Check out the latest Roku earnings call transcript.

The holiday shopping season has now come and gone, and it's safe to say that streaming TV platform Roku (NASDAQ:ROKU) had a great quarter. The company has put out preliminary estimates on two of its most important operating metrics -- active accounts and hours streamed -- for the fourth quarter. Though it has never directly disclosed unit sales, instead focusing on building its platform business, it's clear that Roku devices were a popular gift over the holidays.

Here's what investors need to know.

The Roku Channel on a TV

Image source: Roku.

Most active accounts ever added in a quarter

In no uncertain terms, the number of active accounts that Roku has on its platform surged in the fourth quarter. There are now over 27 million active accounts on the platform, up 40% year over year. If you look at the number of active accounts added on a sequential basis, that represents 3.2 million more than it finished the third quarter with. This was the most active accounts that Roku has ever added in a single quarter.

Chart showing active accounts added per quarter

Data source: SEC filings.

Additionally, Roku estimates that there were 7.3 billion hours of content streamed on the platform during the quarter, up 68% compared to a year ago. That puts full-year 2018 streaming hours at approximately 24 billion.

"Strong active account growth and accelerating streaming hours point to consumers' growing enthusiasm for streaming, making Roku America's largest and fastest growing TV streaming distribution platform," CEO Anthony Wood said in a statement. "In 2018, we maintained our leadership in streaming players, licensed smart TVs and TV streaming hours. Roku continues to bring viewers more choice, great value, a compelling user experience -- and lots of TV fun."

Building on platform momentum

Investors were initially disappointed with Roku's financial guidance for the fourth quarter, which calls for a net loss of $4 million to a net profit of $3 million, below analysts' expectations. But the new data show that the company continues to execute well overall with growing the platform and audience. Roku is already larger than any traditional cable operator in the U.S., and is now adding premium subscriptions to the mix.

While there are some challenges with that strategy, there is considerable potential to accelerate growth in platform revenue, which in turn will lead to gains in average revenue per user (ARPU). At the Consumer Electronic Show (CES) this week, Roku also announced several new partnerships with TV manufacturers to integrate Roku OS and The Roku Channel into TVs. Westinghouse Electronics is joining the Roku TV program for the first time, and TCL will make an 8K Roku TV with voice control slated for later this year.

Despite a fourth-quarter forecast that left a little to be desired, Roku is putting up strong gains in its most important operating metrics.