In the stock market, appearances can be deceiving. Securities that seem to be on an unstoppable upward trajectory can sometimes be rising for all the wrong reasons. However, some companies deliver juicy stock market gains for all the right reasons -- because their businesses look to be on a path to long-term success in an industry ripe for growth. 

Take e-commerce giant Amazon (NASDAQ:AMZN) and telehealth specialist Teladoc Health (NYSE:TDOC). Both stocks have easily outpaced the broader market over the past year. What's more, both businesses have what it takes to deliver even more impressive gains in the years to come. All that's required from investors is to keep them stashed in a portfolio for a very long time.

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1. Amazon

Before diving into why Amazon is a no-brainer buy, let's address one concern. Amazon recently announced that its iconic founder Jeff Bezos would step down from the CEO position in the third quarter. He'll be handing the reins to Andy Jassy, CEO of Amazon Web Services (AWS).

Jeff Bezos' decision to step down may turn some investors off; CEO transitions aren't always flawless. But Jassy has proved to be very capable, having led AWS to become the most dominant force in the cloud infrastructure market.

According to the research firm Canalys, AWS held a 32% market share in this segment in the third quarter of 2020. Its closest competitor held a 19% market share. Jassy's track record as the CEO of AWS is one reason why I'm not worried as a shareholder. Also, Jeff Bezos isn't retiring on a beach somewhere -- he'll transition to the role of Executive Chair. There's no doubt his support will be invaluable in helping the company thrive under the leadership of Jassy. 

With that out of the way, Amazon remains an excellent stock to buy, thanks to its leadership in two industries that are still in full growth mode: e-commerce and cloud infrastructure. The company's e-commerce business is laser-focused on serving customers in the best way possible. It has an impressive suite of products and offers such perks as next-day (or overnight) shipping. As of February 2020, the company held a 38.7% market share in e-commerce, according to Statista.

Amazon has already left most of its competitors in the dust. The company's e-commerce business benefits from at least two competitive advantages. First, there's name recognition. As of December 2020, Amazon was one of the top 10 most popular websites in the world (by total visits). Second, there's the network effect -- the value of a service increases as more people use it. Amazon's rich suite of products attracts more customers, which attracts more sellers, and so on. That's on top of the company's cloud infrastructure business.

As a bonus, Amazon has a hand in several other businesses, including streaming video devices, a streaming platform, grocery shopping, and more. The company's leadership in two sectors that are expanding rapidly and its diversified business make it an excellent buy today -- even if you're acquiring less than one whole share of the company via the magic of fractional share purchasing

2. Teladoc Health

Teladoc is a no-brainer buy for one simple reason: The company is one of the leaders in the fast-growing telehealth industry. According to the research firm Grand View Research, this market will expand at a compound annual growth rate (CAGR) of 15.1% through 2027. It isn't hard to see why: Telemedicine offers excellent perks to both patients and healthcare providers.

Patients can have access to some healthcare services (consultations, referrals, prescriptions) practically 24/7 from the comfort of their homes. Meanwhile, doctors can reach a broader range of clients, and because telehealth visits are less time-consuming, they can afford to see more patients per day. Telehealth services also help improve access to quality care in underserved communities and rural areas.

Doctor consulting patient via video conference.

Image source: Getty Images.

Few companies are in a better position than Teladoc to profit from the long-term prospects that telemedicine provides, and here are two reasons why. First, Teladoc benefits from a first-mover advantage. The company was one of the first large-scale providers of telehealth services. Teladoc has successfully built a vast network over the years, consisting of more than 50,000 physicians worldwide who practice in more than 450 medical subspecialties. Newcomers looking to catch up will have to build a similarly impressive ecosystem.

Also, the company's number of visits was growing rapidly even before the pandemic. Between 2016 and 2019, Teladoc's visits increased at a CAGR of more than 60%. In its Q4 earnings report released just this week, Teladoc reported 144.9% year-over-year revenue growth to $338.3 million for the quarter ended Dec. 31.

Second, the company expanded its healthcare offering last year, thanks to its acquisition of Livongo Health. This cash and stock transaction was valued at $18.5 billion and closed on Oct. 30. Livongo specializes in helping those with chronic health conditions, particularly diabetes, manage their illnesses. The company routinely recorded triple-digit top-line growth before the deal with Teladoc. Both Livongo and Teladoc still have a long runway for growth in their respective markets, and the combined entity is even better poised to deliver market-beating returns.

Parking shares of this healthcare stock in your portfolio is a great way to grow your wealth effortlessly. 

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.