Updated 6 p.m. ET

Netflix (NFLX) got hammered in trading Wednesday, with shares falling 25% after the company said it may not meet its 2012 subscriber goals.

In his quarterly letter to investors, CEO Reed Hastings said the company's goal of adding 7 million U.S. customers will be "challenging" if the company can't nail the upper end of its growth estimates in the current quarter. Wall Street already thought that number would be tough to hit, especially after Netflix gained only about 2.25 million U.S. subscribers in the first half of the year.

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The Summer Olympics will make it harder to get new customers, Hastings added.

His cautionary comments came after Netflix reported a second quarter that wasn't that bad. The company returned from a loss in the first quarter to a profit of $6.16 million, or 11 cents a share, a far better showing than the 5 cents a share analysts were looking for. Revenue rose 13% to $889.2 million -- about what analysts had expected.

The company said it would likely be profitable again in the third quarter but could head back into the red in the fourth quarter as it launches in a new, unnamed international market.

Netflix said it added about 530,000 streaming subscribers in the U.S. in the quarter to nearly 24 million. It added nearly the same number internationally, to 3.6 million total. But its by-mail DVD rental business lost 850,000 in the U.S. to 9.2 million.

In all, Netflix's customer base totaled 30.1 million subscribers worldwide.

Netflix said its goal for the current quarter is 1 million to 1.8 million domestic new subscribers. "If we finish Q3 in the high end of that range, we would remain on track for 7 million domestic net additions for the year; otherwise it would be challenging to achieve that goal by year end," Hastings wrote in his investor letter.

Netflix shares closed down 25% to $60.28 Wednesday. Shares have been extremely volatile over the past year, starting in September, when the company increased prices by as much as 60% for some customers. It briefly tried to separate its DVD business from the rest of the company and rename it Qwikster. The change angered customers and badly damaged the company's brand. Hastings estimated it would take three years for the brand to recover.

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