CoreWeave Inc.'s March initial public offering has been a roaring success for anyone lucky enough to get in at the start. The stock more than quadrupled by mid-June. Even after a recent selloff, the shares are still up nearly 150%.

The problem, though, is most of those early investors haven't been able to cash in.

That changes Friday for holders of more than 80% of CoreWeave's Class A shares, with the IPO lockup expiring two days after its second earnings as a public company. The stock has plunged 33% in those two days, in part, analysts say, in anticipation ...