GammaA measure of the rate of change in an option's Delta for a one-unit change in the price of the underlying stock. See also
Delta.
GEMNasdaq GEMX, LLC
Good-'til-cancelled (GTC) orderA type of limit order that remains in effect until it is either executed (filled) or cancelled. This is unlike a day order, which expires if not executed by the end of the trading day. If not executed, a GTC option order is automatically cancelled at the option's expiration.