After reporting two quarters in a row of accelerating year-over-year revenue growth, Roku (NASDAQ:ROKU) found its top-line growth rate decelerating a bit in Q3, as revealed in its third-quarter earnings release after the bell on Wednesday. But revenue was still up an impressive 50% year over year, highlighting the company's strong growth trajectory.

As usual, a huge increase in platform revenue, or revenue from the streaming-TV specialist's share of subscription and ad revenue on its platform, helped power the tech company's growth during the period.

Here's a closer look at the results.

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Image source: Getty Images.

Roku Q3 earnings summary

Revenue during the period increased 50% year over year to $260.9 million. That exceeded management's guidance for revenue between $250 million and $255 million and analysts' average forecast for revenue of $256.4 million. This revenue growth rate, however, is down from 59% growth in Q2. The company's loss per share of $0.22 also came in ahead of analysts' consensus estimate for a loss per share of $0.28.

Metric

Q3 2019

Q3 2019

Change

Revenue

$260.9 million

$173.4 million

50%

Adjusted EBITDA

($0.4 million)

$2.0 million

N/A

Data source: Roku quarterly shareholder letters for quarters shown.

Furthermore, Roku beat its own forecast for adjusted EBITDA (earnings before interest, taxes, depreciation, and amortization). Third-quarter adjusted EBITDA was negative-$0.4 million, compared with positive-$2.0 million in the year-ago quarter. Management had guided for adjusted EBITDA during its third quarter of 2019 to be between a loss of $11 million and a loss of $5 million.

Driving the quarter's growth was a 79% year-over-year increase in platform revenue. This put platform revenue at $179.3 million, representing 69% of total revenue. Platform gross profit jumped 59% year over year to $112.2 million.

Advertising was once again the star of the show

As has been the case in recent quarters, advertising continued to be the main driver of Roku's platform business, management said in the company's third-quarter shareholder letter.

Roku said its third-quarter monetized video ad impressions more than doubled year over year. Furthermore, ad impressions within the tech company's Roku Channel app grew at a more rapid rate than impressions across the overall platform, highlighting how the company's namesake channel is contributing to this growth.

"Average annual advertiser spend is increasing on our platform and we are bringing in new advertisers," management said in Roku's third-quarter shareholder letter.

Users are as engaged as ever

The company's user metrics were also impressive. Active accounts grew 36% year over year while streaming hours jumped 68% over this same timeframe. Meanwhile, average revenue per user hit an all-time high of $22.58, up 30% year over year.

Looking ahead

With another strong quarter in the books, management lifted its full-year revenue outlook. Roku now expects total revenue in 2019 to be between $1.098 billion and $1.113 billion, up from a previous forecast for $1.075 billion to $1.095 billion.

But Roku lowered its full-year outlook for adjusted EBITDA to a range between $28 million and $33 million. Previously, management expected adjusted EBITDA to be between $30 million and $40 million. This lowered outlook, Roku said, reflects reinvestment into its business and $5 million worth of headwinds related to its acquisition of demand-side advertising platform dataxu.