Say you expect shares in a company to lose value, you could borrow 1000 shares at €10 a share, sell them for €10,000, wait until the share drops to, say, €9, buy back 1000 shares for €9,000, return the shares and pocket €1000 in profit.
Kad akciju cena ir kritusies, teiksim līdz 9 € par akciju, jūs atpērkat šīs pašas1000 akcijas par 9000 € un atdodiet tās atpakaļ.