In 2018, 188 IPOs raised more than $45 billion, the biggest year for the markets since 2014. It's looking like 2019 could be even bigger--especially when it comes to a dearth of San Francisco-born tech companies going public. Wall Street is, unsurprisingly, jazzed. "I think we've all been waiting for the dam to break loose on that flood of unicorn IPOs," Matt Kennedy, an analyst at Renaissance Capital, which manages IPO-focused exchange-traded funds, told CNNMoney in May.

The unicorns that hit the market this year, including Spotify, Dropbox, and DocuSign, certainly drew some excitement--but it's nothing like the buzz that next year's candidates will likely draw, even if the market continues its end-of-2018 cooling, and as some of the biggest IPO candidates themselves remain extremely unprofitable. A couple of them are pondering unconventional processes as they move toward a public offering, which may not please Wall Street. Here are the 10 startups most likely to go public in 2019, and the stories of how they'll get there, in ascending order of valuation.

10. CrowdStrike

Most online security firms don't make it to a public offering--they're snapped up in acquisition. CrowdStrike, which uses artificial intelligence to prevent attacks on computers, seems to be bucking the trend, as it hired Goldman Sachs to help it prepare for an IPO, likely to come in the first half of 2019, Reuters reported in October. The company is valued at $3 billion.

9. Cloudflare

Founded in 2009 by Michelle Zatlyn, Matthew Prince, and Lee Holloway, this web-services startup began as a concept: "Put a firewall in the cloud." Prince and Holloway had already built a robust spam-fighting architecture, and, with Zatlyn, they managed to scale it without adding latency. Soon, they had a company that actually makes websites load faster. Reuters reported the company had hired Goldman Sachs to bring it to the public markets next year, and could value it at $3.5 billion.

8. Robinhood

This startup lets people trade stocks (as well as options and cryptocurrencies)--and now it wants to be public itself. One of its founders, Baiju Bhatt, said in September that the company would go public in 2019. But it certainly has its hurdles. Chiefly, it doesn't make any money, which is a problem unlikely to be remedied soon. Even so, investors have shown some tolerance for that if the product and market-fit are fantastic. The company is valued at $5.6 billion.

7. Slack

The workplace-messaging company has about eight million daily users--and unlike other enterprise startups, it has achieved a cult-like adoration of the product, and a well-known brand. Its CEO, Stewart Butterfield, is said to be curious about going public through a direct offering, which lets the company sell shares directly to regular people at the rate the market determines, rather than those chosen by bankers, for a price set by bankers. Spotify did this in April, and while it means the company doesn't raise any money from the offering, it is a controversial and interesting practice that could reduce the role, and power, of bankers. Slack is valued at more than $7 billion, after having raised $427 million in August.

6. Rackspace

This isn't Rackspace's first time around the block. The San Antonio-based company that helps enterprise and governments shift their IT operations to the cloud was taken private just two years ago by Apollo, for $4.3 billion. But now, after a debt-financing deal for $800 million to finance a big acquisition, the company could be worth $10 billion in a U.S. listing. Nothing is certain here, though: Apollo hasn't quite decided whether to keep or list the business, according to Bloomberg.   

5. Pinterest

Wait, wasn't Pinterest supposed to IPO, like, a year ago? It was--until it missed its 2017 revenue estimates. Seems everything is back on track, though. In 2018, it reportedly has seen stable ad revenue growth, which could bring it to $1 billion in revenue. And its user growth is outpacing the other social sites, at 15 percent over last year. That's fueling the assumption that it will try again at a public offering. Seems the time is ripe, and the company was most recently valued at more than $12 billion, back in 2017.

4. Lyft

Uber and Lyft have been losing money for years as they battle for market share. But for once, Lyft pulled ahead in its race against Uber in October, by hiring J.P. Morgan to lead its likely 2019 IPO. It filed confidentially with the SEC in December. Its valuation on the public markets could be up to $15 billion.

3. Airbnb

The travel and rental company is hardly a startup anymore. It has 4,000 employees globally, and over the past year it has been working to fill out its whopping $31 billion valuation. It's also reportedly profitable. Interestingly, Airbnb's CEO, Brian Chesky, has reportedly been eyeing the sort of public listing Spotify accomplished last year--one that shifts some of the power away from bankers. He's consulted with Daniel Ek, Spotify's CEO, about how to pull off a direct listing, sources said. And, because the company doesn't need to raise money with a potential IPO, it could be a good candidate for the unorthodox method.

2. Palantir

Could the super-secretive data-mining firm founded by Peter Thiel complete an initial public offering this next year? The Wall Street Journal reported in October that it had attained a valuation as high as $41 billion--more than double the value that private investors had given it. But sources said an IPO was being floated, and that the company had spoken to Credit Suisse and Morgan Stanley about the possibility--though it remains up in the air. The private company may well want to maintain its privacy.  

1. Uber

Of the many, many distinctions Uber has collected in the startup world--most money raised at almost $16 billion, for one--pulling off an IPO while "deeply unprofitable" and simultaneously valued at $120 billion will be its greatest feat. Especially after years of tumult within the company, including multiple executive departures amid accusations of misbehavior and an attempt to clean up the company's image. It filed documents with the SEC the same day as did its competitor, Lyft. There's no word yet on which offering will come first.

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