The combination of buying a put option and selling a call option at the same strike price is equivalent to selling ¥15 billion forward at a forward rate equal to the strike price on the put and call options. That is, Bechtel is no longer holding an option; it is now holding a forward contract. If the yen appreciates and Bechtel loses its bid, it will face an exchange loss equal to 15 billion x (actual spot rate - exercise price).