[4][6][7] In the 1980s, Neidorff was the director of international consumer products at Miles Laboratories, and worked as president and chief executive officer of Physicians Health Plan of Greater St.

[11] In 2018, Neidorff was one of the executives named in a lawsuit claiming that Centene failed to disclose Health Net's potential tax exposure prior to their acquisition.

[12] In April 2020, Neidorff joined the White House economic recovery task force on reopening the United States after the COVID-19 pandemic.

[17] In 2017, the Saint Louis Dispatch named Neidorff the Citizen of the Year, after he spearheaded the opening of a Centene office in Ferguson, Missouri in 2016.

[21][22] Neidorff and his wife Noémi, the former board chair of the Opera Theatre of St. Louis, were patrons to the arts and supported many music and educational organizations in Missouri and elsewhere.