The J Curve Insider: How WhatsApp Took Over Brazil’s Economy—And What’s Next

In Brazil, WhatsApp is not just a messaging app—it’s the backbone of how Brazilians do business. More transactions now happen through WhatsApp than traditional e-commerce. Banks, retailers, and even governments run their core operations inside the platform, reshaping the way millions interact with businesses.

And behind the scenes, driving this shift, is Guilherme Horn—a fintech pioneer who built Agora (acquired for $500M by Bradesco) when only 15,000 Brazilians invested in the stock market, launched Orama (Brazil’s first cloud-based bank) before anyone trusted the cloud, and now leads WhatsApp’s Strategic Markets. For decades, people assumed business needed apps and websites. WhatsApp is proving them wrong. Just like mobile replaced desktops, Conversational Commerce (C-Commerce) is replacing traditional online shopping, banking, and customer service. To break it all down, I sat down with Guilherme Horn, fintech founder turned WhatsApp executive. Guilherme has strong opinions on why crisis is the best time to build, how WhatsApp is becoming the OS of Brazil’s economy, and why Open Finance + AI is the most overlooked fintech opportunity right now. Let’s get to it.

ECONOMIC ENGINE.

Olga Maslikhova: Guilherme, let’s start with the big picture. In the U.S., WhatsApp is just a messaging app. But in Brazil, it’s how businesses run. Why do you think Brazil has embraced WhatsApp for business so much more than the U.S.?
Guilherme Horn: Two words: culture and necessity. Brazilians are hyper-conversational. In the U.S., If you walk into a store, you grab what you need and check out. In Brazil, someone asks how they can help you before you even finish looking. That behavior naturally translated to WhatsApp. But more importantly, many businesses never built traditional online infrastructure. Unlike in the U.S., where companies invested heavily in websites and apps, Brazilian businesses skipped straight to chat.

So if you’re a small business, would you rather:

✓ Build a website, pay for ads, and hope customers visit?

✓ Or sell directly on WhatsApp, where your customers already are?

It’s not even a choice. More transactions now happen on WhatsApp than on traditional e-commerce platforms.

OM: And now we’re seeing the rise of Conversational Commerce (C-Commerce). How big is this shift?
GH: It’s massive. Founders need to rethink how they acquire and retain customers. Think about it—why force customers onto an app or website when they can just text you? In Brazil, we’re seeing companies replace entire websites with WhatsApp-driven transactions.

• Need to book a doctor’s appointment? WhatsApp.

• Paying your electricity bill? WhatsApp.

• Ordering food? WhatsApp.

The future is direct, personalized, and instant—and that means messaging.

BANKS WENT FROM FIGHTING WHATSAPP TO RUNNING ON IT.

OM: That brings me to banks. A few years ago, financial institutions were hesitant to touch WhatsApp. Now, they’re all in. What changed?
GH: Security concerns. I saw this firsthand when I was at Banco Votorantim. The bank was flooded with customer service calls—80% of them were just people asking for a boleto. I proposed moving those requests to WhatsApp, and the security team immediately said: “Not safe.”

Fast forward, and today:

✓ Banks now account for over 33% of WhatsApp API usage in Brazil.

✓ Customers are getting loans, changing credit limits, and opening accounts—inside WhatsApp.

What changed? Banks finally realized that:

1. Consumers want chat, not clunky banking apps.

2. Fraud risk on WhatsApp is actually lower than other platforms.

OM: What’s the lesson for fintech founders?
GH: If your fintech strategy doesn’t include conversational interfaces, you’re already behind.

THE BEST TIME TO BUILD.

OM: Let’s zoom out—when you built Agora, Brazil’s leading online brokerage, the market grew 35X. What lessons from that journey still apply today?
GH: Crisis is the best time to build.

When we launched Agora in 2000, the market collapsed 88% over the next three years:

📉 2000: Dot-com bubble burst.

📉 2001: 9/11 shook global markets.

📉 2002: Lula was elected, and the market panicked.

By 2003, the stock market rebounded 97%, and we were perfectly positioned to scale.

HIRING MISTAKE THAT CAN KILL YOUR STARTUP.

OM: Hiring is make-or-break for founders. What’s the biggest mistake you made?
GH: Hiring when I knew it wasn’t the right person. In the early days, I hired people even though I had doubts. The logic was, “We need someone now.” But bad hires drain time and energy—and firing is harder than waiting. If you’re not 100% sure, don’t hire. A wrong hire is worse than an empty seat.

THE NEXT BILLION-DOLLAR THING.

OM: Fast-forward to today, what’s the next big, overlooked opportunity in fintech?
GH: Open Finance + AI. Most fintech founders obsess over credit because that’s where the money is. But Open Finance flips the entire industry’s power structure. The real play isn’t lending—it’s building AI-driven products that let consumers leverage their own financial data.

Think about it:

• Consumers will soon be able to plug their full financial history into any service they choose.

• The startups that use AI to help people manage, invest, and optimize their money will win big.

WATCH OR LISTEN TO THE J CURVE EPISODE WITH GUILHERME ON SPOTIFY:

THE FOUNDER’S MODE.

OM: You’ve been a founder, an investor in 50+ startups, and now a big tech executive. What’s the biggest mindset shift you had to make?
GH: Letting go of the “Founder’s Mode.” Paul Graham wrote about this recently—the difference between being a founder and being a CEO. As a founder, you’re involved in everything. In a big company, that doesn’t work.I had to unlearn micromanagement and trust teams to execute at scale. It’s still tough! But the best founders understand when to step back.

OM: If you had to bet on one founder trait that predicts success, what would it be?
GH: Thinking big—and actually meaning it. Every founder says they’re thinking big. But when you ask “Why?” five times, most don’t have a real answer. The ones who do - they build billion-dollar companies.

FINAL TAKEAWAY.

✓ Crisis is the best time to build – Agora was launched in a downturn when the market dropped 88% in three years. By 2003, it rebounded 97%, and they were perfectly positioned to scale. The best founders play the long game.

✓ WhatsApp didn’t replace business—it became business – More commerce now happens through WhatsApp than traditional e-commerce in Brazil. If you’re still relying on apps and websites, you’re already behind.

✓ The wrong hire costs more than waiting for the right one – Guilherme made the mistake of hiring people he wasn’t sure about. The lesson here is that a bad hire drains time, money, and momentum.

✓ The biggest fintech opportunity isn’t lending—it’s Open Finance + AI – Founders are chasing credit, but the real play is building AI-driven financial tools that put users in control of their data.

✓ Conversational Commerce (C-Commerce) is inevitable – Just like mobile replaced desktops, chat is replacing websites and apps. If your startup isn’t thinking about messaging, you’re missing the shift.

✓ Big companies don’t kill startups—bad timing does – Agora’s biggest risk wasn’t competition; it was being too early. The best timing always feels slightly ahead of the market.

✓ If your idea seems obvious, you’re too late – every major shift—cloud, fintech, AI—sounded crazy before it changed everything. The best founders build what the world doesn’t see yet.

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