unusual property that their notional changes every day; they pay the compounded daily return, so it is as if one were re-investing each day's earnings at the new daily price. If an investor has an inverse ETF in an asset that goes down, they will have more money, which can be used to short a cheaper asset, hence one's unit notional goes up. Conversely, if the asset has gone up in value in this situation, the notional will go down, as seen in inverse exchange-traded funds, Notes External links Chicago Mercantile Exchange: Glossary Derivatives (finance) Interest rates Swaps (finance)