#margin

Most explainers stop at 'you borrow a stock and sell it'. That skips the locate requirement, the borrow fee that floats daily, the dividends you owe the lender, the recall that can end the trade for you, and the fact that the proceeds are collateral rather than cash. The bill for all of it grows the longer your thesis takes to work.

Everyone knows 2x leverage wipes you out at a 50% drawdown. Almost nobody does the other calculation: with a 30% house maintenance requirement, the margin call lands at a 28.6% decline. That is an ordinary bad year, not a crash.