31 CFR §306.105

1. (a)Timely notice. If prior to the time a registered security bearing an apparently valid assignment has been functioned, a claim is received from the owner or his authorized representative showing that:
   1. (1)The security was lost, stolen, or destroyed and that it was unassigned, or not so assigned as to have become in effect payable to bearer, or
   2. (2)The assignment was affected by fraud, the transaction for which the security was received will be suspended.
2. (b)Late notice. If, after a registered security has been transferred, exchanged, or redeemed in reliance on an apparently valid assignment, an owner notifies the Bureau that the assignment was affected by fraud or that the security had been lost or stolen, the Department will undertake only to furnish available information.
3. (c)Forged assignments. A claim that an assignment of a registered security is a forgery will be investigated. If it is established that the assignment was in fact forged and that the owner did not authorize or ratify it, or receive any benefit therefrom, the Department will recognize his ownership and grant appropriate relief.