2018 has been a topsy-turvy year for the stock market, with an early push to new all-time record highs in January giving way to a correction and continued volatility throughout the remainder of the year so far. Both the Dow and S&P 500 have struggled to post single-digit percentage returns year to date. But for those looking for much stronger performance, some individual stocks have produced much more impressive gains so far this year. Among them are Amazon.com (NASDAQ:AMZN), Netflix (NASDAQ:NFLX), and lululemon athletica (NASDAQ:LULU), and each of these three high-performing companies has a story to tell to explain how its respective share price has climbed so far so fast.

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Amazon.com

Amazon has been a success story for years, and 2018 hasn't slowed the e-commerce giant's momentum one bit. The company spent years ignoring skeptics who argued that despite impressive sales growth, Amazon had not yet demonstrated that it could make a significant profit. Yet recently, Amazon has turned the earnings spigot on, and over the past 12 months, per-share earnings have come in at more than triple the rate they did during the previous period.

Driving those gains are initiatives in every area of Amazon's business. The acquisition of Whole Foods Market has given Amazon a new network of distribution and storage facilities for potential use across its e-commerce operations as well as offering a high-profile showcase for the company's latest innovations. Meanwhile, Amazon's cloud-computing services business continues to be a leader in the fast-growing field, with Amazon Web Services posting more than 45% gains in revenue over the past year. Despite attempts by competitors to eat into its market share, Amazon has resisted any erosion in its fundamental business metrics, and all signs point toward continued success in the foreseeable future.

Paper showing graph of upward-sloping return, with calculator and pen.

Image source: Getty Images.

Netflix

Of these three stocks, Netflix has been the best performer so far in 2018, but some investors are likely disappointed even with the stock's current 74% year-to-date return. That's because as recently as last month, investors were enjoying a much larger triple-digit percentage increase in the stock's price during 2018, and shares are down 16% in just the past month. That loss of momentum is troubling to short-term traders, although long-term shareholders are quite familiar with the streaming service's ups and downs.

The biggest concern about Netflix right now is that the company failed to generate as many new subscribers as it had previously forecast, especially in the U.S. market. Netflix pulled in 5.15 million new users during the second quarter, falling short of its guidance for 6.2 million, and skeptics focused particularly on the slowdown in domestic subscriber growth to 670,000 rather than the 1.2 million that the company had forecast. As competition in the streaming space rises, Netflix will have to keep demonstrating its value proposition to customers. Yet with plenty of international markets left to enter, bullish investors have plenty of ammunition to support their belief that Netflix has more room to run higher.

Lululemon Athletica

Finally, yoga apparel specialist Lululemon Athletic has continued its comeback in 2018. Customers have flooded back despite the company's quality control problems several years ago, and despite the departure of former CEO Laurent Potdevin, Lululemon's business performance has been exemplary. In its most recent quarter, Lululemon posted 25% revenue growth on an 8% rise in comparable-store sales, and its direct-to-consumer sales were higher by more than 60%. Net income more than doubled from year-earlier levels as a result, and the yoga apparel retailer boosted its projections for the full year.

Lululemon has not only gotten back in touch with its traditional customer base but also sought to expand it. Its efforts to attract more men to the brand have seen early success, and purchases in the men's category now account for about a quarter of overall volume. As healthy lifestyles remain in vogue, Lululemon has the status to remain a leader in the field, and ideas like expanding more broadly into different types of clothing could be the next catalysts for growth.

Watch the winners

It's always useful to see which stocks are winning even in turbulent markets. Even as many stocks deal with setbacks, these three companies are still executing well, and shareholders are reaping the rewards as a result.

John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. Dan Caplinger has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Amazon and Netflix. The Motley Fool recommends Lululemon Athletica. The Motley Fool has a disclosure policy.