Nu Holdings Already Has More Customers Than Most U.S. Banks. The Real Question Is: What Can It Can Earn From Each One?

Investors might think that the world of financial services is generally a boring area to park capital for growth. But Nu Holdings (NYSE: NU) proves that this perspective is wrong.

The Latin American fintech stock, which has climbed 93% in the past three years (as of May 27), has expanded rapidly. As of March 31, the online bank counted 135 million customers, up 71% from exactly three years ago. This figure is more than what most U.S. banks currently have.

What matters most, though, is not necessarily the total customer count. Investors should care what Nu earns from each one.

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A look at the unit economics

Absolute growth metrics get a lot of attention. Monetization is crucial as well. During the first quarter of 2026, Nu reported average revenue per active customer (ARPAC) of $15.90. This number has steadily risen, and it's up 23% year over year on a currency-neutral basis.

On the other side of the equation, it cost Nu just $1 to serve each of these customers in the first quarter. That's a wide gap when compared to its ARPAC. And it certainly helps to explain why the company was able to post a 16.4% net profit margin in the latest quarter. This was also supported by credit quality that remains within historical levels.

Nu's biggest market, without a doubt, is Brazil, where 83% of its customers are active on a monthly basis. The fintech is still in the early innings in Mexico, but success is notable. On the first-quarter earnings call, CEO David Velez said: "In four years, our customer base there has grown from just over 2 million to 15 million today, roughly seven times larger. ARPAC has nearly doubled, even as we have onboarded millions of newer, less mature customers."

The business is also approaching 5 million customers in Colombia. As Nu further penetrates newer markets, they should start to have a bigger impact on the financials.

Pay attention to growth and monetization

A huge customer base puts Nu in a very favorable position, especially in the financial services industry. That's because it raises cross-selling opportunities, because people generally need a variety of financial services over time.

The combination of both variables -- customer growth and monetization -- is what can drive the best outcome for Nu, which is profitable expansion. The last thing that investors want to see from this business is for customer additions to materially weaken. And if it starts to post softer monetization rates, it might also be a reason to worry.

Right now, though, investors should remain bullish. This company is operating at a high level.

Neil Patel has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends Nu Holdings. The Motley Fool has a disclosure policy.