Last year, so-called stay-at-home stocks took off even as the market dropped due to the COVID-19 pandemic. But many of these same companies have struggled since the beginning of this year. Case in point: Shares of telehealth specialist Teladoc Health (NYSE:TDOC) and those of tech giant Amazon (NASDAQ:AMZN) have both underperformed since 2021 started.

Could this below-average performance be a great opportunity for investors to purchase shares of both Teladoc and Amazon? Given the prospects of both companies, I believe the answer to that question is a resounding yes. Let's dig deeper into their respective businesses and see why it is worth investing in both Teladoc and Amazon.

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1. Teladoc 

Here's one thing we all need regardless of economic conditions: healthcare. That's why almost any company that makes medical services more accessible at a fraction of the price will be successful. That's why Teladoc is such a great option to consider. As one of the leaders in the provision of virtual care services -- which offer a convenient, time-saving, and cheaper method of conducting consultations with physicians -- Teladoc has an amazing opportunity to ride this long-term trend. 

The coronavirus outbreak accelerated the adoption of telemedicine, and patients will want access to these services even after the pandemic subsides. Last year, Doctor.com conducted a poll of more than 1,800 adults, of whom 83% said they would continue to use telemedicine even after the pandemic is over. And while estimates of the growth of the industry vary, the numbers tend to look very favorable. According to a report by the research firm Grand View Research, this market will be worth $298.9 billion in 2028, up from $55.9 billion in 2020.

Here are just two potential growth areas Teladoc can exploit in the coming decade. First, the company can seek greater adoption among employers who offer telehealth as part of their employees' insurance plans. Teladoc already has over 50% of the Fortune 500 companies on its client list.

Given the increasing popularity of these services, more companies will consider including telemedicine in their employees' health plans. But why would these institutions turn to Teladoc as opposed to one of its competitors? This brings us to potential growth area No. 2: The company boasts a growing and varied suite of virtual care offerings. Teladoc offers services in specialty care areas such as diabetes, hypertension, and mental health.

During the company's fourth-quarter 2020 earnings conference call, CFO Mala Murthy said the following: "Growth in specialty visits has been particularly strong, led by growth in behavioral health, which experienced visit growth of over 500% in 2020 as the growth in visits accelerated throughout the course of the year." For context, Teladoc's total visits increased by 130% in 2020 compared to 2019.

An expanding network of services and an increasing client list within an industry that's ripe for growth will help push this healthcare stock to greater heights, despite its recent struggles. 

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2. Amazon 

Amazon has shattered average stock market returns over the past 20 years, and the company is currently valued at an impressive market cap of $1.65 trillion. Does the tech giant still have room to grow? I believe it does, and here's why. Though Amazon originally started as an online bookstore, today the company offers hundreds of products on its customer-centric e-commerce platform.

Amazon's online marketplace comes with benefits that are likely to attract an ever-growing clientele, most notably its one-day shipping options, among many others. That's why Amazon remains one of the leading e-commerce companies in the world. According to Grand View Research, this sector is poised to continue expanding at a compound annual growth rate (CAGR) of 14.7% through 2027, and the tech company is well positioned to profit. 

Amazon's platform is also a dream come true for advertisers thanks to its popularity, and the company will continue to generate growing advertising revenue. Beyond e-commerce, Amazon also manufactures and sells electronic tablets, owns a streaming service, and it acquired Whole Foods -- a grocery store chain -- back in 2017.

The company has the means to launch ventures into even more industries thanks to its big pile of cash: Amazon generated $21.8 billion in free cash flow over the trailing 12-month period. The company is certain to make a bigger push within the healthcare field thanks to its Amazon Care in the coming years.

Last but not least, Amazon is the biggest player in the cloud computing industry -- another rapidly growing market -- thanks to its Amazon Web Services (AWS). In the fourth quarter of 2020, the company had a 32% market share in this industry, well ahead of the runner-up Microsoft's Azure, which had a 20% market share.

Thanks to its leadership position in two growing industries coupled with a diversified business, Amazon still looks like it can deliver above-average returns for many years to come.

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.