Mark Cuban put $500K into a stranger’s rocket company over email. It’s now a SpaceX competitor worth $4 billion

Mark Cuban has a track record of making bold business bets with limited information. He once bought a $25 million Dallas mansion sight unseen, calling it his one “why the f–k not purchase.” But one of his most lucrative gambles started even more casually: with a cold email from a stranger he says he’s still never met. Speaking in a September 2024 interview with podcaster and comedian Theo Von, Cuban recounted how a young entrepreneur named Tim Ellis—who was also an ex-intern at Blue Origin (Jeff Bezos’ space company) — and his friends emailed him from Dallas, saying they wanted to start a space company. Cuban admitted he had no relevant expertise, but wanted to give them a shot anyway. “I don’t know shit about space, but I’ll get you started and see what happens,” Cuban recalled telling them. That company was Relativity Space. Cuban said the entire relationship played out over email, and he’s still never met Ellis in person. “It was all email, never met him,” he said, but still gave them $500,000 to start. “Now I’ve invested a few million, [and now] they’re worth $4 billion,” Cuban said. At Blue Origin, Ellis started the metal 3D-printing division before founding Relativity, he told TechCrunch—so Cuban was quick to credit the founders for the success of the business rather than himself. “It’s not like I helped them get there,” Cuban said. “These guys were just insanely smart and good. I got lucky … I just got him started.” What Relativity Space actually does Relativity’s pitch is manufacturing disruption: The company 3D-prints the majority of its rockets, aiming to slash parts counts and production time. “In the end, they’re getting better performance and lower costs, which means we can potentially fly our payloads and astronauts safely and at a reduced cost on some of their missions,” Paul Gradl, principal engineer of component development at Marshall, told N