 Numéraire

A numéraire is a strictly positive traded asset used as the unit in which all other asset prices are expressed. Changing the numéraire changes the associated martingale measure while preserving no-arbitrage prices.

Numéraire is a term used in economics, finance, and mathematics to refer to a unit of account or a standard numerical value that is used to measure the value of goods, services, or financial assets. In a broader sense, it acts as a common denominator that facilitates comparisons of value across different items. In the context of finance, numéraire can refer to a specific reference asset or currency used to express the value of other assets.