This year's hottest large-cap stock has some pretty big gains to justify this week. Roku (NASDAQ:ROKU) reports its third-quarter results after Wednesday's market close, and the streaming-video pioneer has plenty of wind beneath its wings.

Roku stock has soared 359% in 2019, more than double the return of any stock commanding a market cap north of $10 billion. The stock has become a market darling as a way to cash in on the streaming revolution without having to pick winners among the growing number of digital services. Roku's growing its audience, boosting its platform's engagement, and laughing all of the way to the bank with its improving monetization skills. The challenge now is for Roku to live up to the hype.

Roku hub running on an Insignia smart television.

Image source: Roku.

Great expectations

There's an abundance of tailwinds driving Roku's success in 2019, but the immediate concern is the need to at least live up to if not exceed its earlier guidance. Roku's early-August outlook was calling for a modest deficit on $250 million to $255 million in revenue for the third quarter, a 46% year-over-year top-line surge at the midpoint of that range.

Roku has been routinely raising the bar, lifting its full-year guidance with every quarterly update. It's fair to say that the bare minimum for a stock that has more than quadrupled in 2019 is to once again lift its forecast heading into the holiday shopping season, especially with so many hyped-up streaming services launching in November.

Roku's rolling. It's this year's hottest growth stock among large caps, and the driver here is the series of stackable metrics that translates into monster top-line gains. There are now 30.5 million active Roku users, 39% more than those huddled around their Roku-fueled TVs a year earlier. Roku has more than held its own in promoting its dongles and set-top devices that welcome viewers into its hub as a gateway to thousands of available streaming services, but its operating system is also the leading platform for smart TV manufacturers.

Those 30.5 million accounts streamed 9.4 billion hours of content during the second quarter, a jaw-dropping average of 3.4 hours of viewing a day. With consumption up 72% on that 39% increase in Roku homes, we're seeing average revenue per user also climb, up 27% over the past year.

The caveat in all of this positive buzz is that the market's already holding out for greatness. The consensus analyst target calls for $256.1 million in revenue for the three months that ended in September, above even the high end of Roku's own guidance. In order to justify its scintillating year-to-date returns, Roku will have to at least match the 48% top-line surge that Wall Street pros are targeting. It also wouldn't hurt to once again jack up its full-year guidance with a rosy outlook for the upcoming holiday season. The weather may be cooling down, but Roku's stock can't afford to follow suit.