Reinvestment risk is the risk that if rates fall, cash flows will be reinvested at lower rates, resulting in a holding return lower than that expected at purchase.
Prepayment risk (and call risk) is the risk that the issuer will repay principal prior to maturity. Prepayments are most likely to occur in a declining interest rate environment because it is cheaper to issue replacement debt. Event risk means that the issuer could face a single event or circumstance that would affect its ability to service/repay the debt. For example, a corporation could suffer an industrial accident.
