One of the largest losses in history from unauthorized securities trading involved a securities trader for the French bank Societe Generale. The trader was able to circumvent internal controls and create more than $7 billion in trading losses in six months. The trader apparently escaped detection by using knowledge of the bank's internal control systems learned from a previous back-office monitoring job. Much of this monitoring involved the use of software to monitor trades. In addition, traders were usually kept to tight trading limits. Apparently, these controls failed in this case

What general weaknesses in Societe Generale's internal controls contributed to the occurrence and size of the losses?