Okay, so two siblings left OpenAI because they wanted to make a safer AI company, and just this month, they passed OpenAI in revenue.
This is part two in a series explaining the real story behind the 30 most valuable private tech companies.
Anthropic started as an OpenAI breakup in 2020 when a brother, VP of Research Dario Amodei, and his sister Daniela, a VP of Safety and Policy, left OpenAI together.
They wanted to build a new AI company more focused on alignment and safety.
They also had a vision for a different technical approach to AI, too.
OpenAI uses a process called RLHF, where the model's answers pass through a panel of real humans who rate them to decide which is better before providing an output.
Anthropic pioneered constitutional AI, where humans wrote an overarching constitution for the model to guide its behavior, and then the model checks itself against that constitution.
Is this truthful?
Is this violent?
The resulting output is less likely to go off the rails, and enterprise legal and compliance teams often trust more.
In just four years, Anthropic has raised nearly $64 billion, about half as much as OpenAI.
$38 billion from large VCs, $10 billion from NVIDIA, $8 billion from Amazon, $5 billion from Microsoft, $3 billion from Google.
The company has seen tremendously fast revenue growth.
In just 16 months, from December 2024 to April 2026, OpenAI grew from $6 to $24 billion, while Anthropic pulled from behind at $1 billion and flew to $30 billion, overtaking OpenAI just this month.
The revenue grew quickly for two reasons.
First, they won the enterprise.
Eight of the Fortune 10 are now Claude customers.
Over 500 companies spend more than a million on it annually.
And second, Claude Code, a popular AI coding agent, was introduced in May 2025.
It was an overnight hit.
But it's not without controversy.
This spring, Anthropic got into it with the government when they refused to remove restrictions on using Claude for autonomous weapons and domestic surveillance.
The Pentagon then labeled Anthropic a supply chain risk.
This is the same thing they do for adversarial foreign companies.
Some say they took a principled stand.
Others label it a business risk.
Both OpenAI and Anthropic are speedrunning toward an IPO.
It's anyone's guess who's going to go first and who's going to go farthest.
Which company on this list do you want to see unpacked next?
OpenAI’s not so little brother: Anthropic
Here’s part 2 in unpacking the most valuable private tech companies (by secondaries demand)
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