Billionaires stay billionaires by making smart investment choices. Not every member of the super-wealthy is a stock market wizard, of course, but plenty of them are. Quite a few billionaires either operate or put their money in hedge funds that try to beat market returns.

Financial website WalletHub surveyed quarterly filings for hedge funds to see which stocks these wealthy individuals were buying the most. Three stocks near the top of the list were Amazon (NASDAQ:AMZN), Oracle (NYSE:ORCL), and AbbVie (NYSE:ABBV). Here are the likely reasons why billionaire investors love these stocks.

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Amazon

Big money poured into Amazon in the second quarter of 2017, and I suspect the flow will continue for a while. Amazon stock is up nearly 35% so far this year, trouncing the return of the S&P 500 index. There is no sign yet that the e-commerce giant is losing steam.

We don't have to speculate why some billionaires love Amazon. My colleague Matthew Frankel wrote this summer about how the stock was billionaire Mark Cuban's largest holding because of the company's ability to "disrupt everything." Billionaire investor Stanley Druckenmiller said he loved Amazon "because they're investing in their future." 

Amazon seems to have the Midas touch. The company first entered the book-selling market and now dominates it. It expanded to other consumer products and ranks as the largest online retailer in the world. Amazon is also a leader in cloud computing. The company's next target could be pharmacy, and if Amazon moves forward as expected, the big pharmacy chains should be nervous.

Oracle

Hedge funds shared their love for Oracle earlier this year also. The tech giant stock is up close to 30% year to date and could be up even more if the company had not given weaker-than-expected guidance in September for its fiscal second quarter.

There are several reasons why billionaires have been enthusiastic about Oracle. The company continues to achieve strong earnings growth. Oracle remains the leader in the database software market and has expanded aggressively into the cloud-computing market, offering cloud software-as-a-service, platform-as-a-service, and infrastructure-as-a-service products.

As you might expect, Oracle's cloud push has put it in direct competition with Amazon. Oracle founder Larry Ellison has taunted Amazon Web Services (AWS) in the past, but Oracle still has a long way to go to catch up in cloud revenue. Still, the cloud presents significant opportunities for Oracle to grow. That's likely what quite a few billionaires are counting on.

AbbVie

Billionaires' investments in AbbVie in the second quarter have really paid off. The big pharma stock is up nearly 50% so far in 2017. Nearly all of those gains have come since June.

AbbVie lays claim to the top-selling drug in the world with Humira. Some had been worried that the autoimmune-disease drug could face serious competition from biosimilars in the U.S. However, AbbVie struck a sweet deal with Amgen (NASDAQ:AMGN) that keeps its rival drug Amjevita off the U.S. market until early 2023. 

With Humira in great position to keep rocking along for years to come, AbbVie can enjoy growth from its blockbuster cancer drug Imbruvica. The company also has a rich pipeline with several potential winners, especially experimental cancer drug Rova-T and autoimmune-disease candidate upadacitinib. 

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Should you love them, too?

You shouldn't buy any of these three stocks just because billionaires and hedge funds do so. Still, it's a good idea to understand why they might love these stocks to see if you might love them, too.

If you're afraid of buying stocks with nosebleed valuations, Amazon probably isn't for you. The stock trades at nearly 257 times trailing-12-month earnings and 131 times expected earnings. That lofty level isn't unusual for Amazon, however. If you think, as I do, that Amazon will continue steamrolling everything in its path, the stock could be a great long-term pick.

Oracle, on the other hand, isn't nearly as pricey. The tech stock trades at only 15 times expected earnings. Oracle should grow earnings, but not nearly as quickly as Amazon probably will.

AbbVie is one of my personal favorites. The company has a strong current product lineup with Humira and Imbruvica. I think it will have several more blockbusters on the market in the next few years. The stock trades at a bargain valuation of 14 times expected earnings. On top of all that, AbbVie pays a nice dividend, which currently yields 2.82%. There's a lot to love about all three of these stocks, but there's little not to like about AbbVie.

Keith Speights owns shares of AbbVie. The Motley Fool owns shares of and recommends Amazon. The Motley Fool owns shares of Oracle. The Motley Fool has a disclosure policy.