ATM Shift

Key ATM Shift in Vanilla IRS refers to an optional number representing the shift that must be added on the currently valid at-the-money rate.
Note, this number is used only if Fxd_Rate is left unspecified.
For example, if equal to 0.01, during valuation the swap is considered to have a rate set to atm + 0.01, where atm equals the at-the-money rate determined dynamically according to the prevailing market at the time the valuation takes place.