Corporate activist Carl Icahn’s fortune tumbled more than $10 billion Tuesday after short-seller Hindenburg Research accused him of using a “ponzi-like” economic structure at his investment company. Icahn Enterprises L.P., his publicly traded limited partnership that operates as a holding company, fell by 20% — the most on record — erasing $3.1 billion from his fortune. Hindenburg also detailed the investor’s margin loan collateralized by his stake in the company, which was not previously accounted for by the Bloomberg Billionaires Index. That lopped off another $7.3 billion from the net worth calculation. All told, ... (full story)