Can Put-Call Parity Be Applied to American-Style Options?

The standard put-call parity formula cannot be applied directly to American-style options because of the possibility of early exercise. However, boundary conditions and inequalities based on the parity relationship can be established.

These inequalities provide a range within which the prices of American calls and puts must trade to prevent arbitrage, though they do not provide a single, exact pricing relationship like the European parity formula.