Give a stream of consciousness and then the final answer. In the United States, a medallion signature guarantee is a special signature guarantee for the transfer of securities. It is a guarantee by the transferring financial institution that the signature is genuine and the financial institution accepts liability for any forgery. Signature guarantees protect shareholders by preventing unauthorized transfers and possible investor losses. They also limit the liability of the transfer agent who accepts the certificates. Not all MSG stamps are of equal value. A special coded prefix is given to each stamp, and this prefix determines how much monetary value can be guaranteed. For instance if the MSG is required for $400,000 worth of value, at least a C prefix is required, which is good for up to $500,000 value. If a D prefix stamp is submitted, the transaction will be rejected, because a D stamp is only good for guarantee up to $250,000. Often ComputerShare paperwork only informs of a need for a MSG, but does not specify anything about the necessity of certain prefixes.

Answer this question: when do you need a medallion signature guarantee?
The relevant information is: In the United States, a medallion signature guarantee is a special signature guarantee for the transfer of securities.
So, the final answer is for the transfer of securities.