Investors have many good reasons to love high-growth stocks. A company that's expanding quickly is likely winning market share, for example, which implies potentially enduring competitive advantage. Soaring sales gains often translate into higher earnings, too, as the business benefits from economies of scale and the efficiencies that come from a dominant market position.

With those characteristics in mind, I ran a screen for companies in the S&P 500 index that have improved sales at a rate of at least 25% per year in each of the last three years. Fewer than two dozen stocks met that strict criteria after excluding companies like Charter Communications, which purchased most of their growth through large acquisitions.

So let's take a look at three of the remaining top growth stocks on the list: Netflix (NASDAQ:NFLX), Facebook (NASDAQ:FB), and Arista Networks (NYSE:ANET).

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1. Arista Networks: Cloud software equipment

Arista Networks has been a major force behind, and beneficiary of, the shift toward cloud-based software delivery. Its switching and routing networking equipment has found homes in dozens of leading tech companies, and the financials sprung from that market position are impressive. Revenue rose 31% in the most recent complete fiscal year, and gross profit margin held steady at a blistering 64% of sales. The company's return on invested capital last year was over 100%.

The stock has had a difficult finish to 2019, with shares plunging 24% after Arista predicted a "sudden softening" of growth in its fiscal fourth quarter as a single cloud customer, presumably Microsoft, scales back on its purchases. That slump highlights the variability that shareholders can expect to see with sales growth over short periods. However, investors who believe in the long-term outlook have no shortage of exciting trends to watch, including campus sales, the shift to next-generation switches, and a potential rebound in data center spending at Facebook.

2. Netflix: A streaming tidal wave

Netflix has combined two massive trends, the shift toward internet-delivered entertainment and a clamoring for exclusive content, to produce eye-popping growth over the last few years. Subscriber gains accelerated in each of the five years ending in 2018 as 29 million new members signed up for its services around the world.

That growth streak could end in 2019 thanks to the combination of its already-massive membership base and increasing competition. Yet most investors still expect good things from the streaming video company this year. The even better news is that, while rising monthly prices slowed Netflix's gains in mid-2019, they didn't stall its expansion. Meanwhile, that extra cash will give CEO Reed Hastings and his team significant resources as Netflix battles with new streaming services from Disney and Apple in 2020 and beyond.

3. Facebook: Social media's biggest threat

The scale of Facebook's financial success is hard to overstate. Sales have skyrocketed in the past decade, especially as the company began flooding its news feeds with advertisements in recent years. Revenue (mostly from ad sales) approached $56 billion in 2018 compared to $18 billion back in 2015. Operating income is now $25 billion, up over 20% year over year and five times Facebook's annual haul from just five years ago. 

The social media titan faces its fair share of challenges heading into 2020, including ramped-up capital expenditure spending, pressured advertising rates, and the intense regulatory and societal scrutiny that comes with its dominant influence as a media company and the controller of vast troves of personal data. Yet its impressive engagement metrics -- and its ability to continue growing at scale -- give Facebook more flexibility than its peers as it navigates into a new decade that's likely to include plenty of disruption in the media space.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.