The largest operating cost center for airlines, on average, are the companies' fuel expenses and those expenses related to the procurement of oil.

When oil prices are increasing in the global economy, it's natural that the stock prices of airlines drop. When oil prices decline in the economy, it's equally natural that the stock prices of airlines go up. Fuel costs are such a large part of an airline's overhead percentage-wise that the fluctuating price of oil greatly affects the airline's bottom line.

To protect themselves from volatile oil costs, and sometimes to even take advantage of the situation, airlines commonly practice fuel hedging. They do this by buying or selling the expected future price of oil through a range of investment products, protecting the airline companies against rising prices.

Purchasing Current Oil Contracts

In this hedging scenario, an airline would have to believe that prices will rise in the future. To mitigate these rising prices, the airline purchases large amounts of current oil contracts for its future needs.

This is similar to a person who knows that the price of gas will increase over the next 12 months and that he will need 100 gallons of gas for his car over the next 12 months. Instead of buying gas as needed, he decides to purchase all 100 gallons at the current price, which he expects to be lower than the gas prices in the future.

Purchasing Call Options

When a company purchases a call option, it allows the company to purchase a stock or commodity at a specific price within a certain date range. This means that airline companies are able to hedge against rising fuel prices by buying the right to purchase oil in the future at a price that is agreed on today.

For example, if the current price per barrel is $100, but an airline company believes that the prices will increase, that airline company can purchase a call option for $5 that gives it the right to purchase a barrel of oil for $110 within a 120-day period. If the price per barrel of oil increases to above $115 within 120 days, the airline will end up saving money.

Implementing a Collar Hedge

Similar to a call option strategy, airlines can also implement a collar hedge, which requires a company to purchase both a call option and a put option. Where a call option allows an investor to purchase a stock or commodity at a future date for a price that's agreed upon today, a put option allows an investor to do the opposite: sell a stock or commodity at a future date for a price that's agreed on today.

A collar hedge uses a put option to protect an airline from a decline in the price of oil if that airline expects oil prices to increase. In the example above, if fuel prices increase, the airline would lose $5 per call option contract. A collar hedge protects the airline against this loss.

Purchasing Swap Contracts

Finally, an airline can implement a swap strategy to hedge against the potential of rising fuel costs. A swap is similar to a call option, but with more stringent guidelines. While a call option gives an airline the right to purchase oil in the future at a certain price, it doesn't require the company to do so.

A swap, on the other hand, locks in the purchase of oil at a future price at a specified date. If fuel prices decline instead, the airline company has the potential to lose much more than it would with a call option strategy.