We can say with near certainty that, at some point, the S&P 500 will pick up steam and soar beyond its previous record high, set on Jan. 3, 2022. While the U.S. economy is currently in a tightening cycle as the Federal Reserve holds interest rates at the highest levels they've been at in more than two decades, investors appear to have their eyes on the horizon; the S&P 500 has risen more than 14% this year as the market is beginning to bake in a potential economic reacceleration.

At some point, the Fed will no longer raise rates. Even more, interest rates will eventually begin coming down. Once it becomes clear that inflation has been tamed and the Federal Reserve wraps up its hawkish tightening, the U.S. economy could boom, and stocks could soar. But investors don't want to wait for the good news to enter the market. Instead, they should consider owning stocks before we're in the clear. After all, since the market is forward-looking, investors will likely start pricing in an economic boom before it occurs. Investors who remain on the sidelines risk missing potentially momentous gains.

But what, exactly, is a good way to profit from a potential economic acceleration? One idea is one of Warren Buffett's largest and longest stock holdings: American Express (AXP -0.62%). Warren Buffett's holding company, Berkshire Hathaway's (BRK.B -0.69%) (BRK.A -0.76%) has a stake in the company valued at about $24 billion, or over 20% of the integrated payments company's shares outstanding. Here's why investors may want to follow Buffett's lead and invest in this wealth compounder.

Multiple powerful growth drivers

A close look at American Express, which boasts one of the major credit card brands in the U.S., shows that there's a lot to like.

First, there's the company's premium customer base; the average customer spend per American Express card is three times the average spend on cards at other networks. This premium customer is likely more resilient than the average lower-spending customers that other networks attract, positioning the company well for both continued macroeconomic uncertainty or an economic boom.

In addition, American Express also dominates the small business space, boasting three times as many business cards as the next largest competitor. On the same token, the company boasts a 45% share of U.S. small business card payment volume.

Also, unlike Visa and Mastercard, American Express isn't just the payments processor for its cards but also the lender. This integrated model gives American Express efficiency advantages since it controls the entire value chain behind every credit card.

Finally, the company boasts a conservative balance sheet. It's management's practice to maintain a Common Equity Tier 1 ratio of 10% to 11%, well beyond the regulatory minimum of 7% and likely materially in excess of what any updated regulations would require.

We haven't even expanded on some of the other unique factors of American Express' business, including its high customer retention levels or its fee-based membership model.

All of these facets of American Express' business combine to make the company an attractive way to bet on a proven and resilient business benefiting from the expansion of upper-income households, the growing spending of many of the world's wealthiest people, continued global adoption of credit cards, and expected market share gains with younger generations.

A growth stock without a growth valuation

"All of this sounds great. But show me the growth," some readers might be thinking.

Fortunately, this is actually the easy part. American Express' revenue rose 12% year over year in the company's most recent quarter, despite an incredibly tough year-over-year comparison; revenue in the year-ago period rose 31% year over year. 

Given the company's improving appeal to younger customers, growing spending from existing customers, steadily rising annual membership fees on its cards, and global expansion, management confidently reiterated its aggressive long-term growth aspirations in its second-quarter earnings call. The company expects annual revenue growth at rates in excess of 10% and earnings-per-share growth rates in the mid-teens annually in 2024 and beyond.

Given the company's long history of success and American Express' outstanding execution in recent years, investors may want to take the company's growth aspirations seriously. With a price-to-earnings ratio of just 16 at the time of this writing, the market's fragile sentiment about the economy and the financial sector, in general, seems to be causing investors to miss this big picture -- particularly regarding American Express' shares.

This growth stock deserves a much higher valuation. While there's no way to know where the bottom is to the stock's pullback this month, investors who buy shares today likely won't regret it five years from now.