The E1 visa is a form of non immigrant visa that is required by the US from traders of foreign countries who intend to conduct trade while in the US.
There are some reasons for E1 visa rejection such as failing to prove that you are a citizen of a country with whom the US government has signed a binding treaty; not belonging to a trading organization that has sufficient legal documents; insufficient evidence proving that you can initiate trade between your home country and the US during your US stay; and failing to prove you are an executive officer or supervisor in an eligible trade organization.
You are allowed to keep your E1 visa for as long as you are a qualified executive or supervisor of an eligible trading company. However, once you are removed from that position and become an ordinary worker (skilled or unskilled) you will no longer be eligible for an E1 visa. This is one of the major reasons for E1 visa rejection. You will hence be required to leave US soil once your E1 visa expires.
If the US government identifies that you acquired an E1 visa under fraudulent means, you will automatically be disqualified from holding such visa. This might be because you submitted the wrong information for your visa. People who are also mentioned as being ineligible to hold visas as described in the list of Non Immigrant Visa Applications may also find that as one of the more important reasons for E1 visa rejection.