Definition
Put-call parity states that for European options with the same underlying, strike (K), and expiry, the call price (C) minus the put price (P) equals the current stock price (S) minus the present value of the strike price discounted at the risk-free rate over the option's life. Rearranged: C + PV(K) = P + S. If parity breaks, a riskless arbitrage exists - for example, if the call is overpriced relative to the put, a trader can sell the call, buy the put, buy the stock, and borrow PV(K) to lock in a profit with no net investment. In practice, dividends and early-exercise features of American options create small deviations from the parity formula, but arbitrageurs keep prices tightly aligned. For the CIRE, put-call parity is tested as a conceptual check: given three of the four variables (C, P, S, K), solve for the fourth, or identify which option is relatively over- or underpriced.
Source
Options theory; verify specific formula emphasis in CIRE blueprint; Montreal Exchange educational resources
Where this shows up on the CIRE
- Outcome 5.3