Despite large swings in both directions, stocks overall didn't move very far in 2015. But a few individual companies managed epic rallies even as the overall market ran in place. In fact, shareholders of streaming video giant Netflix (NASDAQ:NFLX), and of e-commerce specialists (NASDAQ:AMZN) and Wayfair (NYSE:W), saw their investments more than double in 2015.

NFLX Chart

NFLX data by YCharts.

Netflix's year of international expansion
Netflix's huge year -- it surged from a $20 billion market capitalization to over $50 billion -- was a product of low expectations meeting phenomenal performance. Heading into 2015, the streamer had just posted its first decrease in year-over-year subscriber growth while projecting another one to follow. Meanwhile, investors were witnessing major costs from its international expansion -- but few of the benefits. Netflix booked $31 million of international losses in the third quarter last year and warned that that figure would leap to $100 million in Q4 (on a base of just 18 million subscribers). Investors weren't pleased.

Image source: Netflix.

But rather than foreshadowing a slowdown, the soft third quarter set the stage for a dramatic uptick in Netflix's business, both at home and internationally. CEO Reed Hastings and his team trounced their subscriber-growth expectations for the fourth quarter even as a big chunk of the subscriber base forked over higher monthly prices for the service. And international growth was so strong that the company accelerated its plan for global domination. Those positive trends carried on through the year as Netflix's subscriber base, attracted by a growing original content portfolio, increased to 69 million members worldwide -- up from 57 million to start 2015.

Amazon's e-commerce and cloud dominance
Like Netflix, Amazon's stock began 2015 having declined in the previous calendar year. In fact, the e-commerce titan's shares fell 22% in 2014 as it booked substantial net losses despite strong revenue gains.

Image source: Amazon.

Yet profits quickly began showing up in Amazon's financial results. In the fourth-quarter results posted in late January, CEO Jeff Bezos announced that the company earned $591 million in operating income -- far above the high range of his team's prior forecast. Then, beginning in the second quarter, Amazon started revealing segment information about its popular cloud services division, which demonstrated huge value in that business. Through the first three quarters of the year, Amazon Web Services grew sales by 70% and nearly quadrupled its profit. Segment operating margin for the segment has spiked to 22% of sales.

Yet the great majority of Amazon's business still comes from online selling. And the good news for investors is that the company is dominating that fast-growing industry. E-commerce has spiked to over 7.4% of all retail from 6.5% a year ago, according to government statistics. Amazon's 20% sales growth is outpacing rivals as its booming Prime membership rolls deepen the company's relationship with millions of customers around the world.

Wayfair's tremendous growth
Having lost 47% in 2014, online retailer Wayfair limped into 2015. Investors weren't happy that despite strong sales growth, the home furnishings seller was bleeding cash and moving further from turning a profit. In its final quarterly report of calendar 2014, Wayfair revealed that over the preceding nine months it had burned through $93 million of cash and lost $75 million in income. Management touted improving metrics like average order value and active customers, but shareholders zeroed in on the worsening cash flow position.

Image source: Wayfair.

In 2015, sales growth accelerated and all of Wayfair's key metrics moved higher. Over the nine months ended in September, revenue surged 66% as the active customer base jumped to 4.6 million buyers from 2.9 million. "We are very pleased to report the third quarter in a row of tremendous growth across the business," CEO Niraj Shah said, while highlighting the fact that Wayfair posted accelerating new customer and repeat customer gains.

But Wall Street is likely most impressed by the fact that Wayfair has achieved positive free cash flow in time for what's expected to be a record holiday shopping season. Consensus estimates peg fourth-quarter sales growth at a scorching 63%.