The $2B AI Startup Simulating Human Behavior with 85% Accuracy

What if AI could predict human behavior before it happens?

I sat down with Joon Sung Park, Co-Founder & CEO of Simile, the $2B AI startup building foundation models of human behavior, backed by Greenoaks, Index Ventures, + investors including Fei-Fei Li & Andrej Karpathy.

Simile is building digital twins of real people to simulate how individuals, consumers, and entire populations make decisions. Its foundational Stanford research demonstrated 85%+ accuracy in predicting human behavior, and today the company has partnerships providing access to over 40 million real people globally.

Companies including CVS, Wealthfront, Deloitte, and Banco Itaú are already working with Simile to understand their customers, test products, optimize messaging, and simulate decisions before deploying them in the real world.

Recorded at Index Ventures in San Francisco, we discuss how Joon's original Stanford research, Smallville, evolved from 25 autonomous AI agents into a $2B company, why human behavior is more predictable than we think, and how simulations could transform traditional market research, corporate strategy, and decision-making.

We also put Simile to the test. Before our interview, Joon simulated our conversation using AI, and the model correctly anticipated one of my opening questions.

Joon Sung Park: https://x.com/joon_s_pk

Molly O’Shea: https://x.com/MollySOShea

Sourcery: ⁠https://x.com/sourceryy

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YouTube: ⁠https://youtu.be/-6Kg5N7JL7I⁠

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