Answer: When short-term rates are negative, the financial analyst sets the rate to zero.

The correct answer is C. When short-term rates are negative, the financial analyst sets the rate to zero. This is because negative short-term interest rates can arise in models where the terminal distribution of interest rates follows a normal distribution. However, the existence of negative interest rates does not make much economic sense, as market participants would generally not lend cash at negative interest rates when they can hold cash and earn a zero return. To address the potential for negative interest rates when constructing interest rate trees, the analyst can set all negative interest rates to zero. This method localizes the change in assumptions to points in the distribution corresponding to negative interest rates and preserves the original rate tree for all other observations. Adjusting the risk-neutral probabilities or increasing the volatility would alter the dynamics across the entire range of interest rates and therefore not be an optimal approach. Despite the potential for negative rates, the model can still be desirable to use in certain situations, especially in cases where the valuation depends more on the average path of the interest rate, such as in valuing coupon bonds. Therefore, the potential for negative rates does not automatically rule out the use of the model.

Author: LeetQuiz Editorial Team