what is considered a fiduciary
A fiduciary is held to a standard of conduct and trust above that of a stranger or of a casual business person. He/she/it must avoid self-dealing or conflicts of interests in which the potential benefit to the fiduciary is in conflict with what is best for the person who trusts him/her/it.
Answer Wiki. A breach of fiduciary duty is, put simply, putting personal desires before the trust that has been placed in you. Typically, when a company executive or board places short-term gains over long-term consequences, there is a breach of fiduciary duty as their duty is to the company and its shareholders.