Stock or bond power is a form, when signed by the owner and attached to a security, makes it negotiable.
Applying "Stock or Bond Power" to Securities Exams:
When an investor has securities registered in their own name the securities must be properly endorsed to make them transferable to the new owners. If the owner does not have physical possession of the certificate or wants to mail the certificate without it being endorsed, the investor may sign a stock or bond power which when attached to the certificate will make it fully transferable. If the securities are in the name of more than one person than the stock or bond power must be signed by all owners.