Think of them as "place holders"; they can't be trade/sold. Depending on your broker, they will be listed as different things. The value of these "place holders" are dependent on available funds in the liquidating trust after first priority beneficiaries are paid (in accordance with the Liquidating Trust Agreement).
You will see in conversations here that refer to potential value of these "place holders" as the following escrow, LTI, LTI Distributions, WMI Liquidating Trust, etc.