Jane Street Leads Antithesis's $105M Series A to Make Deterministic Simulation Testing the New Standard

A unique investment from the quant trading giant signals a shift in how complex systems will be tested.

TYSONS CORNER, Va., Dec. 3, 2025 /PRNewswire/ -- Antithesis today announced a $105 million Series A round led by Jane Street, the global technology-driven quantitative trading firm known for building some of the world's most advanced software systems. The investment underscores Antithesis's emergence as critical infrastructure for enterprises operating complex, distributed systems. Jane Street is both an Antithesis investor and customer.

Additional investors include Amplify Venture Partners, Spark Capital, Tamarack Global, First In Ventures, Teamworthy Ventures, Hyperion Capital, and individuals including Patrick Collison, Dwarkesh Patel, and Sholto Douglas, alongside other new and returning investors. The capital will be used to accelerate Antithesis's product innovation and scale its go-to-market operations across North America, Europe, and Asia.

Software systems have grown more complex, and as AI accelerates the volume of code being produced, traditional testing cannot keep pace. Today, most organizations still rely on example-based tests (whether written by engineers or by AI). These methods catch surface-level issues but cannot reliably expose the deep, emergent behaviors that cause outages, data corruption, and cascading system failures.

Antithesis replaces this with deterministic simulation testing: running a fully automated, massively parallel simulation of the system being validated that compresses months of production behavior into hours. The platform explores edge cases, injects common faults, validates correctness, and perfectly reproduces any failure so engineers can fix issues with unprecedented speed and confidence.

"Software now underpins everything, and as systems become more complex and distributed, the world needs a new testing model that guarantees correctness," said Will Wilson, CEO of Antithesis. "With this funding, we're expanding the infrastructure that makes reliability not just achievable, but expected, just as we expect traffic lights to work every time. Our customers are already proving that deterministically validated systems ship faster, without breaking, and earn deeper trust."

"Jane Street runs some of the most demanding distributed systems in the world, and Antithesis has helped us uncover issues that no other testing method could find," said Doug Patti, Engineer at Jane Street. "We hold a very high bar for the technology we rely on, and an even higher bar for the companies we choose to invest in. While leading an early round is rare for us, Antithesis is years ahead, and we believe deterministic simulation testing will become foundational across industries."

Customer impact across finance, AI, blockchain, and data infrastructure
Antithesis is already used by organizations whose systems cannot fail:

• Jane Street depends on Antithesis to validate complex distributed systems critical to the operation of its global trading business.
• Ethereum used Antithesis to simulate its global network under extreme conditions ahead of The Merge, uncovering critical issues that could have jeopardized the historic Proof-of-Stake transition.
• MongoDB uses Antithesis to rigorously test core components of its database platform, helping engineers catch subtle issues before they reach customers.

These examples reflect a rapidly expanding customer base across finance, infrastructure platforms, and organizations building advanced AI systems. Antithesis has increased revenue by over 12x over the last two years and continues to grow rapidly.

Use of proceeds
With the new funding, Antithesis will:

• Expand engineering teams to strengthen its deterministic simulation engine
• Advance platform intelligence and autonomy
• Build a world-class sales and marketing organization
• Scale GTM operations across North America, Europe, and Asia
• Deepen availability through cloud channels, including AWS Marketplace

About Antithesis
Antithesis is a fundamentally new way to validate that software works correctly before it is released. It conducts a fully deterministic, massively parallel simulation that tests years of real-world production in a few hours. Antithesis intelligently explores the far corners of your codebase, strategically injecting common faults to ensure the system always behaves as intended. The platform perfectly reproduces any bug it finds in its one-of-a-kind environment for rapid debugging. The company is based in Northern Virginia, was founded in 2018, and launched out of stealth in 2024. For more information, visit https://antithesis.com/.

About Jane Street
Jane Street is a global technology-driven trading and investment firm. Founded in 2000, the firm brings a research-driven approach and quantitative expertise to markets worldwide, with over 3,000 employees across offices in New York, London, Hong Kong, Singapore, and Amsterdam. For more information, visit www.janestreet.com.

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