According to the Risk Structure of Interest Rates, Bonds with the same maturity have different YTM returns due to the following factors, EXCEPT: Differences in volatility of future interest rates. Differences in default risk. Differences in liquidity. Differences in tax treatment. The following are true statements about YTM returns on Bonds based on empirical observation and data available for the case of USA, EXCEPT to ross different types of bonds tend to follow the same long term