You might get motion sickness watching the stock market's wild gyrations. But despite the crazy volatility, there are a lot of great stocks to buy if you're a long-term investor.

I personally invested in three of those great stocks last week. Was I worried that they might fall even more over the next few months? Did my fingers tremble as I pressed the button to buy? No and no. I'm confident about the long-term prospects for all three businesses. Here are the stocks I bought last week -- and why I plan to buy even more shares of them in the near future. 

Nest with three eggs painted to look like hundred dollar bills

Image source: Getty Images.

1. Amazon.com

Amazon.com (NASDAQ:AMZN) is faring better than most stocks are during the coronavirus market crash. That makes sense to me, considering the company's e-commerce and cloud businesses should perform well even with consumers cooped up in their houses.

Actually, I think the COVID-19 pandemic could boost Amazon's business over the long run. E-commerce was already booming, but even more people could appreciate the convenience that it offers during this period of quarantines and shelter-in-place orders -- especially with the company's AmazonFresh grocery delivery service.

My hunch is that Amazon Prime subscriptions are also surging. The free delivery is a big draw, but with so many people at home the video streaming service that's included with Amazon Prime is also a key attraction.

But I'd like Amazon even if it didn't enjoy a tailwind from the coronavirus crisis. I fully expect the company will become a major player in the pharmacy business. I think it will continue to be a top leader in artificial intelligence (AI). And I won't be surprised if Amazon's home robots that are reportedly on the way soon gain widespread adoption. 

The bottom line for me is that Amazon has a fantastic moat and plenty of ways to grow in the future. That's the kind of stock to buy anytime, but especially when it's available at a discounted price.

2. Mastercard

Mastercard (NYSE:MA) has been hit hard by the COVID-19 outbreak. With consumers spending less, the payment processing giant has already lowered its first-quarter outlook and withdrawn its full-year 2020 guidance.

None of this bothers me, though, because the negative impact from the coronavirus on Mastercard's business will only be temporary. Mastercard's long-term prospects continue to look really strong.

The same e-commerce trend that will help Amazon also benefits Mastercard. Customers that buy online are a lot more likely to use a credit card than those who purchase products at a brick-and-mortar store. But what if they use a digital payment method like those offered by PayPal and Square? There's still a good chance that Mastercard will make money because in many cases those digital payments are linked to consumers' credit cards.

Mastercard is basically part of a duopoly, along with Visa, in the payment processing industry. The barriers to entry in this business are huge. Mastercard's platform becomes even more valuable with higher numbers of users -- a tremendous network effect.

These competitive advantages, combined with the great growth prospects stemming from the continued rise of e-commerce and the shift from cash to digital payments, make Mastercard one of the most attractive stocks on the market, in my view. I'll absolutely be adding to my position in this stock.

3. Microsoft

Like Amazon, Microsoft (NASDAQ:MSFT) stock has weathered the COVID-19 storm better than most. The technology leader's Teams real-time collaborative software has especially gained momentum, with more than double the number of users than it had just a few months ago.

Probably my favorite thing about Microsoft right now is its Azure cloud infrastructure business. Azure is growing even faster than Amazon Web Services. I expect that it will fuel significant growth for Microsoft for years to come. 

I'm not a big gamer, but I also like Microsoft's key position in the fast-growing market. The company's Xbox is enormously popular. A next-generation version of Xbox is on the way that Microsoft claims will be the most powerful console ever and that could drive even more sales growth for the company.

Many big companies and small companies alike tend to be "Microsoft shops." Their IT staff are familiar with Microsoft and aren't likely to switch to other products. I think this gives the company a solid moat, while it has growth opportunities in multiple arenas.

Microsoft was a laggard for a long time. That's changed. It's now a hot growth stock that I think will keep on growing.