Here we go again. After a record-setting start to 2019, the stock market is back in turmoil. Don't sweat the reasons why, though -- a breather was long overdue.

In the meantime, there are some high-growth concerns out there worthy of your consideration. Three that our Foolish contributors think are worth your time are Alphabet (GOOG 0.96%) (GOOGL 0.81%), Micron (MU 2.46%), and Teladoc (TDOC -1.04%).

Google doesn't need your worry

Nicholas Rossolillo (Alphabet): In what's becoming a quarterly trend, Google parent Alphabet's stock rallied to new all-time highs only to get knocked down again after reporting on first-quarter 2019. The reason? The search and technology giant's "disappointing" numbers.

After a double-digit tumble, though, this high-growth internet monster is worth another look. It's true that revenue increased 17% during the first quarter -- compared to a 26% year-over-year increase in the first quarter of 2018. However, some of that wide differential had to do with currency exchange rates. Google also alluded to some changes in ad revenue recognition that had an impact, and that Google is not at all concerned with quarterly variability.

Besides, for a company the size of Alphabet, double-digit revenue growth is no small feat. Also, operating income rose 11%. The stock now trades at 29.3 times the last year's worth of earnings, and just 24.4 times the next 12 months' expected earnings. That doesn't make shares cheap, but one could do worse for a high-growth stock.

All the while, the company continues to funnel money into its in-house hardware business, YouTube, and a long list of start-ups ranging from autonomous cars to healthcare data science. Google isn't going anywhere anytime soon, and has plenty of runway to continue growing for many years to come.

A memory-making cash machine

Anders Bylund (Micron Technology): I understand if you're a little scared about owning Micron right now. The memory-chip maker has seen chip prices weaken over the last year, resulting in sharp dips in the company's revenues and free cash flows:

MU Revenue (TTM) Chart

Data by YCharts.

So much for "it's different this time," right?

Right, except that this downturn really is different. The last couple of downward swings in DRAM and NAND memory prices resulted from Samsung flooding the market with an oversupply of cheap chips, driving weaker hands out of business and reducing the cost of building everything from smartphones to memory-equipped home electronics. The Korean company may be the largest memory supplier on the planet, but that operation is still just a minor side gig in Samsung's enormous business operations.

This swing really is different. Prices are falling because Samsung and friends are selling fewer phones these days. There are several potential lifelines on the horizon, including a proliferation of Internet of Things devices and maybe a fresh spark of smartphone interest when 5G networks (and devices capable of connecting to them) start to show up in the wild. But that's still in the future, and trade tensions between Beijing and Washington aren't helping this American company find new customers in the world's largest electronics manufacturing hub, either.

These issues will pass. Without the Sino-American trade conflict, I'm not sure we would have seen a dip in Micron's revenues and cash profits at all -- a leveling off, maybe, but not a plunge.

On top of that, take a second look at the chart above. The long-term trend may be bumpy, but it's unquestionably positive. And we're looking at an absolute cash machine. Micron converted $7.65 billion of its $30 billion top-line sales into free cash flows over the last four quarters, which works out to a 26% cash margin. Does that sound like a company in deep trouble to you?

It doesn't to me, but market makers disagree. Today, Micron shares are trading at the bargain-basement valuation of 3.7 times trailing earnings, or 5.8 times free cash flows. I think that's a big mistake. Expect this stock to get back to its winning long-term ways when the current turbulence fades away. Despite falling 39% from its 52-week highs, we Micron investors have pocketed a 700% return over the last five years. There will be more of that goodness up ahead.

A doctor holding a stethoscope up to a digital image of a person, illustrating telehealth.

Image source: Getty Images.

Time to buy this virtual health leader

Todd Campbell (Teladoc): Patients visit doctor's offices nearly 1 billion times per year in the United States, and while most of those are in-office visits to physical locations, more people are increasingly using their smartphones, tablets, or computers to visit doctors virtually.

At the forefront of this game-changing shift is Teladoc. The company connects patients to doctors for various healthcare concerns, from chronic conditions to the flu. It even provides second opinions from specialists via telehealth solutions. Last quarter, its virtual visits exceeded 1 million for the first time, growing 75% from one year ago. As a result, the company reported total revenue reached $129 million. Even if you x out visits and revenue growth from acquisitions, Teladoc reported organic visit and revenue growth of 29% and 23% in the past year, respectively.

About 82% of its revenue comes from subscriber access fees paid by third parties, including insurers, health systems, and self-insured corporations. These clients pay a fixed amount so members can access virtual visits, because they're considerably cheaper than traditional in-office visits. For instance, a virtual visit is $472 less expensive than an in-office visit, according to Veracity Analytics, an independent healthcare data analytics company. The remaining 18% of Teladoc's revenue comes from per-visit fees.

Currently, Teladoc's solution is available to 27 million people through subscription access relationships, but that's only scratching the surface of this mega-opportunity. In addition to landing new accounts, management estimates that expanding existing relationships could provide access to another 50 million people. Additionally, over 20 million Medicare Advantage members could gain access to telehealth services as soon as 2020. Furthermore, the company's expanding into Europe, opening the door to a population over 500 million.

Despite the massive opportunity, Teladoc's share price has fallen following a short-seller report questioning a referral marketing program for its mental health business last year and the departure of its CFO over allegations of insider trading in December. The referral program, however, only represented about 5% of its new mental health members, and eventually a new CFO will be hired. Given the massive market opportunity and the robust top-line growth, the recent sell-off in shares could make this a great time to add this telehealth stock to growth portfolios.