Credit risk, interest-rate risk, duration and liquidity in debt schemes.
Debt schemes invest primarily in fixed-income and money-market instruments. Their risks are different from equity risk: interest-rate sensitivity, credit/default risk, liquidity and reinvestment conditions can matter.
Duration helps explain sensitivity to changes in yields. Credit quality helps explain the potential for default or spread-related losses. A short-duration or liquid portfolio can still have risks; “debt” does not mean “guaranteed.”
For short liabilities, the first test is whether the instrument's risk and liquidity match the timing of the liability.