Gamma is another Options Trading Greek term, which determines the rate of change in option's delta with a 1-point move in the underlying asset. I.e., Gamma describes how Delta is expected to change with moves in the underlying (stock). Gamma is sometimes referred to as the 'speed' of the options contract or spread. Gamma decreases to 0 as the option contract becomes more 'stock-like' (delta approaching 1). Gamma also approaches 0 as the option gets further out-of-the-money (OTM). Gamma is at its peak and therefore the option's delta changes most rapidly when the option is at or near-the-money (ATM).