However, since options are nonlinear derivatives, the delta itself will change with every move of the underlying asset;  i.e. the hedger must adjust the hedge amount dynamically, in order tocorrectly mimic the option to be replicated. Since in reality it is not possible to continuously adjust the hedge, the hedger is exposed to the risk of the delta changing quickly. The hedger with the delta position is always one step behind the true actual delta. The risk of unanticipated changes in the delta is called the gamma risk. In other words, the gamma is the sensitivity of the delta with respect to the underlying asset. If a trader wants to hedge gamma risk in addition to delta risk, he or she needs a security with a nonlinear payoff depending on the same underlying asset in addition to the underlying asset itself. By just using the underlying asset (which is an instrument with a linear payoff) the trader could never hedge gamma risk (which arises only in nonlinear payoffs). Similarly, option price sensitivities with respect to volatility (called vega), to interest rates (called rho) and to net yield can be calculated and used as a hedge measure for a change in the respective parameter. These sensitivities, which were developed for options on liquidly traded assets (e.g. equity), will generally be appropriate for property options as well.