A portfolio that consists of short an ATM call with a 1 year maturity, a long ATM put with a 1 month maturity will be theta, assuming identical face values for both options This is because the theta of the 1 year option is the theta of the 1 month option positive negative neutral equal to greater than less thanAs timeto-expiry increases; the absolute value of gamma of a call option will : primarily due tel ',with all other inputs unchanged. increase decrease remain unchanged the impact at the squareroot of T the impact at the squarercpt of So the impact of sigma {the impact of the change in the present value of Se due to the change in T