Most people probably think about banks as a service to the other economic actors, but this is only part of the story.

Banks have engaged in trading activities for 'their own account' and have earned substantial profits from this activity.

The profit earned through proprietary trading is good for the stockholders of the bank, but it raises a lot of questions about the ability of a bank to give objective advice to its clients when the bank has taken positions in the market that might giove rise to conflict of interest.