# Tag Info

Call-put parity writes (to see this, notice that $(S_T-K)^+ - (K-S_T)^+ = S_T - K$ and take the discounted risk-neutral expectation $E^{\mathbb {Q}} [. \vert \mathcal {F}_0 ]$ on both sides): $$C(K,T) - P(K,T) = DF ( F(0,T) - K )$$ with $DF = e^{-rT}$ the discount factor, and $F(0,T)$ the fair forward price given by $$F(0,T) = (S_0 - D^*)e^{rT}$$ ...