Robinhood

Sierra

Robinhood

Robinhood makes money in ways that don't involve charging users directly. The biggest revenue source is payment for order flow (PFOF) — when users place a trade, Robinhood routes it to market makers like Citadel Securities, who pay Robinhood for the right to execute the trade.

This generates hundreds of millions annually. Robinhood also earns interest on uninvested cash sitting in user accounts, margin lending (charging interest when users borrow money to trade), and Robinhood Gold — a $5/month subscription for larger instant deposits, professional research, and higher interest on cash.

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.

Robinhood

Vlad Tenev and Baiju Bhatt met as physics and math students at Stanford. After graduating, they moved to New York and started two fintech companies that sold trading software to hedge funds.

While building tools for Wall Street, they noticed something absurd: it cost brokerages essentially nothing to execute a trade electronically, but they were charging retail investors $7-10 per trade.

The math was simple. Electronic trading had driven costs to near zero, but brokerages kept the old pricing because customers didn't know better.

Tenev and Bhatt thought: what if we just charged zero? In 2013, they founded Robinhood with the explicit mission of democratizing finance — giving everyone access to the stock market with no commissions, no minimums, and a beautiful mobile app.

The app launched in 2014 with a waitlist that hit 1 million people before the product was even available. The pink-and-green design, the confetti animation when you made a trade, and the simplicity of the interface made investing feel approachable.

For millions of young Americans who had never bought a stock, Robinhood was the entry point.

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.

Robinhood

Robinhood grew by making investing feel like a game. The app was designed to be addictive — swipe to trade, confetti for your first purchase, notifications about stock movements.

It was investing designed for the smartphone generation. Critics called it "gamification of finance." Users called it the first trading app that didn't feel like it was designed in 1997.

The referral program was massive. Both the referer and the new user got a free stock when someone signed up.

People were getting free shares of Apple or Ford just for downloading the app. It spread through college campuses like wildfire.

By 2020, the average Robinhood user was 31 years old — decades younger than the average brokerage customer.

Zero commissions forced the entire industry to follow. In October 2019, Charles Schwab, TD Ameritrade, E-Trade, and Fidelity all dropped their trading commissions to zero within days of each other.

Robinhood had single-handedly destroyed the commission-based brokerage model that had existed for decades.

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.

Robinhood

GameStop was the worst week in Robinhood's history. In January 2021, Reddit's r/WallStreetBets community drove GameStop stock from $20 to $483.

Millions of Robinhood users were buying. Then on January 28, Robinhood restricted buying of GameStop and several other meme stocks.

Users could only sell, not buy. The stock crashed.

The backlash was nuclear. Users accused Robinhood of siding with hedge funds against retail investors.

Vlad Tenev was dragged before Congress. The real reason was less sinister but equally damaging — Robinhood's clearinghouse (DTCC) demanded $3 billion in additional collateral due to the extreme volatility, and Robinhood didn't have it.

They had to raise $3.4 billion in emergency funding over a weekend. The company that built its brand on democratizing finance had restricted the most democratic stock trade in history.

The payment for order flow controversy never goes away. Critics argue that PFOF creates a conflict of interest — Robinhood profits by routing user trades to market makers rather than getting users the best possible price.

The SEC has considered banning PFOF entirely. If that happens, Robinhood loses its largest revenue source.

Post-IPO performance was brutal. Robinhood went public in July 2021 at $38 per share.

The stock briefly hit $70 on meme stock momentum, then cratered to under $8 by mid-2022 — a 90% decline. The company laid off 9% of staff in April 2022 and another 23% that August.

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.

Robinhood

Robinhood is a stock, options, and crypto trading app. The core product lets you buy and sell stocks, ETFs, and options with zero commissions.

Robinhood Crypto adds trading for Bitcoin, Ethereum, and other cryptocurrencies. Robinhood Gold is the premium tier — higher interest on cash, larger instant deposits, and Morningstar research reports.

Robinhood Cash Card is a debit card that earns cashback and rounds up purchases to invest spare change. Robinhood Retirement offers IRA accounts with a 1% match on contributions.

Robinhood Legend is their new desktop trading platform aimed at active traders.

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.

Robinhood

Sequoia Capital, Ribbit Capital, NEA, Index Ventures, Andreessen Horowitz, DST Global, D1 Capital

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.