What is an underking?

Excuse me, could you please clarify what you mean by "underking"? Is it a term specific to a particular industry or field? If it's related to cryptocurrency or finance, I'm not immediately familiar with the term. Could you provide some context or explain what you're referring to? It's possible that "underking" is a niche term or a colloquialism that I haven't come across in my professional practice. Understanding the context would help me give you a more accurate and relevant answer.