Alphabet Inc. is set to book another sizable paper gain after SpaceX completes a tender offer that effectively values the closely held company at about $800 billion.

SpaceX’s insider share sale was priced at $421 a share, Bloomberg reported Friday, which would mark a sharp jump in valuation from earlier secondary transactions. That is likely to lift the carrying value of Google’s long-standing investment in Elon Musk’s rocket and satellite company.