With a valuation of $350 billion, Elon Musk’s SpaceX remains a private company. WSJ reporter Corrie Driebusch explains how a tightknit circle of Musk allies control its shares, as well as those of the businessman’s other private companies. Plus, WSJ columnist Sumathi Reddy takes us through the painstaking decision of whether to buy her 11-year-old daughter a smartphone. Katie Deighton hosts.

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