Netflix Inc.'s first-quarter profit climbed 36 percent amid the largest subscriber gains in the online DVD rental service's 10-year history, but a projected slowdown overshadowed the performance.

The tepid forecast provided by the company Monday caused Netflix shares to plummet 14 percent in after-hours trading.

Netflix earned $13.4 million, or 21 cents per share, during the first three months of the year. That compared with net income of $9.9 million, or 14 cents per share, at the same time in 2007.

Revenue rose 7 percent to $326.2 million from $305.3 million.

The earnings matched the average estimate among analysts surveyed by Thomson Financial, but many investors had been betting the company's profit would exceed those expectations.

Netflix ended March with 8.24 million subscribers, a gain of 764,000 customers from the end of 2007. That's the biggest influx of new customers in any quarter since the Los Gatos-based company set up its DVD rental service, which processes requests online and then delivers the discs through the mail.

Management attributed much of the first-quarter surge to a series of rate increases announced in late December by its biggest rival, Blockbuster Inc. The higher prices triggered a backlash that drove more DVD renters to Netflix, which cut its prices last summer.

But Netflix anticipates only 60,000 to 260,000 more customers will sign up during the current quarter ending in June _ typically a challenging period anyway because more people are interested in basking in the warm weather than in watching movies on their couches.

In another worrisome sign, Netflix shaved a penny off the upper end of its full-year guidance to $1.29 per share.

Netflix shares plunged $5.52 in extended trading after rising 76 cents to finish Monday's regular session at $39.32. The company's market value had risen by nearly 50 percent this year before the disappointing second-quarter forecast.

Propelled by more robust growth toward the end of the year, Netflix anticipates entering 2009 with as many as 9.7 million subscribers, up from its previous forecast of 9.5 million customers.

Hoping to defray some of its expenses for stocking its library with the more expensive, high-definition Blu-ray discs, Netflix plans to raise its fees later this year for those rentals by a "modest" amount, Chief Executive Reed Hastings said.

Netflix's most popular rental plans currently range from $13.99 to $16.99 per month.

The rate increases are expected to affect less than 10 percent of Netflix subscribers because relatively few households own Blu-ray DVD players.

Netflix also revealed that it has lined up more partnerships to expand the appeal of a service that lets subscribers stream about 9,000 movies and TV shows over high-speed Internet connections at no additional cost.

Hastings disclosed Monday that three consumer electronics companies have agreed to sell devices designed to make it easier to stream Netflix's digital service on televisions, expanding upon an earlier partnership announced earlier this year LG Electronics.

Hastings didn't identify Netflix's newest partners, but said two of them are well known. The boxes for delivering Netflix's streaming service to television is expected to hit the market during the fourth quarter.

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