Update
Antithesis Raises $105M at $525M Valuation
Antithesis, a software-testing startup based in Tysons Corner, Virginia, has raised $105 million at a $525 million post-money valuation. The company, which previously raised $47 million in a seed round in 2024, is now considering another funding round. The Series A closed on December 3, 2025, with Jane Street, a quantitative trading firm, leading the round. The fresh capital will be used to expand engineering, build out platform autonomy features, and scale sales and marketing efforts across North America, Europe, and Asia. The company's flagship product is a deterministic simulation testing platform built on a deterministic hypervisor.