By Kevin Matras

June 04, 2009

What a great name for a title! The delta I’m talking about though is the one that applies to options. And basically it’s a way to measure how much an option will increase or decrease in value based on the change in the underlying stock.

The definition of delta as it applies to options is: The percentage an option will increase or decrease in value in relation to the price movement of the underlying stock. For example, a delta of .60 or 60% means the option will move or change in value equal to 60% of the underlying stock’s price change, so a \$1.00 rise in the stock should see a 60-cent rise in the option premium. If the stock fell by -\$1.00, the option should decrease by -60 cents.

There’s a second part, though, to understand this fully. The delta will change (either increase or decrease), in general, based on how ‘in the money’ or ‘out of the money’ your option becomes.

For instance, let’s say there’s a stock trading at \$85 (like Amazon (AMZN – Snapshot Report) for example) and you had a \$95, out-of-the-money call option, with 4 months of time on it. That option might have a delta of .41 or 41%. Let’s also say that option was priced at 6.00 or \$600. Now let’s say the stock increased by \$10. This means that out-of-the-money call option with a delta of 41% would’ve increased by \$4.10 or \$410.

Now, that option is at-the-money. Remember, the option’s delta will increase or decrease based on how ‘in the money’ or ‘out of the money’ the option becomes. So now your option is at-the-money. Instead of your delta being 41%, it might now be 60%. If Amazon were to then increase another \$10, that option would now increase by another 60% (60% of the \$10 move) or \$6, i.e., \$600. And as the price goes up, and the more your option gets ‘in the money’, the bigger your delta will become until it gets to be 100%.

Likewise, the further ‘out of the money’ the option gets, the smaller the delta becomes. So when you’re deciding what option to buy or sell, look at the delta so you can get an idea as to how much your option will increase or decrease based on the underlying price of the stock.

In a future article, I’ll go over some techniques for choosing when its best to buy out-of-the-money options and when it’s best to buy in-the-money options. This will help balance your investment dollars while maximizing your gains and your delta and minimizing your risk.

But knowing your option’s delta is one of the keys to picking the right option to get into. You can learn more about different types of option strategies by downloading our free options booklet: 3 Smart Ways to Make Money with Options (Two of Which You Probably Never Heard About) available on Zacks.

Disclosure: Officers, directors and/or employees of Zacks Investment Research may own or have sold short securities and/or hold long and/or short positions in options that are mentioned in this material. An affiliated investment advisory firm may own or have sold short securities and/or hold long and/or short positions in options that are mentioned in this material.

Kevin Matras is the Research Wizard Product Manager and weekly contributing Editor at Zacks Investment Research who creates and writes the Zacks Commentary Screen of the Week and Know Your Options. For more information, visit http://www.zacks.com.