Promethus, co-founded by Jeff Bezos, raised a $12 billion Series B, the largest single funding round of 2026, bringing its valuation to $41 billion. The round's size alone makes it an outlier even in a year defined by unusually large AI funding rounds, and Bezos's direct involvement as a co-founder, rather than simply an investor, is itself notable given his primary focus has historically been Amazon and Blue Origin.
A $12 billion single round is large enough that it functions less like traditional venture funding and more like a direct bet on a specific technical thesis being right at a scale few startups ever reach before their first public product launch, raising the stakes considerably on whatever Promethus ships next.