Momentum stocks have been under heavy selling pressure lately, but that doesn't mean investors should necessarily stay away from these companies. On the contrary, high-growth names such as Netflix (NFLX 4.17%), priceline.com (BKNG 2.05%), and Facebook (META 2.98%) could be profitable buying opportunities for long-term investors willing to tolerate the short-term volatility.

Netflix is no house of cards
Momentum stocks are usually riskier and more volatile, but they tend to offer superior potential for growth in exchange. Besides, volatility can be a source of opportunity for strategic long-term investors looking to purchase extraordinary growth companies on a short-term pullback.

Netflix could be an interesting candidate to consider from that point of view, as the streaming leader is down by more than 25% over the last month. Even if valuation and competitive risks are always a source of concern for investors in Netflix, the company is clearly moving in the right direction on multiple fronts.

Source: Netflix.

Sales during the fourth quarter of 2013 increased by a remarkable 24% versus the same quarter in the prior year, and Netflix is generating rising profitability as sales are outgrowing costs, a crucial factor in the online-streaming business.

Contribution margin in the U.S. increased by 420 basis points to 24.3% during the quarter, and management estimates that it will be able to reach its target contribution margin of 30% in the country by 2015, so profitability should continue rising in the medium term, at least according to management's expectations.

Even after the recent pullback, Netflix is still quite an expensive stock, trading at a forward P/E ratio in the area of 45 times earnings forecasts for 2015. But the company is the undisputed leader in online streaming, and this means exceptional opportunities for growth in the years ahead.

Priceline is traveling higher
Priceline is the leading player in the online travel-services industry, and the company has delivered exceptional gains for investors in the long term, rising by almost 1,200% over the last five years.

Market leadership in Europe via its Bookings.com website is a crucial strategic asset for Priceline considering that the Continent is a major destination for travelers from all around the planet in both good and bad economic times. Bookings.com has built a gigantic network of more than 425,000 hotels and accommodations in that lucrative market as of the end of the fourth quarter of 2013.

Source: Priceline.

The company is truly firing on all cylinders, with gross bookings expanding by 39% in the last quarter of 2013 and sales growing by a remarkable 29.4% versus the prior year. Priceline benefits from a highly profitable business model, the company has an operating margin above 35% of sales, and earnings per share increased by an explosive 30.7% during the last quarter.

The stock has fallen by nearly 15% in the last month, and this makes Priceline attractively valued for such an exciting growth name. The company is trading at a forward P/E ratio around 18, a compelling valuation when considering the company's financial performance and long-term potential for growth.

Should you accept the friend request from Facebook?
Facebook has fallen by nearly 20% over the last month, and the stock is not particularly cheap with a forward P/E ratio near 34, but the company has made remarkable advancements in the key area of mobile monetization over the last several quarters.

Sales during the fourth quarter of 2013 jumped by 63% versus the same period in the prior year, reaching $2.59 billion. Revenues from advertising increased by 76% to $2.34 billion, and mobile advertising sales represented a big 53% of total advertising revenues during the quarter, a considerable increase versus 23% in the fourth quarter of 2012.

Source: Facebook.

Operating margin came in at 44% of sales, a remarkable jump versus 33% of revenues in the fourth quarter of 2012, and adjusted earnings per share grew by an explosive 82% year over year.

Big acquisitions such as WhatsApp and Oculus are showing that Zuckerberg and his team are not afraid of making bold moves with the company's money, and that is a considerable source of risk for investors in Facebook. On the other hand, the company continues strengthening its competitive position in a business offering extraordinary potential for growth.

Bottom line
Momentum can be a double-edged sword: Companies that usually rise more steeply in good times tend to be more volatile to the downside, too. But that's no reason to panic; short-term volatility can create compelling opportunities for long-term investors, and companies such as Netflix, Facebook, and Priceline are positioned to continue generating exceptional growth rates for investors over years to come.