The IPO market is about to face its most consequential test in decades. SpaceX, Elon Musk’s aerospace, satellite, and artificial intelligence conglomerate, is targeting a June 12 Nasdaq debut under the ticker SPCX — aiming to raise as much as $75 billion at a valuation approaching $1.75 trillion. If it prices at that level, it would shatter Saudi Aramco’s 2019 record of $35.4 billion as the largest initial public offering ever completed.