Leverage

Leverage means using borrowed money or financial instruments to control a larger position than your own capital alone would support. It multiplies outcomes in both directions: a leveraged bet that goes well produces outsized gains, and one that goes badly produces outsized losses, sometimes losses larger than the original money put in. Leverage shows up everywhere in finance, from an ordinary mortgage (a small deposit controlling an entire property) to hedge funds borrowing heavily to amplify a trade. It's a genuinely useful tool and also the common thread running through most major financial blowups.