Shares of Netflix Inc shares are set to open 24 percent higher after the movie streaming service said it added more than two million U.S. subscribers in the last quarter, with analysts saying a push for exclusive content will boost margins in coming quarters.

Netflix shares have tripled in the past eight months, taking its share price to a sky high 137 times expected earnings, compared with a PE ratio of around 14 for others in the sector.

The shares traded premarket on Tuesday at $215.81, up from $174.36, after first-quarter results on Monday beat analysts' estimates.

Despite the already big jump, at least eight brokerages, including JP Morgan, BMO Capital, Morgan Stanley, Barclays and Oppenheimer & Co, raised their price targets on the stock by as much as $75 to as much as $250.

"Netflix is in an enviable position with its scale and can opportunistically bid on content not available to the company previously." Morgan Stanley analyst DeVitt said in a note.

However some analysts see the shares as overcooked. While upgrading its outlook for the stock, Wedbush Securities gave a 12-month price target of $65 and rated it "underperform."

Netflix now has 29.2 million U.S. customers for its $8-a-month U.S. streaming service, the largest part of its business.

"The solid performance in the March quarter combined with a better-than-expected outlook for the June quarter, aided by the upcoming release of 'Arrested Development: Season 4,' augurs well for the company in 2013 and beyond," BMO Capital Markets Corp analysts said.

"Arrested Development", dropped by network TV but later revived on Netflix, will premiere on May 26 with the entire 15-episode season available to stream online.

"Four billion hours were streamed in the quarter -- highlighting how the company's subscriber base is increasingly using Netflix for a growing share of their viewing trends," BMO said.

As well as boosting subscriber numbers, the push for exclusive content will likely boost margins in line with its premium TV network peers, compounding the effect, DeVitt wrote.

Netflix has been pushing for original shows and its February release of the series "House of Cards", a drama starring Kevin Spacey, generated plenty of buzz just as more and more viewers turn onto Internet video downloading.

"Netflix is racing to ramp up original hours of versatile programming in an effort to build a brand identity with different segments of the market," Susquehanna Financial Group analyst Vasily Karasyov said.

The big run up in Netflix shares has likely hit short sellers but there are still many betting against it.

The short interest position in Netflix for the most recent period was 13.4 percent of shares outstanding, compared with less that 2 percent for blue chip companies such as Google Inc and IBM Corp, according to Thomson Reuters StarMine data.

Short interest position in Netflix peaked in April 2008, with about 38 percent of its outstanding shares being shorted.

Investors who sell securities "short" profit from betting stocks will fall. Short-sellers borrow shares, then sell them, waiting for the stock to fall so they can buy the shares at the lower price.

(Reporting by Supantha Mukherjee and Sayantani Ghosh in Bangalore; Editing by Rodney Joyce)