From: Charles Koch
Subject: David Koch's retirement

In October 2016, David announced that, "Over the summer I was hospitalized and I am now suffering from declining health ..." Unfortunately, these issues have not been resolved and his health has continued to deteriorate. As a result, he is unable to be involved in business and other organizational activities. Because of this, David will be retiring from his responsibilities at Koch and other organizations.

https://www.cnbc.com/2018/06/05/billionaire-david-koch-to-retire-from-koch-industries-political-group.html