SpaceX’s Bumpy Ride on the Stock Market May Get Bumpier

The shackles are soon coming off SpaceX’s stock.

On Thursday, the first “lockup” on shares of Elon Musk’s rocket company is set to expire, which means employees and other company insiders who were prevented from trading the stock after SpaceX’s initial public offering in June will be able to do so. Lockups are put in place after an offering to prevent shares from flooding the market and driving down their price.

SpaceX employees and early investors will now have the opportunity to cash in on millions of dollars in gains from their company stock. But for everyone else, the end of the lockup comes at a delicate time.

In the seven weeks since SpaceX went public, its stock briefly soared before falling nearly 50 percent from its high, dropping well below its $135 public offering price. Once the lockup ends, 912 million shares will become available — more than double the current supply that can be traded — which may further depress the price.

“There are reasons to be concerned that the expiration of the lockup will introduce more price volatility,” said Patrick Corrigan, a law professor at the University of Notre Dame, who has studied initial public offerings. On average, he added, the end of lockups leads to a 1.5 percent drop in stock prices because of increased selling.

How SpaceX’s stock fares after the expiration of its various lockups is likely to serve as a benchmark for other major tech companies that may go public in the next 12 months, including the artificial intelligence start-ups Anthropic and OpenAI. In June, Mr. Musk’s company held the world’s biggest I.P.O., raising $85.7 billion and rising nearly 20 percent on its first day of trading to be worth more than $2 trillion. The event turned Mr. Musk, who controls more than 80 percent of SpaceX’s shareholder votes, into the world’s first trillionaire and seemed to signal investor appetite for more technology I.P.O.s.

But SpaceX’s volatile stock performance since then is a reminder that going public is no easy feat. The company, which has a market value of $1.428 trillion, has been buffeted by investor skepticism and a growing number of “short” sellers, who borrow shares to bet on a stock’s decline.