A smart strategy to boost your portfolio returns is to emulate what some of the world's best investors are doing. Perhaps no other investor has the legendary status that Warren Buffett carries, so whatever Berkshire Hathaway owns in its massive portfolio can make for a potentially worthy investment candidate. 

As of Dec. 31, the conglomerate headed by the Oracle of Omaha owned a 20% stake in American Express (AXP 0.15%). The credit card company recently reported earnings, just missing Wall Street estimates on the bottom line, but exceeding expectations on the top line, as total revenue (net of interest expense) soared 22% year over year in the first three months of 2022. 

Growth is clearly robust right now, so is it time to buy this top Warren Buffett stock? 

Consumer spending remains resilient 

There's no doubt that AmEx's revenue growth was superb in the most recent quarter. And in fact, this continues the strong momentum it reported for full-year 2022, when total revenue was up 25% versus the prior year. The company's $14.3 billion in Q1 revenue was a record. This is definitely a positive sign amid the ongoing macroeconomic worries on investors' minds. 

However, it wasn't all great news. AmEx's diluted earnings per share (EPS) of $2.40 equaled a 12% year-over-year decline. This was primarily driven by a nearly $1.1 billion provision expense, which included $734 million in write-offs. The provision charge was a stark reversal from the $33 million release in the first quarter of 2022. 

"Going forward, we continue to expect these delinquency and write-off rates to increase over time, but they are likely to remain below pre-pandemic levels in 2023," CFO Jeff Campbell said on the earnings call. 

Now that we've discussed the negative news from the company's latest financial results, let's focus the attention back on the positives. 

The most promising takeaway was that consumer spending remains strong. AmEx's total network volume jumped 14% to $399 billion. The company's travel and entertainment billed business was up 39% year over year -- not much of a surprise given the heightened demand for travel following lockdowns during the worst of the pandemic. Millennial and Gen-Z customers are performing better than any other demographic. And all four of AmEx's segments -- U.S. consumer services, commercial services, international card services, and global merchant and network services -- posted double-digit revenue growth in the quarter. 

Management kept its full-year 2023 guidance intact, still expecting revenue and diluted EPS to grow 16% and 14% at the midpoint, respectively. "Our outlook is based on the blue-chip macroeconomic consensus, which continues to expect slowing growth, though not a significant recession," CEO Stephen Squeri said on the call with analysts. 

No one really knows if there will be a so-called "hard landing" or a "soft" one. But AmEx can weather any storm thanks to its more affluent customer base. "Our customers have been resilient thus far in the face of slower growth and higher inflation economic environment," said Squeri. 

Boosting shareholder returns 

American Express' stock is down 18% from its peak, so it now trades at a price-to-earnings (P/E) multiple of 16.6. This valuation is cheaper than the stock's trailing three-, five-, and 10-year average P/E ratios, which might be compelling enough for some investors to take a closer look. 

If a historically cheap price isn't enough, AmEx recently raised its quarterly dividend by 15%. It carries a yield of 1.5% right now. And the business has long been repurchasing its own stock, reducing the outstanding share count by 14% over the past five years. 

AmEx should be better able to navigate near-term macro headwinds, while also continuing to post stellar growth, as the most recent quarter demonstrated. Therefore, investors looking to put money to work in the financial services sector should consider buying shares.