Elon Musk is officially the world's first trillionaire following SpaceX's stock debut today, with the company's IPO price valuing his stake at nearly $870 billion on paper. The stock opened at $150 a share after the rocket and satellite company priced its IPO Thursday night at $135 a share ahead of today's debut on the Nasdaq, trading under the ticker SPCX (SPCX). Musk holds approximately 42% of SpaceX's equity through a dual-class share structure that grants him roughly 82% of voting control via Class B stock. With shares around $158 in midday trading, his equity stake is valued at $869.4 billion. Musk holds ... (full story)