A lawyer takes funds from a trust account that he oversees
An investment advisor redirects the investments of his clients
In these examples, the individual has a fiduciary responsibility to guard the assets placed in his care, and breaches that responsibility by stealing them.
Embezzlement is a criminal offense. However, many organizations simply fire employees found to have committed embezzlement, rather than prosecuting them. By doing so, employers hope to keep the matter quiet, so that outsiders are not aware of the lack of controls at the company.