If you've ever wondered why Wall Street pays such close attention to 90-year-old investor who believes in buying and holding stakes in great businesses for a really long time, look no further than Warren Buffett's track record. As CEO of Berkshire Hathaway (NYSE:BRK.A)(NYSE:BRK.B), Buffett has led his company to an average annual return of 20% since taking the helm in 1965. Through 2020, this worked out to an aggregate return of more than 2,800,000%, and it's created over $500 billion in value for Berkshire Hathaway's shareholders.

Like all investors, Buffett isn't infallible. He's going to make mistakes from time to time. But he and his investing team have a knack for locating companies with plain-as-day sustainable competitive advantages. As the summer temperatures heat up, the following three Warren Buffett stocks stand out as screaming buys.

Warren Buffett at his company's annual shareholder meeting.

Berkshire Hathaway CEO Warren Buffett. Image source: The Motley Fool.

Amazon

Was there ever any doubt that Amazon (NASDAQ:AMZN) wouldn't be a screaming buy? Even though it's a stock that was added by Buffett's investing lieutenants (Todd Combs and Ted Weschler) and not the Oracle of Omaha himself, it's nevertheless one of the most attractive holdings in Berkshire Hathaway's portfolio.

As a lot of folks are probably aware, Amazon is the king of the hill when it comes online commerce. This year, the company's marketplace is expected to control roughly $0.40 of every $1 spent online in the United States, according to an April report from eMarketer. The next closest competitor is Walmart, which'll handle about 7% of all U.S. online retail.

Amazon has been able to pivot its incredible online retail success into signing up more than 200 million people worldwide to a Prime membership. While Prime members enjoy free two-day shipping and access to streaming content, the lure for Amazon is that Prime fees generate tens of billions in added revenue that it can use to undercut brick-and-mortar retailers on price and buoy its margins.

What you might not realize about Amazon is that it's overwhelmingly dominant in a second industry, as well. Amazon Web Services (AWS) brought in 32% of global cloud infrastructure spending in the first quarter, per Canalys. Cloud infrastructure is still, arguably, in the early innings of its expansion, and it's a considerably higher margin segment for Amazon than retail or advertising. Thus, AWS is going to send Amazon's operating cash flow to the moon as it grows into a larger percentage of total sales.

For the past 11 years, Wall Street and investors have consistently valued Amazon at a multiple of 23 to 37 times its cash flow. If this range remains intact, a near-tripling in the stock is possible by mid-decade.

A lab technician using a multi-pipette device to place liquid in test tubes.

Image source: Getty Images.

Bristol Myers Squibb

If value investing suits you better, pharmaceutical stock Bristol Myers Squibb (NYSE:BMY) has the makings of a screaming summer buy.

The great thing about healthcare stocks is they're highly defensive. Since we don't get to choose when we get sick or what ailments we develop, there's a consistent demand for healthcare services, drugs, and devices, no matter how well or poorly the U.S. and global economy are performing.

What makes Bristol Myers Squibb such a special company is its organic growth potential and astute dealmaking. To tackle the former, Bristol Myers and Pfizer co-developed the world's leading oral anticoagulant, Eliquis, which looks to be on pace for more than $10 billion in sales this year for Bristol. There's also cancer immunotherapy Opdivo, which is being examined in dozens of ongoing clinical trials. Opdivo is already bringing in about $7 billion annually, and could push higher with continued label expansion opportunities. All told, eight brand-name therapies are on track for at least $1.2 billion in annual sales this year, based on extrapolated Q1 sales totals. 

On the dealmaking front, Bristol Myers Squibb hit a home run when it acquired cancer and immunology drugmaker Celgene in 2019. Celgene's superstar is multiple myeloma drug Revlimid, which brought in $12.1 billion in sales last year and has been growing by a double-digit percentage annually for more than a decade. Longer duration of use, label expansions, improved cancer screening diagnostics, and strong pricing power have all fueled Revlimid's growth. Best of all, it's protected from a large wave of generic competition until the end of January 2026. This means Bristol Myers will be basking in significant cash flow for another 4.5 years.

In a world where valuation premiums are soaring, it seems unjust that a company so profitable should be valued at only 8.5 times Wall Street's consensus earnings for 2022.

An electric vehicle plugged into a charging station.

Image source: Getty Images.

General Motors

Lastly, if you want a screaming summer buy that's near and dear to Warren Buffett's investment philosophy, consider auto stock General Motors (NYSE:GM).

Historically, auto stocks are slow-growing companies that sports high levels of debt and are valued at price-to-earnings multiples that are well below the average S&P 500 company. But General Motors and its peers are the verge of taking advantage of an epic vehicle replacement cycle as consumers and businesses make the shift to electric vehicles (EV).

Initially, General Motors was going to devote $20 billion to EV investment by mid-decade. However, in November, the company upped its expected outlay to $27 billion by 2025, with the ultimate goal of bringing 30 new EVs to market globally. Some of this capital will be used to bring EVs to market earlier than initially planned, as well as to develop GM's battery technology. With IHS Markit forecasting that 10% of all U.S. vehicle sales will be electric by 2025 (up from 1.8% in 2020), a hefty investment in this changing landscape makes sense for GM. 

Equally important are the company's ambitions overseas -- especially in China, the largest auto market in the world. By 2035, the Society of Automotive Engineers of China anticipates that half of all vehicle sales will be some form of alternative energy. Through the first-half of 2021, GM delivered more than 1.5 million vehicles in China.  With an established presence, existing infrastructure, and well-known branding, GM has a real shot at becoming an EV leader in China.

A forward-year price-to-earnings ratio of 8 simply doesn't convey the multi-decade growth opportunity that's on GM's doorstep.

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.