One of last year's hottest stocks is bracing for its first big test of 2019. Twilio (NYSE:TWLO) reports its fourth-quarter financials shortly after Tuesday's market close, and there's going to be a lot at stake for a stock that has nearly quintupled since the start of last year.

The leading provider of in-app communications solutions treated shareholders to a scorching 278% return last year, making it the most valuable company to have more than tripled last year. The good times have only continued through the first few weeks of 2019, and we're now 386% above where we were at the start of 2018.

The expo entrance for Twilio's 2018 Signal conference for developers.

Image source: Twilio.

Cracking the code

Twilio stock kicked off the new trading week by opening at another all-time high on Monday, but now it will have to earn its recent gains. Expectations are high heading into Tuesday afternoon's report, and there isn't a lot of room for error when you are pretty much the market darling of tech stocks over the past year and change. 

Analysts are holding out for another period of monster growth. They see Twilio's revenue soaring 60.5% to hit $185 million for the quarter. This is a slowdown from the 68% top-line spurt it scored in its previous quarter, but this isn't a dream ender. Revenue growth had actually accelerated through 2018 -- going from 41% in the fourth quarter of 2017 to 48%, 54%, and then 68%, respectively, in the first three quarters of last year. Easing on the accelerator while still cruising north of 60% would still make this Twilio's second strongest period of top-line growth in two years -- and we know how well the stock has responded in that run. 

Wall Street's holding out for an adjusted profit of $0.04 a share, reversing a small deficit from the same quarter a year earlier. Twilio's been able to blast through analyst profit goals with ease, exceeding expectations by 42% or better every single period over the past year. 

Twilio has made itself indispensable to most of the leading mobile apps, offering users the ability to communicate with developers or perform basic functions without every having to exit the application. The number of developers on Twilio has soared with over the past year, with active customer accounts rising 32% to 61,153 active customer accounts as of the end of September. Revenue continues to outpace the active customer count, as users lean on in-app communications that feature more and more. Twilio has also gotten better about upgrading the platform and rolling out new features like Flex, the first fully programmable cloud contact-center solution that it introduced in 2018.

Check out the latest Twilio earnings call transcript.

You don't pop nearly fivefold over the past 14 months without introducing helium into the stock market. Twilio shares aren't cheap by most measuring sticks. It's fetching an enterprise value that is nearly 25 times its trailing revenue, and that's tame compared to its earnings multiple as the company is just starting to come into its own on the bottom line. The momentum is there, but that will require another monster quarter out of Twilio. The in-app rock star has been up to the challenge before, but it obviously has never stepped up to the podium with its stock as high as it is right now.