The simultaneous purchase and sale of the same securities, commodities, or foreign exchange in different markets to profit from unequal prices. Arbitrage is the simultaneous purchase and sale of the same asset in different markets in order to profit from a difference in its price.The act of buying and selling goods simultaneously in different markets to gain an immediate profit. Impressive, but tricky. An arbitrage is a transaction that involves no negative cash flow at any probabilistic or temporal state and a positive cash flow in at least one state. Arbitrage in trading is the practice of simultaneously buying and selling an asset to take advantage of a difference in price. Arbitrage is a trading strategy. The goal is to generate profit from slight differences in price between similar, or identical, assets.