Every year has its share of initial public offerings (IPOs). But some have a cast of companies set to launch that captures the public's imagination, and 2019 is poised to be such a year. Not only are many of these businesses well-known to investors, but recent changes in the process have convinced several of them to take a nontraditional route to listing.

Let's look at the latest developments for four of the most high-profile companies getting ready to take the public stage.

A woman glancing at passengers in the rearview mirror while driving

Image source: Uber.

1. Uber

Uber is the undisputed leader in the emerging ride-sharing market, and it made a confidential filing with the Securities and Exchange Commission (SEC) late last year, within a few days of competitor Lyft. After its most recent infusion of cash, Uber was valued at about $72 billion, though it's hoping that Wall Street ups the ante to about $120 billion when it goes public.

Its fourth-quarter 2018 results give investors a taste of what's to come. Gross bookings -- what Uber collects before drivers are paid -- grew to $14.2 billion, up 37% year over year. Revenue climbed to $3 billion, up 24% compared to the prior-year quarter, though it declined to 21.3% of gross bookings, down 190 basis points. Uber generated a net loss of $865 million, including a one-time tax benefit; otherwise the losses would have been $1.2 billion. Those types of steep losses are likely to continue as the company keeps expanding internationally.

Uber controls roughly two-thirds of the ridesharing market. The company will provide additional details on its outlook as it moves closer to its public debut.

A lighted Lyft logo mounted on the dashboard of a car with driver and passengers laughing

Image source: Lyft.

2. Lyft

Lyft recently disclosed financial details in advance of its long-awaited IPO, and it now appears the company will go public ahead of its main rival, Uber. Lyft said in its filing that it controlled about 39% of the U.S. ride-sharing market in the fourth quarter, up from 22% in December 2016. The company will list on the Nasdaq using the ticker LYFT.

The financial data supplied by the company was pretty much what you'd expect from a start-up investing heavily to grab market share. Lyft produced revenue of $2.2 billion in 2018, up 103% year over year, while generating a net loss of $911 million, 32% worse than its $69 million loss in 2017.

Lyft's reported rider metrics have been improving. The number of active riders increased to 18.6 million in the fourth quarter, up 48% year over year, while revenue per active rider climbed to $36.04, up 32% compared to the prior-year quarter. Additionally, the number of rides jumped to 178 million, up 53% year over year.

A screenshot of the Slack app on a Windows computer

Image source: Slack.

3. Slack

The company behind the popular workplace chat service and communication tool hasn't publicly confirmed its plans, but there have been several reports indicating that Slack plans to go public in the first half of 2019. It's reportedly opting for the nontraditional and far less familiar direct public offering (DPO), following in the footsteps of music-streaming service Spotify, which took that approach last year.

This method allows the listing company to raise money directly from the public and save the millions typically charged by investment banks. Companies choosing the DPO route don't sell new shares; the process instead allows existing investors and employees to cash in on their early investment. This method can be particularly appealing to a company that is profitable and doesn't need to raise a large amount of capital.

Slack raised more than $1 billion in various funding rounds since 2013, and was valued at $7.1 billion as of last August. Interestingly, the company hired the same trio of advisors -- Goldman Sachs, Morgan Stanley, and Allen & Company -- that guided Spotify to its launch.

A fireplace surrounded by books, plants, and paintings

Image source: Airbnb.

4. Airbnb

The world's largest accommodation-sharing site, Airbnb does for houses and apartments what Uber and Lyft do for cars. Homeowners offer up rooms or entire homes to travelers looking for a place to stay besides the traditional hotel options. Airbnb is reportedly readying for its public debut, and may also be eyeing the nontraditional DPO. In mid-2018, CEO Brian Chesky said the company would be "ready to IPO next year, but I don't know if we will." The long-vacant office of chief financial officer was filled late last year, a necessary step before any public offering.

Airbnb revealed last month that it has posted two successive years of EBITDA (earnings before interest, taxes, depreciation, and amortization) profit. The popular platform is now available in more than 1,000 cities, and the company projects that it will have cumulatively served over 500 million guests by the close of the first quarter. Previously, Airbnb reported that the third quarter of 2018 was its "strongest quarter ever," it had generated "substantially more" than $1 billion in revenue in that period, and it had reached more than 400 million guest arrivals since the company's founding. That shows accelerating growth, with the company expecting to host nearly 100 million guests in about six months.

In its most recent round of funding, Airbnb was valued at about $30 billion.