Since the beginning of the year, Wall Street and investors have been given a reminder that stock market crashes and corrections are perfectly normal occurrences. The double-digit percentage decline the S&P 500 experienced in January marks the 39th correction of at least 10% for the widely followed index since the beginning of 1950.

But where there are crashes and corrections, there's also opportunity. That's because every sizable decline in the S&P 500 has eventually been put in the rearview mirror by a bull market rally. If the broader market were to continue to plunge, the following four companies would be some of the smartest stocks to buy.

A candlestick chart displayed on a computer screen that plunged then bounced back quickly.

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Berkshire Hathaway

In a world where growth stocks have dominated, perhaps no company has more consistently outperformed the broader market for decades than Berkshire Hathaway (BRK.A 0.55%) (BRK.B 0.50%).

Berkshire might not be a household name, but its CEO, billionaire Warren Buffett, certainly is. Since taking the reins in 1965, Buffett has led his company's Class A shares (BRK.A) to an average annual gain of better than 20%. In aggregate, we're talking about a total gain of around 3,800,000% in 57 years.

One of the key reasons the Oracle of Omaha is such a successful investor is due to his company's focus on cyclical businesses. Cyclical companies thrive when the economy is running on all cylinders and struggle when recessions arise. Buffett fully understands that recessions typically last for a few months to a couple of quarters. Comparatively, periods of expansion usually last for years, if not a decade. Warren Buffett is allowing time to be his ally and playing a simple numbers game that works in favor of ultra-long-term investors.

The other not-so-subtle secret to Berkshire Hathaway's outperformance is dividend income. This year, Buffett's company is on pace to collect over $5 billion in payouts, which works out to a yield relative to cost of around 5%. Dividend stocks are almost always profitable and time-tested. This means Buffett and his team have packed Berkshire's portfolio with successful businesses that can navigate whatever the U.S. economy and stock market throw their way.

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Walgreens Boots Alliance

Healthcare stocks are usually a wise place to put your money to work if the market plunges. That's why pharmacy chain and value stock Walgreens Boots Alliance (WBA 0.74%) would be such a smart buy.

No matter how well or poorly the U.S. economy performs, or how high the year-over-year inflation figure rises, people don't get to choose when they get sick or what ailment(s) they develop. This means demand for prescription drugs, medical devices, and healthcare services tends to remain steady in any economic environment.

What specifically makes Walgreens so intriguing is the company's multipoint growth strategy targeting higher margins and a faster organic growth rate. To lift margins, the company has reduced its annual operating expenses by more than $2 billion a full fiscal year ahead of schedule.

Meanwhile, to boost the company's organic growth rate, Walgreens is spending aggressively on two key initiatives. First, it's actively promoting direct-to-consumer sales. Even though the company's brick-and-mortar locations will account for the lion's share of revenue, online sales are an easy way to boost organic growth as consumers shift their buying habits.

Second, Walgreens has partnered with, and invested in, VillageMD to open upwards of 600 co-located, full-service clinics by 2025 in over 30 U.S. markets. These physician-staffed clinics can be used to funnel repeat clients to the company's higher-margin pharmacy.

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Palo Alto Networks

Another exceptionally smart stock to buy if the market plunges is cybersecurity powerhouse and growth stock Palo Alto Networks (PANW 5.33%).

If you're noticing a theme with this list, it's that highly defensive sectors and industries are a smart place to put your money to work when corrections arise. Cybersecurity is a sustained double-digit growth trend which has become a basic necessity for businesses of all sizes that have an online or cloud-based presence. Hackers and robots simply don't care if Wall Street has a rough day.

There are two key reasons Palo Alto makes for such an impressive growth story. To begin with, it's undergoing a business transformation that's emphasizing subscription services. Even though the company continues to sell physical firewall products, subscription services provide better long-term margins and less revenue lumpiness. Over time, a larger percentage of total sales will derive from these higher-margin channels.

Palo Alto's other major growth driver is its many bolt-on acquisitions. Management hasn't been afraid to deploy capital in order to expand its product portfolio or broaden its pool of potential customers. These acquisitions have been pivotal in helping Palo Alto reach new small and medium-sized businesses.

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Bank of America

A fourth and final company that would be one of the smartest stocks to buy if the market plunges is money-center giant Bank of America (BAC 0.92%).

Bank stocks like BofA are highly cyclical. Even though they can occasionally get caught up in the short-term emotions that weigh down stocks, they benefit immensely from the natural expansion of the U.S. and global economy over time. This allows patient investors in large bank stocks to build their wealth steadily over time. Not surprisingly, Bank of America is Warren Buffett's second-largest holding.

What makes Bank of America such a perfect buy at the moment (and if the market continues to fall) is the upcoming shift in the Federal Reserve's monetary policy. With U.S. inflation hitting a 40-year high in January, the nation's central bank has no choice but to aggressively begin raising interest rates. No bank stock is more interest-sensitive than BofA. In its year-end report, the company noted that a 100-basis-point parallel shift in the interest rate yield curve would add an estimated $6.5 billion in net interest income.  In other words, the more inflation becomes an issue, the likelier BofA is to see a big boost to its bottom line.

Also, as I've previously pointed out, Bank of America's digital push is really paying dividends. Over the past three years, it's added 5 million new digital active customers and seen the aggregate number of loan sales completed online or via app jump from 31% to 49%. It's far more cost-effective when customers transact digitally than in person or by phone. As consumers make this digital shift, BofA has consolidated some of its branches and lowered its expenses.