It stands for deep in the money; an option is said to be deep in the money when its exercise price is significantly below (for a call option) or above (for a put option) the market price of the underlying asset. Significantly, below/above is considered one strike price below/above the market price of the underlying asset. For example, if the current price of the underlying stock was $10, a call option with a strike price of $5 would be considered deep in the money.

The most important characteristic of this type of option is its considerable intrinsic value, which is calculated by subtracting the strike price from the underlying asset’s market price for a call option (and vice versa for a put option). As an option moves deeper into the money, the delta approaches 100% (for call options), which means for every point change in the underlying asset’s price, there will be an equal and simultaneous change in the price of the option, in the same direction. Thus, investing in the option is similar to investing in the underlying asset, except the option holder will have the benefits of lower capital outlay, limited risk, leverage and greater profit potential.