Roku Inc. (ROKU) - Get Report shares traded sharply higher Thursday after the video streaming device maker posted a narrower-than-expected first quarter loss and boosted its full-year profit outlook as smart TV market share continues to grow.

Roku said it lost 9 cents per share over the three months ending in March, well ahead of the Street consensus forecast of 26 cents per share, as net revenue increased by a forecast-busting 51% to $206.7 million as its so-called smart TVs continue to take U.S. market share from rivals such as Samsung Electronics  (SSNLF) .

Looking into 2019, Roku said it sees platform revenues rising to around two-thirds of total sales, which it hopes to steer past $1 billion over the full year. The group is still likely to post a net loss, however, of between $65 million and $75 million.

"Based on strong Q1 results and momentum into Q2, we are raising our 2019 outlook to $1.04 billion in revenue and $470 million in gross profit at the midpoint up 40% and 41% year-over-year respectively compared to roughly 36% year-over-year in our prior outlook," CFO Steve Louden told investors on a conference call late Wednesday.

"We plan to manage the business to roughly EBITDA breakeven in 2019, so some of the Q1 upside is expected to flow through to the full year," he added. "For Q2, our outlook is for year-over-year revenue growth up 42% at the midpoint with Platform revenue representing roughly two-thirds of total revenue."

Roku shares were marked 9.6% higher at the opening bell price and changing hands at $71.68 each, the highest since September 28 and a move that extends the stock's year-to-date advance past 134%.

Roku is guiding for Q2 revenue of $220 million to $225 million; that's above a $218 million consensus and implies 42% annual growth at the range's midpoint. The full-year guidance range has been hiked to $1.03 billion to $1.05 billion (implies 40% growth at the midpoint) from $1 billion to $1.025 billion.

"The company is positioned well as the TV ecosystem evolves to streaming (and its) operating system continues to gain share of connected TV and its ad share dramatically lags its viewership. On the other hand the company faces substantial potential competition and there continues to be a large amount of insider selling," said Loop Capital analyst Alan Gould, who lifted his price target on the stock to $50 but maintained a 'sell' rating.

"It is difficult to justify the valuation on traditional metrics, but we believe Roku will continue to beat quarterly estimates and we have raised our long-term active accounts and revenue projections," he added.