Flapping Airplanes, a research-focused startup that’s trying to find ways to use less data to train AI models, is in talks to raise capital at a $5 billion valuation, multiple sources familiar with the deal told Forbes. VC firms Index Ventures and Lux Capital are leading the round and Kleiner Perkins is participating, the sources said. The raise is in the hundreds of millions, they added.

Flapping Airplanes did not respond to Forbes’ request to comment. Index Ventures, Lux Capital and Kleiner Perkins declined to comment.

The San Francisco-based startup was cofounded in 2025 by brothers Ben........

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