Who is APM owned by?

Could you please clarify who the owner of APM is? I'm curious to know if APM is a privately held company, a publicly traded entity, or perhaps part of a larger financial group. Additionally, I'd be interested in understanding the company's ownership structure and any potential shareholders or investors that may have a significant stake in APM. Could you provide any insights into the background and history of APM's ownership, as well as any changes or developments that have occurred over time?