Elon Musk's SpaceX and its investors have agreed to buy shares from its employees, valuing the business at $350bn.The transaction values SpaceX at approximately $350bn, doubling its reported value a year ago.SpaceX and its investors will buy up to $1.25bn worth of employees' shares, with the company alone offering to snap up $500m.Elon Musk's personal fortune has soared to $384bn, and his other business interests include AI startup xAI and brain implant firm Neuralink.