A floating-rate security is most likely to trade at a discount to its par value because the:'

Floating-rate securities are subject to interest rate risk because their coupon rates are not reset continuously. The longer the time until the security's next reset date, the greater its potential price fluctuation away from par value (to a discount or premium). Other reasons that the price can differ from par include caps and floors on the floating rate, changes in the issuers credit risk that are not reflected in the coupons quoted margin over LIBOR, and changes in the markets required margin for the firm’s level of credit risk. A decrease in the required margin would be likely to cause the security to trade at a premium rather than a discount. Liquidity risk is much less likely to change than default risk and market interest rates.