Flapping Airplanes, a San Francisco AI research lab founded in late 2025, has raised $1 billion at a $6 billion valuation. Index Ventures and Lux Capital led the round, with Sequoia Capital, Alphabet's GV and Kleiner Perkins also participating.
The new valuation is four times the price Flapping Airplanes set in January, when it raised a $180 million seed round. The company has no product on sale yet, and no public benchmarks or named customers.
The lab is researching ways to train AI models with less data and less computing power, and to get more performance out of the chips that run them. Part of that work involves writing its own version of the software that runs Nvidia's graphics chips. The company's thesis is that demand for AI will outpace the supply of both chips and data, and it plans to eventually sell its technology so other companies can run AI more cheaply. Getting 10% more performance out of each chip would be "tremendously economically valuable," co-founder Asher Spector said.
Key facts
- 01Flapping Airplanes raised $1 billion at a $6 billion valuation in a round led by Index Ventures and Lux Capital.
- 02The valuation is four times the level set by its $180 million seed round in January.
- 03Sequoia Capital, GV and Kleiner Perkins also participated; the company counts Nvidia among its backers.
- 04The San Francisco lab, founded in late 2025, has no product on sale yet.
- 05Its research targets training AI with less data and compute and getting more performance out of each GPU.
The technical approach centers on megakernels, which combine many operations into one long-running GPU program with an internal scheduler handling computation, memory transfers and communication. That cuts down on repeated kernel launches and round trips to the host processor. Flapping Airplanes says its framework can run an entire training run inside a single kernel while also serving inference, and describes a "Kittens" virtual machine that schedules multiple workloads on the GPU. No public code or benchmarks yet allow those claims to be tested independently.
The company was founded by brothers Ben and Asher Spector along with Aidan Smith. Ben Spector earned his PhD at Stanford under Chris Ré, where his work included ThunderKittens, a library for writing high-performance GPU kernels developed through Stanford's Hazy Research group, as well as megakernels and AI scaling laws. Asher Spector previously worked at Cursor, Mercor and Meta, and Smith is a Thiel Fellow and former Neuralink engineer.
The name refers to the ornithopter, an early aircraft design with flapping wings. Asher Spector said it stands for combining the strengths of natural and artificial intelligence.
The round puts Flapping Airplanes among a group of research-first AI startups, sometimes called neolabs, that are raising large sums before shipping a product. Yann LeCun's AMI Labs raised about $1 billion in March, Mirendil raised $200 million in June, and Flourish, run by Internet Explorer co-creator Thomas Reardon, was reported in May to be raising about $500 million for energy-efficient, brain-inspired AI.
Index Ventures, one of the two leads on this round, raised $2 billion in August to back more AI companies.
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