A more thorough explanation:

A stock power is a legal document that allows someone other than the owner of a security to transfer ownership of that security to a third party. It is also known as a stock/bond power.

For example, if John wants to transfer ownership of his stocks to his daughter, but he is unable to do so himself, he can use a stock power to give his daughter the authority to transfer the stocks to her name.

Another example is when a person passes away and their stocks need to be transferred to their heirs. The executor of the estate can use a stock power to transfer the ownership of the stocks to the heirs.

Overall, a stock power is a useful tool for transferring ownership of securities when the owner is unable to do so themselves.