The Law of One Price dictates that identical assets should be priced identically. However, this assumes an efficient market. Occasionally, when a market becomes temporarily inefficient, identical (or very similar) financial instruments may experience small pricing discrepancies. These differences present what is called an arbitrage opportunity. Simply stated, arbitrage presents the investor with an opportunity for risk-free profit. Typically these opportunities require information regarding the pricing of financial instruments on several exchanges. In addition, there may exist a deviation of information from one source to another, which implies an invalidation of several efficient market hypothesis.