The situation in which the strike of an option is set equal to the spot rate (e.g., FX rate) at which the option delta is hedged. In general option moneyness can defined with respect to either the spot price (ATM spot) or the forward price (at expiration, and hence there is an ATM forward). In the case of an ATM spot, the option’s expiration date is irrelevant in determining the strike. ATM options are typically quoted ATM spot.
This is also known for short as ATMS.
