Shares of Roku (ROKU) - Get Report  were down 11.8% in trading to $68.90 after the stock was downgraded to sell from hold by analysts at Loop Capital, who left the price target unchanged at $45.

The price target represents a 36% downside from the stock's previous closing price. 

The firm said that Roku's valuation is out of control, with analyst Alan Gould saying that he recognizes stocks "can go from expensive to more expensive," adding he can no longer justify his hold rating based on the company's valuation. 

Loop wasn't the only research firm to downgrade Roku, with Macquarie joining in on the bearish tilt, downgrading the stock to neutral from outperform. 

Roku reported revenue of $275.7 million and earnings of 5 cents a share a month ago, topping analysts' expectations. The company also gained in all of its key metrics. Roku's average revenue per user, probably the most important metric for the company, rose 30%, or $4.17, to $17.95 in the quarter.

Those numbers weren't enough to impress analysts at Wedbush, however, who downgraded the stock to neutral from outperform at the time.

"We lowered our long-term EPS estimate on a lower operating margin assumption, given a greater likelihood of higher spending levels than we previously modeled," analyst Michael Pachter said.

A Special Invitation:Do you want to learn more about planning for and living retirement from the nation's top experts, including Ed Slott and Robert Powell, the editor of TheStreet's Retirement Daily? Want to learn how to create tax-efficient income in retirement and how to manage and mitigate all the risks you'll face in retirement? Then sign up to attend TheStreet's Retirement Strategies Symposium on April 6 in New York City. For a limited time, you can attend this extraordinary symposium for $149 - a cost savings of $50 off the general admission price of $199.

You can see the full day's agenda, learn about the guest speakers and sign up HERE for this special event.