Answer:
Discretionary authority is an important thing to be aware of when dealing with a broker because it allows a broker to make a trade or buy stocks on your behalf without you been present.
The broker's aim will be to make excess profit from the deal done because he or she is making the deal without you being present. After the deals might have been sealed the broker will be paid is interest. At that stage, he/she has the opportunity to create a recurrence transaction paying no attention to what is to your greatest advantage. The more trades he/she makes, the more cash he/she makes