undermining of trust

You'll have to put them into sentences before I can pass judgement. The isolated phrases themselves seem fine.

Hi,

Here is the context:

Anybody who gets involved in this kind of business practice endangers themselves because not only it is unethical and illegal but it can also greatly jeopardize reputation and financial status of the whole company.The influence on building good relationships with business partners can also be extremely unfavourable since serious breach of trust is in

Influence seems OK; another choice would be effect.

With regard to your first question, among serious undermining/betrayal of trust/confidence or breach of trust-- all would work, I think. However, to me breach has an official, legal ring to it that the others do not.

thanks Mr Micawber