The stock market has been chock-full of volatility in recent days. While concerns about another steep downturn abound, avid long-term investors can still seize upon ripe investment opportunities to drive sustainable, meaningful portfolio growth.

Today, we're going to take a look at two such companies that have not only proven to be unstoppable growth stocks in the worst of the pandemic, but can also continue to act as long-term catalysts for wealth creation regardless of what the market does in the coming months. And if the market does plunge into bear territory again, this could create a prime opportunity for investors to buy shares of these high-caliber stocks at a considerable bargain.

Let's dive right in.

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Image source: Getty Images.

1. Teladoc

In 2020, Teladoc (TDOC -23.67%) reported 98% revenue growth and a 156% increase in visits conducted on its platform. The telemedicine company's revenues then surged by triple digits (151%) in the first quarter of 2021, while the number of visits on its platform jumped 56% year over year. Management is forecasting that Teladoc will increase its 2021 revenues by as much as 85% from 2020 and deliver adjusted EBITDA (earnings before interest, taxes, depreciation, and amortization) between $255 million and $275 million. Teladoc reported adjusted EBITDA of $127 million in 2020.

Although shares of Teladoc are trading more than 20% lower than one year ago, the stock's long-term prospects as a growth investment are just as strong as ever.

It's important to remember that Teladoc is the foremost presence in the rapidly expanding field of telemedicine, an industry that has accelerated its growth at an exponential rate during the pandemic and is expected to continue doing so in the years ahead. According to a February 2021 report by Grand View Research, the telemedicine market hit a worldwide valuation just shy of $56 billion in 2020 and is projected to realize a compound annual growth rate (CAGR) of more than 22% between 2021 and 2028.

The report cites "rising provider adoption of telemedicine, rising consumer demand and patient acceptance, and enhanced quality of care" as key catalysts behind this notable rate of projected and continued growth in the virtual healthcare arena.

Teladoc's platform connects patients and providers across the complete scope of healthcare needs. From virtual primary care visits to mental health services to consultations about more specialized health concerns, Teladoc's platform makes getting quality healthcare more easily accessible and more affordable to a wider range of consumers while enabling medical providers to reach broader swaths of the patient population.

The indispensability of the services that Teladoc provides goes hand in hand with the increasingly digital age in which we live, and the considerable long-term growth trajectory of the global telemedicine industry paints a picture of an equally bright future for this healthcare stock

2. Apple

Veteran FAANG stock Apple (AAPL 0.42%) continues to prove its mettle as a stalwart investment for all market conditions. While shares of the company have experienced some volatility in recent weeks, this isn't surprising given the current state of the market and the usual cyclical fluctuations.

Apple delivers rock-solid financial performance quarter after quarter with its top-selling lineup of new and existing products. In Apple's fiscal 2020 (ended Sept. 26), the company's net sales and net income increased by 6% and 4%, respectively. Apple reported net sales spikes in four out of its five business segments in fiscal 2020, with the exception being a slight decline in iPhone sales during the 12-month period. The fourth quarter also marked a period of record growth for Apple, propelled by substantial sales increases in its Mac and Services business segments.

Apple has already kicked off its fiscal 2021 on a very high note, reporting record revenues in both the first and second quarters (ended Dec. 26 and March 27). The company's first-quarter revenues of $111 billion represented a 21% increase from the year-ago period, and its second-quarter revenues shot up 54% year over year to just shy of $90 billion. 

Along with revenue from the Mac, Wearables, and Services divisions, Apple's iPhone segment was a notable catalyst for balance-sheet growth in both quarters. Net sales in this segment alone showed year-over-year increases of 17% in the first quarter and a whopping 66% in the second quarter.

Commenting on Apple's second-quarter results, CFO Luca Maestri said, "We are proud of our March quarter performance, which included revenue records in each of our geographic segments and strong double-digit growth in each of our product categories, driving our installed base of active devices to an all-time high." Maestri noted, "These results allowed us to generate operating cash flow of $24 billion and return nearly $23 billion to shareholders during the quarter."

Although Apple's dividend currently yields less than 1%, about half the S&P 500's average of 2%, the company's impressive cash flow generation and storied commitment to meeting its shareholder obligations make the stock a compelling pick on this front. Coupled with Apple's ever-expanding portfolio of electronics, software, and services, all of which face tremendous catalysts for long-term growth, the stock continues to be an investment you can buy and hold for a lifetime.