It is an operation without equivalent in the history of finance. The Californian space company SpaceX – created and owned by Elon Musk – is taking its first steps on the American stock market with stratospheric figures: 555 million shares and a valuation estimated between $1,765 and $2,000 billion, or nearly a hundred times the company's turnover in 2025. Why such enthusiasm? Are we at risk of a space bubble?