Buckle up and hold on, because 2020 has been quite the ride for Wall Street.

Extreme panic surrounding the coronavirus disease 2019 (COVID-19) pandemic initially sent the widely followed S&P 500 tumbling 34% in less than five weeks, marking the fastest and steepest bear market correction in history. But the quickest rally back to all-time highs in history followed, with the S&P 500 achieving this mark in less than five months.

A cheering businesswoman with a choppy but rising wooden chart in the background.

Image source: Getty Images.

There's no question that volatility can be scary, primarily because we don't know when corrections will occur or how long they'll last. But we do know that long-term investors have a really good chance of coming out ahead.

This is especially true for investors in their 20s. The earlier people put their money to work in the stock market, the more compounding can work in their favor over time. If you factor in dividend reinvestment, the stock market doubles every decade on average. 

Best of all, because investors in their 20s are so young relative to the average U.S. life expectancy of almost 79 years, they're able to take on greater investment risk and buy into fast-growing stocks that have the potential to moonshot higher.

If you're in your 20s and looking to take charge of your financial future, here are three perfect stocks to consider buying right now.

A person inserting their Cash Card into a Square point-of-sale device.

Image source: Square.

Square

Payment processing giant Square (NYSE:SQ) has nearly quadrupled off of its March low, which might give investors some pause. But allow me to offer some perspective here: Visa is up more than 1,000% over the past decade, and it was close to a $40 billion company 10 years ago. At $67 billion in market cap, Square is growing faster than Visa was a decade ago -- and it's just getting started.

Most investors in their 20s are probably most familiar with Square's seller ecosystem. Square provides point-of-sale devices, like credit card chip readers or contactless chip readers, to facilitate merchant transactions. Square then nets a fee based on the dollar value of merchandise that traverses its network. Although COVID-19 has disrupted typical consumer buying habits in 2020, gross payment volume on Square's network exploded from $6.5 billion in 2012 to $106.2 billion last year. For those of you keeping score at home, that's a compound annual growth rate of 49%.

What's interesting about this seller ecosystem is that Square is seeing a greater number of medium and large merchants using its platform to facilitate transactions. Medium and large merchants are defined as having more than $125,000 in annualized GPV. What this means is that Square's merchant fees have considerable upside if the company continues to make inroads with larger businesses.

Equally exciting is Square's peer-to-peer payment platform Cash App. With consumers viewing cash as a carrier of germs during a pandemic, Cash App has been drawing millions of new monthly active users (MAUs). Between December 2017 and June 2020, MAUs grew from 7 million to 30 million, with over 7 million people now using Cash Card, the traditional debit card linked to Cash App accounts.

Cash App allows Square to make money off of merchant transactions, expedited user bank transfers, and even its bitcoin exchange. With the war on cash still in its infancy, Square has all the makings of a fintech stock juggernaut.

A patient conducting a telemedicine visit with a physician using a tablet.

Image source: Getty Images.

Teladoc Health

Another perfect stock for 20-somethings to consider buying and holding for a very long time is telemedicine company Teladoc Health (NYSE:TDOC).

Although the healthcare landscape in this country can be aptly described as a bona fide mess at times, one clear-cut trend you can count on over the next decade and beyond is precision medicine. This refers to services and treatment plans that are personalized for each patient. This is where Teladoc Health comes into play.

Prior to the COVID-19 pandemic, Teladoc was already delivering incredible growth. Annual sales for the company had grown from $20 million in 2013 to $553 million in 2019.  But with hospitals and doctor's offices wanting to keep potential COVID-19-infected patients away, as well as ensure that high-risk persons with chronic diseases avoid unnecessary trips out of their homes, demand for virtual physician and specialist visits has skyrocketed in 2020. In fact, Teladoc could turn in over $1 billion in revenue this year.

The beauty of telemedicine is that it benefits everyone in the healthcare chain. Physicians are less pressed for time, and insurers often face smaller charges for telemedicine visits than in-office ones. And, of course, the patient gets the convenience of speaking with their doctor from the comfort of their home.

What's more, Teladoc is in the process of merging with Livongo Health (NASDAQ:LVGO) in a cash-and-stock deal. Livongo's healthcare solutions aggregate data for patients with chronic illnesses and use artificial intelligence to send tips and nudges to these folks to promote lasting behavioral improvements. Livongo helps chronically ill patients take better care of themselves, which is good for every part of the healthcare industry, including insurers.

With Livongo soon to be under the Teladoc umbrella, this combined company will be an innovative high-growth cash flow powerhouse that young investors will want to own.

A key in a lock surrounded by dozens of digital alphanumeric codes.

Image source: Getty Images.

Okta

Cybersecurity solutions company Okta (NASDAQ:OKTA) is the final stock investors in their 20s should strongly consider adding to their portfolios for the long haul. 

Cybersecurity solutions may not be the fastest-growing industry over the next decade, but it's perhaps the surest-growing one. No matter how poorly the U.S. or global economy is performing, companies of all sizes need security protections in place for their in-office and cloud-based networks. Hackers and robots don't take time off, and neither can businesses when it comes to protecting data.

Okta is an identity verification solutions provider. Okta provides cloud-based software services that use artificial intelligence and machine learning to spot and protect against potential threats. Its solutions might include employing two-factor authentication or other identity verification measures before allowing someone access to enterprise data.

The allure of Okta's business model (aside from providing a basic-need service) is twofold.

First, it's almost entirely subscription-based. Okta's fiscal fourth quarter, ended Jan. 31, featured $158.5 million in subscription revenue out of $167.3 million in total sales. Subscriptions often lead to very high gross margin and low levels of client churn. 

The other aspect of Okta that young investors are bound to love is its growing suite of identity-as-a-service solutions. Okta anticipates its clients will add on new security solutions as they grow. Okta isn't just growing at a rapid pace because it's bringing in new clients; it's also expecting existing customers to spend more over time. This is why Okta's full-year sales have the potential to quadruple by fiscal 2025.

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.