Icahn, Others Clean Up on Musk’s Twitter About-Face

Elon Musk’s decision to end his war with Twitter isn’t just a big win for the social-media company, but also for some big-name investors like Carl Icahn.

Mr. Icahn quietly amassed a Twitter stake of well over $500 million in the past few months and made a sizable profit Tuesday after the shares shot up on news that Mr. Musk offered to close his $44 billion purchase of the social-media giant on the original terms, according to people familiar with the matter.