Identifying great companies that are disrupting their respective markets is a great way to boost you portfolio's long-term returns, but that can be easier said than done. Our Motley Fool contributors scoured the stock market, hunting for growth-oriented stocks with catalysts that could make them top performers. Although no one knows where these stocks will trade tomorrow, next month, or next year, Fitbit (NYSE:FIT), Ariad Pharmaceuticals (NASDAQ: ARIA), and Trex Company Inc. (NYSE:TREX) might have what it takes to double. Read on to see if these three growth stocks are right for your portfolio.

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Be greedy when others are fearful?

Evan Niu, CFA (Fitbit): Fitness tracker maker Fitbit (NYSE:FIT) has been on a wild ride in its short life as a publicly traded company. Shares now trade at all-time lows following third-quarter earnings that included awful guidance for the fourth quarter. The company is facing some operational challenges as it heads into the busy holiday shopping season, and it fears it might miss out on $50 million of unfilled demand due to supply constraints for its Flex 2 device. Meanwhile, the broader wearables market is already starting to slow, particularly for basic wearables like Fitbit's products.

Beyond fourth-quarter guidance, which only forecasts revenue growth of 2% to 5%, Fitbit still appears to be in growth mode. Sales grew 23% last quarter, and full-year 2016 revenue should still increase by about 25% to 26%. Investors will have to wait to see what the company's guidance for 2017 sales looks like, but it has the potential to recover. With shares trading near $8 and pessimism prevailing, it wouldn't take a lot for shares to double from their current levels -- shares had traded as high as $17 just two months ago.

To be clear, Fitbit has its fair share of strategic challenges going forward. Smartwatches that run third-party apps are a major threat to basic fitness trackers, and Fitbit needs to prove that it can launch a compelling product in this category as competition continues to intensify. There is no shortage of risks. I don't necessarily believe that shares will double, but they certainly could if Fitbit can begin executing on a turnaround and addressing some of its operational setbacks.

Todd Campbell (Ariad Pharmaceuticals): One growth stock I'm keeping an eye on is Ariad Pharmaceuticals. Sales of the company's leukemia treatment Iclusig have grown by a compound annual rate of 77% in the past three years, and Iclusig revenue could continue to climb as oncologists get increasingly comfortable using it. Iclusig's addressable market is between 1,000 and 2,000 patients today, but trials that could expand its use earlier into chronic myeloid leukemia could eventually expand that market to 4,000 patients. If those studies pan out, then Iclusig's sales could meaningfully climb beyond their current annualized run rate of $134 million in the third quarter.

Another reason for optimism is the pending Food and Drug Administration decision on Ariad Pharmaceuticals' brigatinib. Brigatinib is under review for use in amenable lung cancer patients who are resistant to Xalkori. A decision is expected in April, and if brigatinib is approved, it could add another nine-figure drug to Ariad Pharmaceuticals' lineup. Initially, Ariad Pharmaceuticals pegs brigatinib's addressable market at 4,000 patients, but studies that are evaluating it head-to-head against Xalkori could as much as double that number. 

Currently, Ariad Pharmaceuticals' high spending means it's still losing money. However, if Iclusig's sales grow and brigatinib begins generating meaningful sales, that could change. Industry analysts think Ariad Pharmaceuticals' sales could eclipse $300 million in fiscal 2018, and if they do, then this company could be worth considerably more than it is today. To put the longer-term opportunity for brigatinib in perspective, the global market for drugs that work like Xalkori is worth about $800 million today and projected to grow toward $2 billion in the coming years. In Q3, Xalkori's sales alone were up 14% year over year to $140 million.

Admittedly, biotech stocks like this are inherently risky. Trials can fail, and stocks can take a bludgeoning when they do. Nevertheless, Ariad Pharmaceuticals' Iclusig offers some insulation against a brigatinib disappointment, and if brigatinib does make it to market, then I think this company will look even more intriguing.

A market leader with a huge growth opportunity 

Jason Hall (Trex Company Inc.): It may be hard to imagine that a company with more than 40% share of a relatively mature market still has room for rapid growth, but I'm convinced that Trex Company Inc. does. Trex is almost a hidden opportunity: After all, it operates in the outdoor decking business, a relatively boring industry that's only growing by about 2% to 3% per year and is also highly exposed to the cyclical ups and downs of the housing industry and the overall economy. 

But Trex is disrupting the industry with wood-alternative decking that's composed of 95% recycled material and doesn't require the annual maintenance and upkeep of a traditional wood deck. And while there are plenty of competitors in the same space, Trex is the gorilla, regularly winning awards for its product quality and growing sales far faster than its competitors. At last count, it commanded over 41% of wood-alternative decking sales, up from around 35% only a few years ago.

Trex has much bigger goals than simply growing market share in its own segment, however. At last count, Trex's market share of total decking volume, which includes sales of wood and wood-alternative products, was only about 6%. In other words, there's another 94% of decking material sold each year that's not made by Trex -- a significant opportunity to grow sales in years to come. And incremental sales will deliver huge profit growth for Trex. So far in 2016, sales are up 9%, while net income is up 34%, largely due to better operating leverage. 

And Trex stock isn't particularly expensive for a company with such growth prospects, trading at a trailing price-to-earnings multiple of around 33. Given a steady housing market and economy, Trex's ability to continue growing market share should lead to big profit growth, driving the share price up along with it.

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.