Stephen Hemsley became executive chairman, UnitedHealth Group, on September 1, 2017. In this position, Hemsley remains actively involved in supporting the senior management team, oversight of planning and performance and helping guide the enterprise. As chairman of the board of directors, he leads the strategic responsibilities of the board. Hemsley was formerly chief executive officer, UnitedHealth Group, from 2006 to 2017. He has been a member of the company's board of directors since 2006. He previously served as president and chief operating officer, UnitedHealth Group. Hemsley joined the company in June 1997.
David Wichmann became chief executive officer, UnitedHealth Group, on September 1, 2017. He is responsible for the strategic direction and overall performance of the enterprise and its long-term growth agenda. He is also a member of the board of directors. Previously, Wichmann served as president, UnitedHealth Group, beginning in November 2014, with oversight responsibility for all of UnitedHealthcare's domestic and international businesses, and for overall UnitedHealth Group performance. Wichmann also served as chief financial officer of the enterprise from 2011 until mid-2016. He previously held positions as president, UnitedHealthcare; president and chief executive officer, Specialized Care Services (now OptumHealth); and senior vice president, Corporate Development. Prior to joining UnitedHealth Group in 1998, Wichmann was a partner with Arthur Andersen.
Dirk McMahon was named president and chief operating officer, Optum, in April 2017, with responsibility for driving Optum's enterprise performance overall and directly overseeing OptumInsight, Optum Technology, Operations, Optum Administration and business and corporate strategy. He also was named to the Office of the Chief Executive. Previously, he was executive vice president, Enterprise Operations, UnitedHealth Group. McMahon has served in a number of leadership positions across the enterprise since joining the company in 2003, including chief executive officer, OptumRx, overseeing UnitedHealth Group's pharmacy benefit management programs, along with various management positions in information technology, operations and finance. He also served as president and CEO, UnitedHealthcare Benefit Operations. Before joining UnitedHealth Group, McMahon was head of airport operations worldwide for Northwest Airlines.
Steve Nelson has served as executive vice president, UnitedHealth Group, and chief executive officer, UnitedHealthcare, since August 2017. He also was named to the Office of the Chief Executive. Nelson previously served as chief executive officer, UnitedHealthcare Medicare & Retirement, from 2014 to 2017. Earlier roles included leadership of UnitedHealthcare Community & State and UnitedHealthcare Employer & Individual's West Region. Before joining UnitedHealthcare, Nelson was president of the Eastern Region and Senior Products Division at HealthNet from 2004 to 2007. Nelson also served for 10 years in various executive roles at the Henry Ford Health System and Intermountain Healthcare.
Larry Renfro was named vice chairman, UnitedHealth Group, in November 2014, with oversight responsibility for all enterprise strategic relationships, key client relationships and companywide business growth efforts, and appointed to the Office of the Chief Executive. Renfro also is managing partner of Optum Ventures investment funds, helping accelerate innovation at Optum and across the enterprise through early stage investments in emerging and advanced technology, data and analytics and health care services companies with transformative capabilities. Renfro joined the company in January 2009 and has served as chief executive officer, Optum, and CEO, Public and Senior Markets Group. He was formerly a senior executive officer at Fidelity Investments and a member of the Fidelity Executive Committee. Renfro was president and chief executive officer, AARP Services, Inc., before he rejoined Fidelity in 2008. Renfro has also held senior executive positions at NewRiver, Inc.; State Street Bank & Trust; and Allmerica Financial.
John Rex was appointed executive vice president and chief financial officer, UnitedHealth Group, and a member of the Office of the Chief Executive in 2016. Previously, Rex served as executive vice president, chief financial officer, Optum, UnitedHealth Group's health services platform, joining the company in 2012. Prior to Optum, Rex was a leading equity research analyst in the health care sector and managing director, J.P. Morgan. He also worked as a strategy and operations consultant, specializing in health services. A certified public accountant, Rex advised clients for Ernst & Young, where he also specialized in the health services sector.
Dan Schumacher is president and chief operating officer, UnitedHealthcare, and was named to the Office of the Chief Executive for UnitedHealth Group in September 2017. Schumacher has oversight responsibility for U.S. and global commercial markets including the Employer & Individual business. Additionally, he leads the clinical, network, operations and technology groups for all of UnitedHealthcare's domestic teams. Prior to this role, Schumacher served as chief financial officer and controller, UnitedHealthcare. Previously, he served as chief financial officer, Group Insurance Division, Specialized Care Services (now OptumHealth); director of Finance, Specialized Care Services, and director, UnitedHealth Group Corporate Development, in enterprisewide merger and acquisition activity.
Marianne Short was appointed executive vice president and chief legal officer, UnitedHealth Group, in January 2013, and was named to the Office of the Chief Executive in November 2014. She is responsible for overseeing legal, regulatory and compliance matters across the enterprise. Prior to joining the company, Short was the managing partner at Dorsey & Whitney LLP for six years, a partner in the Trial department, co-chair of the firm's Appellate and Health Litigation practice groups and a member of the American College of Trial Lawyers and the American Academy of Appellate Lawyers. From 1988-2000, she was a judge on the Minnesota Court of Appeals, authoring more than 900 opinions in virtually every area of civil and criminal law. She has more than 35 years of courtroom experience from her work on the court, the Dorsey firm and the Minnesota Attorney General's Office.
Ellen Wilson was appointed executive vice president, Human Capital, UnitedHealth Group, in June 2013, and was named to the Office of the Chief Executive in November 2014. She is responsible for overseeing all aspects of human resources, including compensation and benefits, talent management, leadership and employee development, rewards and recognition and organization development. Previously, Wilson served as chief administrative officer, Optum, guiding Optum's mission-critical business alignment and cultural programs. Prior to joining Optum, she served for 17 years at Fidelity Investments, concluding her tenure there as head of Human Resources.
Andrew Witty is chief executive officer of Optum, a global health services leader and part of UnitedHealth Group. He was named CEO and joined the Office of the Chief Executive in 2018, after serving as a UnitedHealth Group company director. Witty served as chief executive officer and a director of leading pharmaceutical manufacturer GlaxoSmithKline (GSK) from 2008 to 2017. He joined GSK in 1985, and prior to being named CEO served as president of GSK Europe. Before that, he held a variety of international leadership roles for GSK in markets including Asia-Pacific. Witty is former chancellor of the University of Nottingham, a British public research university, and serves on the Singapore Economic Development Board International Advisory Committee. He is an advisor to 8VC and Hatteras Venture Partners, as well as to the Bill and Melinda Gates Foundation. Witty was knighted in 2012 for services to the U.K. economy. In 2017, he was named an Honorary Citizen by Singapore for his contributions to the country's growth and development.
Cory Alexander joined UnitedHealth Group in 2009 and oversees a number of key functions across the enterprise: government and public affairs, international relations, United Health Foundation and social responsibility efforts, the Center for Health Reform and Modernization, and enterprise government solutions and strategic relationships development. From 2006 to 2008, Alexander was vice president, Government and Industry Relations, Fannie Mae, and previously worked as chief of staff for House Democratic Whip Steny Hoyer (D-MD).
Terry Clark was appointed senior vice president and chief marketing officer, UnitedHealth Group, in 2014. Clark oversees branding, marketing and advertising for UnitedHealth Group and its two operating platforms, UnitedHealthcare and Optum, with responsibility for helping positively shape the customer experience. Previously, Clark served as chief marketing officer, UnitedHealthcare Medicare & Retirement, where he led marketing and direct-to-consumer engagement efforts focused on seniors. Clark joined UnitedHealthcare in 2006 from InterActiveCorp, a consumer technology company comprised of leading digital brands, where he served as executive vice president, sales and marketing, for the Entertainment Publications division.
In 2013, Richard Migliori, M.D. was appointed executive vice president, Medical Affairs, and chief medical officer, UnitedHealth Group, working with businesses across the enterprise to help improve health care quality, access and affordability. Previously, as executive vice president, Health Services, Dr. Migliori was responsible for the ongoing development, design, and adaptation of market leading clinical innovations aimed at ensuring clinical excellence, improving clinical and economic outcomes, and delivering robust business performance on behalf of UnitedHealth Group's largest public and private sector clients.
Don Nathan joined UnitedHealth Group as senior vice president, chief communications officer, effective May 2007. He is responsible for all internal and external communications. Nathan was formerly a strategic communications consultant with Robinson Lerer & Montgomery, beginning in 1991, and was a partner at the firm for 10 years. Previously, Nathan worked on Capitol Hill in Washington, D.C., serving in a number of congressional and campaign capacities.
John Penshorn, senior vice president, has managed UnitedHealth Group's capital markets relationships since December 1998. Previously, Penshorn followed health services equities as a stock analyst at Piper Jaffray.
Tom Roos was appointed chief accounting officer for the enterprise in August 2015. He is responsible for SEC reporting, accounting policy, tax and enterprise risk management. Previously, Roos was a partner at Deloitte & Touche LLP for eight years, where he worked closely with Deloitte & Touche's national office and industry leaders on emerging technical accounting and reporting matters in the health insurance industry, with experience in company mergers and acquisitions and initial public offerings.