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- Tech billionaire Michael Dell jabbed at his old rival Carl Icahn this week.
- Dell mocked Icahn Enterprises' plunging stock price in a post on X.
- Shares in Icahn's holding company have crashed 63% this year, dragged down by an attack from short-seller Hindenburg Research.
Michael Dell took a shot at his old foe Carl Icahn Tuesday, mocking the investing legend's struggles this year in the latest twist in a decade-old feud between the two tycoons.