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, in-the-money 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).