Explanation

When the embedded put option in a putable bond is out of the money, the bond behaves similarly to an option-free bond. This is because:

• Out of the money put option: The strike price (put price) is below the current market price, making it unattractive for the bondholder to exercise the put option
• Effective duration similarity: The bond's price sensitivity to interest rate changes is similar to that of an option-free bond
• Insensitivity to small yield shifts: Small changes in yields don't significantly affect the probability of the put option being exercised

If the put option were in the money or at the money, the bond's duration would differ from an option-free bond due to the higher probability of the put option being exercised, which would affect the bond's price sensitivity to interest rate changes.