I think bonds are debt/loan and fixed-income, so they are risk-free, both short term and long term. But it seems like Bodie's Investment thinks long-term bonds are risky:
For example, assume that the total market value of an initial portfolio is $300,000, of which $90,000 is invested in the Ready Asset money market fund, a risk-free asset for practical purposes. The remaining $210,000 is invested in risky securities--$113,400 in equities (E) and $96,600 in long-term bonds (B). The equities and long bond holdings comprise "the" risky portfolio, 54% in E and 46% in B.
Why are long-term bonds risky?
Are short-term bonds risky or riskless? Thanks!