering in May.

1. First Data.

The 45-year-old payments processing behemoth conducts nearly $2 trillion of credit card transactions for six million businesses annually. Based in Atlanta, First Data raised $2.5 billion in its October debut, and its stock is up about 4.5 percent to date.

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