It is not legal for your broker to sell securities from your account without your permission. Brokers and advisors are required to have the express permission of an investor to process a transaction. If you feel a trade or sale was made in violation of your agreement terms, you can follow up with the brokerage firm manager or file a complaint with the Securities and Exchange Commission. 

A trading authorization can be signed for a discretionary account. Such a document is viewed as a limited power of attorney and allows a broker to sell securities from an account without gaining permission for each transaction. Trades made under such an account are limited. They are to follow guidelines created by calculating your risk tolerance and investment goals; these should be described in your contract with the broker.

Brokers may attempt to seek permission after the fact using various excuses. If you allow this to happen once, the broker may view this as permission on your part, and proof that you condone similar trades. It may adversely affect your case if you agree with the broker that actions taken without your permission were in your best interest. Trades are not authorized if the client fails to understand a trade will be made or the client gave no permission for a transaction. You may wish to state for the record that you do not agree to any trades made without your permission (even if you made a profit by the action).

Margin accounts fall under a slightly different set of rules because your account must maintain a certain equity level. If it should fall below that level, the brokerage firm may sell your securities without notifying you, without your permission, under the terms of the account. The sale of your securities under such circumstances can impact your account quite negatively, and investors should have a thorough understanding of their margin account agreement. For more information, see:

--  Unauthorized Trading:

        www.stockbroker-fraud.com/lawyer-attorney-1247305.html

--  Types of Stock Broker Misconduct:

        www.usinvestorlaw.com/types-of-stock-broker-misconduct.php

--  U.S. Securities and Exchange Commission tips on brokers:

         www.sec.gov/investor/brokers.htm