Let C (K ) denote a European vanilla Call option with strike price K . Assume that all options are identical except for strike price, and strike prices satisfy K < K < K and 2K = K K+.
??Question 1 [5 marks]
What are the no-arbitrage lower bound, and the no-arbitrage upper bound, of the vertical spread
C(K1)-C(K2 )?
Question 2 [10 marks]
Derive the functional relationship between the no-arbitrage values of the two vertical spreads, C(K1)-C(K2)and C(K2)-C(K3).