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The ratio of the change in price of an option to the change in price of the underlying
asset. Also called the hedge ratio
. Applies to derivative products. For a call option
on a stock, a delta of 0.50 means that for every $1.00 that the stock goes up, the option price rises by $0.50. As options near expiration
call option contracts approach a delta
of 1.0, while in-the-money put options
approach a delta of -1. See: hedge ratio
, neutral hedge
. Call deltas range from 0.00 to +1.00; put deltas range from 0.00 to -1.00. If the call delta is 0.69, the put delta is -0.31 (call delta minus 1 equals put delta; 0.69 -1 =-0.31).
The change in the price of an option that results from a one-point change in the price of the underlying stock. For example, a delta of 0.5 indicates that the option will rise in price by 1/2 point (50¢) for each 1-point ($1) rise in the price of the underlying stock. Call options have positive deltas; put options have negative deltas.
The relationship between an option's price and the price of the underlying stock or futures contract is called its delta.
If the delta is 1, for example, the relationship of the prices is 1 to 1. That means there's a $1 change in the option price for every $1 change in the price of the underlying instrument.
With a call option, an increase in the price of an underlying instrument typically results in an increase in the price of the option. An increase in a put option's price is usually triggered by a decrease in the price of the underlying instrument, since investors buy put options expecting its price to fall.