Put-Call Parity states that for European options on a non-dividend-paying stock:
C − P = S − PV(K) = S − Ke-rT
If this relationship is violated, a riskless arbitrage profit exists.
Synthetic Positions
Put-call parity allows creating synthetic positions:
- Synthetic Long Call: Long put + Long underlying
- Synthetic Long Put: Long call + Short underlying
- Synthetic Long Stock: Long call + Short put (same strike)
- Synthetic Forward: Long call + Short put = long futures (approximately)