For two days, SpaceX was one of the five most valuable companies on Earth. On Thursday, the market began to reconsider. Shares in Elon Musk’s rocket-and-satellite company fell more than 6%, last trading down 6.5% at $178.50, as the frenzy that followed the largest initial public offering in history started to cool.

The drop was steep but the altitude remained high. Even after Thursday’s fall, the stock sat more than 30% above its $135 offering price, the level at which SpaceX priced the IPO that raised $75bn.

The shares had soared in their first two sessions, briefly carrying SpaceX’s market capitalisation past Amazon and, for a moment, Microsoft, before investors began asking whether the valuation could hold.

At around $2.52 trillion, the company’s market value would shrink by more than $150bn on Thursday alone if the losses held into the close. Numbers of that size move with the broader narrative as much as with any single data point, and the narrative this week shifted from triumph to scrutiny.

The 💜 of EU techThe latest rumblings from the EU tech scene, a story from our wise ol' founder Boris, and some questionable AI art. It's free, every week, in your inbox. Sign up now!The question hanging over the stock is the one that hangs over most richly valued listings: what, exactly, justifies the price.