Law of one price

In economics, the law of one price (LOOP) states that in the absence of trade frictions (such as transport costs and tariffs), and under conditions of free competition and price flexibility (where no individual sellers or buyers have power to manipulate prices and prices can freely adjust), identical goods sold at different locations should be sold for the same price when prices are expressed in a common currency. This law is derived from the assumption of the inevitable elimination of all arbitrage. See Rational pricing § The law of one price.