Netflix saw a bumper number of U.S. subscribers tune in to Web-only TV program "House of Cards" as the second series of the drama was made available on Friday, according to broadband technology firm Procera.
Some 16 percent of Netflix users on one particular Internet service supplied by an unspecified U.S. cable operator watched at least one episode of the show, said Procera.
Procera, which cannot share information on individual clients, said last year the number was 2 percent on a similar sized network, and described the jump in viewers as "massive."
Shares of Netflix hit an all-time high of $439.49 on Thursday, ahead of the show's launch, with the stock surging about 130 percent in the last year. In January the firm posted fourth-quarter earnings that smashed Wall Street's expectations with a fourth straight quarter of accelerating sales growth.
However, hedge fund Blue Ridge and billionaire investor Carl Icahn dumped their shares in Netflix, with Icahn cutting his stake by 2.9 million shares to 2.7 million shares according to a regulatory filing on Friday for the quarter ended Dec. 31.
The network monitored by Procera showed "clear signs of binge watching" as the numbers for each episode show viewers are continuing to watch the series throughout the day on Friday.
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Principal consultant at A.T. Kearney, Kosha Gada said concerns that users would binge on content and then unsubscribe have proved unfounded, as subscribers have surpassed 40 million, meaning the video streaming service now has more users than cable network HBO.
"There was a little bit of concern over whether subscribers would gorge on this content and then sign off but that did not happen. They are retaining people and I think the future is bright for them," she said.
Gada said upside still remains for the share price in terms of domestic and international growth prospects. The company's cost structure and changes to current rules banning broadband providers from prioritizing certain types of internet traffic over others, remain their biggest challenge.
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The rules currently mean cable companies can't hinder access internet video services that compete with the company's own TV services. But they have come under attack by broadband providers and could be revised.
"Acquiring content is increasingly expensive; there is more and more competition from the likes of Amazon, Microsoft and Google getting into this field which drives up the prices of the content," Gada said.
"The net neutrality bill is still circling, if that does become the law of the land they are going to come out of the negative side, because they are a huge portion of all the broadband bandwidth that is being consumed right now. So that will definitely be a huge cost driver for them," she said.
"But the upside in terms of subscriber growth they have should enable them to come out in the black still…but they certainly have their challenges," she added.
—By CNBC's Jenny Cosgrave: Follow her on Twitter @jenny_cosgrave