My understanding of Delta is the on the CALL side, if the delta is 0.40, for every $1.00 move up in underlying price the option price will go up by 0.40. What happens if the underlying moves down by $1.00, will the option price also move down accorindingly by 0.40? Also, for the PUT side, assuming delta is -0.30, what happens when the underlying moves down by $1.00? I had assume that this will cause the option price to be reduced by 0.30. Correct me if I'm wrong. Thanks!