An at-the-money option (call option) in which the strike price is equivalent or approximately equal to the underlying asset’s price. There is little or no intrinsic value in ATM calls. In other words, this option would generate zero cashflow if it were exercised in its current moneyness state. For instance, if XYZ stock is currently (in February) trading at $55, then the March $55 call would be at-the-money.

A call on an index would be at-the-money when the current index value equals the strike price. For example, an index call with strike price of 1,000 would be at-the-money when the index is currently trading at 1,000.