SAN FRANCISCO — Netflix is enthralling viewers and investors alike as popular original programming such as “House of Cards” lures subscribers at a quickening pace.

Netflix said Wednesday that it gained 4.9 million subscribers in the first three months of the year, more than any other quarter since the video streaming service’s debut eight years ago. About 2.3 million of the new customers were in the U.S., where Netflix’s subscriber count surpassed 40 million for the first time.

The results were far better than management had anticipated. Netflix had been hoping to add about 4 million subscribers in the quarter, which typically is a busy period because winter weather keeps people indoors more frequently. The company is on such a roll that it now expects to add another 2.5 million subscribers during the April-June quarter, traditionally its slowest time of year.

Netflix’s big quarter coincided with the return of “House of Cards,” an Emmy-winning political drama starring Kevin Spacey as a conniving U.S. president. The February release of the series’ third season attracted more viewers than ever, Netflix said, though the company didn’t provide specific audience sizes.

Two other made-for-Netflix series, “The Unbreakable Kimmy Schmidt” and “Bloodline,” also helped the company retain existing subscribers and attract new customers curious about the programs. Netflix plans to spend more money advertising its expanding lineup of original programs while also using its recommendation system to pinpoint more subscribers likely to enjoy certain series that are unavailable on other services.

“In this particular quarter, we had some amazing content,” Netflix CEO Reed Hastings said in a video review of the company’s first-quarter financial results. “All of that compounded to push us forward.”

Original programming is becoming increasingly important for Netflix as it faces more competition from other services, including an Internet-only option that pay-TV channel HBO recently started selling this month for $15 per month. That price is well above Netflix’s streaming service, which typically costs $9 per month.

Hastings said HBO’s price underscores what a bargain Netflix is.

All told, Netflix ended March with 62.3 million subscribers in more than 50 countries. They watched more than 10 billion hours of video collectively during the first three months of the year – an average of nearly two hours a day per subscriber.

Despite the growth, Netflix missed analysts’ earnings targets as the company invested in an ongoing international expansion. Netflix also was hurt by the stronger dollar.

Its stock soared $53.04, or 11 percent, to $528.50 in extended trading after the data came out.