Nubank

Sierra

Nubank

Nubank makes money from credit card interchange fees (1-3% of every transaction), interest on credit card balances and personal loans, and net interest income from deposits (lending out customer deposits at higher rates than it pays in savings interest). The company also earns fees from insurance products and investment marketplace commissions.

The key insight is that by being digital-only with no branches, Nubank's cost to serve a customer is roughly 85% lower than traditional Brazilian banks.

Sierra

Companies pay Sierra to run their customer service with AI agents instead of hiring rooms full of humans. The agent talks to your customers over chat.

It answers questions. It processes returns.

It updates subscriptions. Here is the clever part.

Sierra charges based on outcomes, not seats. Brands pay when the AI actually resolves a problem, not just for having the software installed.

That pricing is unusual. Most software charges a flat monthly fee no matter what.

Sierra only gets paid when the bot does the job.

Nubank

David Vélez grew up in Colombia, studied at Stanford Business School, and worked at Sequoia Capital in Silicon Valley. In 2012, Sequoia sent him to Brazil to find investment opportunities.

What he found instead was the worst banking experience he'd ever encountered.

Brazilian banks were controlled by five massive institutions that charged outrageous fees — annual credit card fees of $200+, account maintenance fees, fees on fees. Customer service was a nightmare.

Branches required hours of waiting. The banks had zero incentive to improve because they had a captive market of 200 million people and no competition.

Vélez saw the opportunity and left Sequoia to start Nubank in 2013 with Cristina Junqueira (a former Itaú banker) and Edward Wible (a Princeton engineer). Their first product was a purple credit card — no annual fee, managed entirely through a beautiful app, with transparent billing and real-time notifications.

In a country where banks treated customers like an inconvenience, Nubank treated them like human beings.

Sierra

Bret Taylor had already done the impossible twice. He co-created Google Maps.

He later became co-CEO of Salesforce, chaired Twitter's board during the messy Elon Musk takeover, and became chairman of OpenAI in late 2023. Clay Bavor spent 18 years at Google, most recently running its Labs group.

The two friends left their big jobs in 2023 to build something together. They picked customer service on purpose.

It is the least glamorous corner of software. Their logic was simple.

Companies hate their support costs. Customers hate waiting on hold.

AI that actually resolves problems could fix both sides at once. They launched Sierra in February 2024 with $110 million from Sequoia and Benchmark.

Nubank

Nubank grew through word of mouth in a country where everyone hated their bank. The product was so much better than the alternative that customers became evangelists.

The invite-only launch created exclusivity and a waitlist that hit millions. People would beg friends for an invite code because getting a Nubank card felt like escaping prison.

The cost advantage was structural. Traditional Brazilian banks operated thousands of branches with tens of thousands of employees.

Nubank had an app and a customer service team. This let Nubank offer free products that banks charged hundreds of dollars for.

The unit economics were unbeatable — when your competitor has 4,000 branches and you have zero, you can afford to be generous.

Geographic expansion into Mexico and Colombia replicated the playbook. Both countries had the same banking problem — concentrated, fee-heavy, customer-hostile banks.

Nubank launched in Mexico in 2019 and Colombia in 2020. Mexico alone already has over 8 million Nubank customers.

Sierra

Sierra went straight for big brands, not tiny startups. SoFi, Ramp, ADT, Sonos and Brex signed up early.

By 2026 it said more than 40% of the Fortune 50 were customers. The trick was trust.

Enterprises are terrified of an AI bot going rogue and insulting a customer. So Sierra built guardrails and let each company control exactly how the agent behaves.

Bret Taylor's contacts did the rest. When the chairman of OpenAI calls a Fortune 500 CEO, they pick up.

Sierra hit $100 million in annual recurring revenue in November 2025, seven quarters after launch, and $150 million by February 2026. In April 2026 it launched Ghostwriter, which builds and deploys a new agent from a plain-English description.

Nubank

The IPO timing was terrible. Nubank went public on the NYSE in December 2021 at a $41 billion valuation.

The stock immediately crashed as the global tech sell-off hit and rising interest rates in Brazil increased the cost of capital. The stock fell from $12 to under $4 by mid-2022.

Vélez had to spend a year convincing investors that a Brazilian digital bank was worth owning during a global risk-off environment.

Credit risk in Latin America is inherently higher. Brazil has volatile inflation, currency risk, and a large unbanked population with limited credit history.

Nubank's loan book grew rapidly, and delinquency rates spiked in 2022 as Brazil's economy slowed. Managing credit risk at scale in emerging markets is fundamentally harder than in developed economies.

Nubank has since tightened underwriting and delinquency has improved, but it remains the biggest operational risk.

Regulatory complexity across three countries is a constant headache. Brazil, Mexico, and Colombia each have different banking regulations, consumer protection laws, and compliance requirements.

Navigating three regulatory environments simultaneously while growing at speed requires significant legal and compliance investment.

Sierra

Everyone is building AI customer service agents right now. Decagon has raised at a multi-billion valuation.

Salesforce, ServiceNow and Intercom all shipped their own agents. Sierra is not the cheap option.

It sells premium AI to giant companies that move slowly. The bigger risk sits underneath the product.

Sierra does not make its own AI models. It rents them from providers like OpenAI and Anthropic.

If those model makers decide to compete directly, Sierra's edge gets thin fast, and its co-founder chairing one of them only makes that question louder. A $15.8 billion valuation on roughly $150 million in revenue leaves almost no room for a stumble.

Nubank

Nu Credit Card is the flagship — a no-annual-fee Mastercard managed entirely through the app. NuConta is the digital bank account with free transfers and bill payments.

Nu Invest is the investment platform offering stocks, ETFs, and fixed income. Personal Loans are offered based on credit behavior within the app.

Nu Life Insurance and other insurance products are distributed through the app. Ultraviolet is the premium tier with higher limits, airport lounges, and additional perks.

NuPay is the payments solution for merchants.

Sierra

The core product is the Sierra AI agent. It is a branded customer service bot that companies deploy on their website, app, and phone lines.

It handles the boring stuff. Order tracking.

Refunds. Password resets.

Account changes. Sierra also built its own tools to test and monitor these agents so they do not make things up.

In 2024 the company added a voice version that talks to customers on the phone. In April 2026 it added Ghostwriter, a tool that builds and deploys a new agent from a plain-English description.

The whole pitch is one AI agent that carries your brand's name and never sleeps.

Nubank

Sequoia Capital, Tiger Global, DST Global, Tencent, Berkshire Hathaway, SoftBank, Dragoneer

Sierra

Sequoia Capital and Benchmark wrote the first checks at launch in February 2024, $110 million between them. Greenoaks Capital then led both the $175 million round in 2024 and the $350 million round in September 2025.

In May 2026 Tiger Global and Google's GV led a $950 million round at a $15.8 billion valuation, with Benchmark, Sequoia and Greenoaks back in. That takes total funding to about $1.6 billion.

That is partly the product and partly Bret Taylor. Investors bet on founders who have already built billion-dollar things.