The delta of a call option (call) is positive, and the delta of a put option (put) is negative. Consider a hypothetical example in which you hold calls with a delta of 0.3 on 1,000 units of the underlying asset. When the price of the underlying asset rises by 1 yen, the value of the options rises by about 300 yen. If you have sold 300 units of the underlying asset, the profit or loss on the options and on the short position in the underlying asset roughly offset each other when the price moves a little up or down. In the currency option market, the option to trade is specified by delta instead of strike, as in "a 25-delta call."