What Is Arbitrage?

Arbitrage is the purchase and sale of an asset in order to profit from a difference in the asset's price between markets. It is a trade that profits by exploiting the price differences of identical or similar financial instruments in different markets or in different forms. Arbitrage exists as a result of market inefficiencies and would therefore not exist if all markets were perfectly efficient.

Key Takeaways Arbitrage is a type of trade in which a security, currency, or commodity is nearly simultaneously bought and sold, in different markets.

The purpose of arbitrage is to take advantage of the difference in prices available for the same financial instrument being offered on different exchanges.

Arbitrage is not only legal in the United States, but is also considered useful to markets as it helps promote market efficiency and also provides liquidity for trading.

Understanding Arbitrage

Arbitrage occurs when a security is purchased in one market and simultaneously sold in another market at a higher price, thus considered to be risk-free profit for the trader. Arbitrage provides a mechanism to ensure prices do not deviate substantially from fair value for long periods of time. With advancements in technology, it has become extremely difficult to profit from pricing errors in the market. Many traders have computerized trading systems set to monitor fluctuations in similar financial instruments. Any inefficient pricing setups are usually acted upon quickly, and the opportunity is often eliminated in a matter of seconds. Arbitrage is a necessary force in the financial marketplace.

To understand more about this concept and different types of arbitrage, read Trading the Odds With Arbitrage.

A Simple Arbitrage Example

As a simple example of arbitrage, consider the following. The stock of Company X is trading at $20 on the New York Stock Exchange (NYSE) while, at the same moment, it is trading for $20.05 on the London Stock Exchange (LSE). A trader can buy the stock on the NYSE and immediately sell the same shares on the LSE, earning a profit of 5 cents per share. The trader could continue to exploit this arbitrage until the specialists on the NYSE run out of inventory of Company X's stock, or until the specialists on the NYSE or LSE adjust their prices to wipe out the opportunity.

Types of arbitrage include risk, retail, convertible, negative, statistical, and triangular, among others.

A Complicated Arbitrage Example

Though this is not the most complicated arbitrage strategy in use, this example of triangular arbitrage is more complex than the above example. In triangular arbitrage, a trader converts one currency to another at one bank, converts that second currency to another at a second bank, and finally converts the third currency back to the original at a third bank. The same bank would have the information efficiency to ensure all of its currency rates were aligned, requiring the use of different financial institutions for this strategy.

For example, assume you begin with $2 million. You see that at three different institutions the following currency exchange rates are immediately available:

Institution 1: Euros/USD = 0.894

Institution 2: Euros/British pound = 1.276

Institution 3: USD/British pound = 1.432

First, you would convert the $2 million to euros at the 0.894 rate, giving you 1,788,000 euros. Next, you would take the 1,788,000 euros and convert them to pounds at the 1.276 rate, giving you 1,401,254 pounds. Next, you would take the pounds and convert them back to U.S. dollars at the 1.432 rate, giving you $2,006,596. Your total risk-free arbitrage profit would be $6,596.