He founded Instinct, an AI assistant startup, just last year. Since then, its valuation has skyrocketed. The company raised $250 million at a $2.5 billion valuation in August, bringing its total raised at the time to $350 million. Just this week, the company raised an additional $1 billion in a Series C that shot its valuation up to $10 billion. 

Even though Instinct’s AI assistant is open only to a select few invitees, Instinct is now approaching $1 billion in annual transaction volume, Shinn said in an interview on the Invest Like the Best podcast published Monday. 

Despite not being broadly available, Instinct has grown organically through word of mouth, Shinn told the podcast host and venture capitalist Patrick O’Shaughnessy. So many people want to join, he said, that existing users are now selling invitations to join Instinct on eBay. 

“We spent $0 on marketing so far,” he said.

What does Instinct do?

Instinct is a free personal assistant powered by AI that can communicate with users via message or a phone call. The assistant launched in private beta in February, The Wall Street Journal reported, but last month opened in an invite-only beta, with each user allotted five invites. It has caught on with people who have used the tool to plan weddings and cancel hundreds of dollars worth of subscriptions, Shinn said in an X post last month. 

The Instinct founder said his personal assistant and others like it have the potential to simplify users’ lives, especially when it comes to travel—a category which makes up half of the billion dollars Shinn said is transacting through the platform on a yearly basis—by learning users’ preferences and storing it in its memory.

“It will be able to use that memory and be able to, you know, now make it a much easier experience for you in the future to be able to book that according to exactly what you want,” he said on the podcast.

Taking on Meta

Instinct may have raised hundreds of millions of dollars in funding, but what may say the most about the excitement surrounding it is that the company has also caught the eye of Meta chief AI officer Alexandr Wang, who has poked fun at the company several times in X posts since Meta announced its own personal AI agent, Muse, earlier this month. 

Wang, who became a billionaire after founding Scale AI, which Meta later put $14.3 billion into, replied to several posts comparing Muse and Instinct. In one, he said Muse would beat Instinct in an MMA match, while in another he wrote “Muse is way hotter than the other personal agents (and also way faster, but mostly hotter)” in response to another users’ post that meme’d the choice between Instinct and Muse.

Wang last week replied to one more post by mocking Instinct’s name: “Muse absolutely crushes Insect,” he wrote. Shinn reportedly replied to one of Wang’s multiple posts with a smiley face.

Instinct did not immediately reply to Fortune’s request for comment. Meta did not immediately reply to Fortune’s request for comment. 

It’s unclear how many users Instinct has at the moment, but Muse, for its part, has already attracted a huge following of its own and recently replaced ChatGPT as the top free app on the U.S. App Store. Estimates from market intelligence provider Apptopia found that Muse saw 2.8 million installs worldwide in its first 12 days, TechCrunch reported.

Shinn said in the interview with O’Shaughnessy that he believes Muse is a great product but that he spends “very little of my time thinking about competition and other players in the space.” 

He said right now the potential for growth is huge because many people, even if they use AI, aren’t using it to its highest potential.

“It’s still an exciting time,” he said. 

Wang’s posts, though, may have also given Instinct a marketing boost. Combined, Wang got hundreds of thousands of views and more than 1,000 likes on his posts related to Instinct.

Who is Noah Shinn?

Despite the tension, Shinn and Wang have one thing  in common. Like many successful tech founders, they both dropped out of college.

Shinn grew up in the San Francisco Bay Area and went to a private high school in San Jose, Business Insider reported. In high school, he played basketball and also ran cross country. He attended Northeastern University in Boston, but left in 2023 to join the startup world.

But Shinn’s work on AI agents began even before he dropped out.

As a student, Shinn had varied interests. He worked on type prediction and code generation in Northeastern’s Programming Language Group, researched excited-state molecular dynamics in the university’s Computational Photochemistry Group, and was also member of the avionics team in Northeastern’s student-run aerospace organization, according to his personal website.

But he established himself as a serious AI researcher when he authored a paper as an undergraduate with then-Massachusetts Institute of Technology professor Ashwin Gopinath, called “Reflexion: Language Agents with Verbal Reinforcement Learning.” The paper explored how AI agents could learn from previous responses by having them reflect on feedback and store the data in memory to do better next time. 

In a blog post co-written with Gopinath, the pair wrote that their proposed method, “mirrors human problem-solving.”

Shinn and his co-authors used the Reflexion approach they proposed to get a large language model to achieve 91% accuracy, compared to 80% accuracy with GPT-4, on a coding evaluation by asking it to check its responses. The paper has been cited hundreds of times, including by Google Deepmind, according to an article published by Northeastern’s Khoury College of Computer Sciences. And in 2023, Shinn and his co-authors presented their findings in 2023 at NeurIPS, a leading academic AI conference. 

In 2023, Shinn also left university to join AI startup Sierra as one of the company’s first employees. Sierra, an enterprise AI intelligence platform, creates AI agents and was cofounded by OpenAI’s chairman, Bret Taylor.

Instinct is now making its own AI personal assistants and competing directly with Muse, which is backed by Meta’s massive resources. Shinn meanwhile, said in a post last month the company was keeping Instinct invite only while it was “actively bringing up more compute.” 

Shinn’s company may lack Meta’s enormous resources, but its rapid rise shows agents are opening up as AI’s newest battleground where opportunities abound.