Meet Our Leaders

Sir Andrew Witty was named chief executive officer of UnitedHealth Group in February 2021. As UnitedHealth Group CEO, Sir Andrew 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 UnitedHealth Group board of directors. Witty was named executive vice president of UnitedHealth Group, and chief executive officer of Optum, in March 2018 and previously served as a UnitedHealth Group company director. From 2008 to 2017, Witty was chief executive officer and a director of the leading pharmaceutical manufacturer GlaxoSmithKline plc (GSK). He joined GSK in 1985, and prior to being named CEO, served as president of GSK Europe. Witty is former chancellor of the University of Nottingham, a British public research university, and serves on the Singapore Prime Minister’s Research, Innovation and Enterprise Council. Witty became chair, Imperial College Business School Advisory Board, in November 2020. Between April and December 2020 Witty took an unpaid leave as special envoy at the World Health Organization, co-leading the effort to accelerate responses to COVID-19. 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. He holds honorary degrees from Exeter, Manchester and Nottingham Universities.

John Rex was appointed executive vice president and chief financial officer, UnitedHealth Group, in 2016. In 2012, Rex joined Optum, UnitedHealth Group’s health services business, as executive vice president, chief financial officer. In his prior roles, Rex was a leading equity research analyst, served as a strategy and operational consultant and practiced as a certified public accountant across diverse health care sectors.

Dirk McMahon was named president and chief operating officer, UnitedHealth Group, in February 2021. He was named chief executive officer, UnitedHealthcare, in June 2019. Prior to this role, McMahon was president and chief operating officer, Optum, with responsibility for driving Optum's enterprise performance overall and directly overseeing OptumInsight, Optum Technology, Operations, Optum Administration and business and corporate strategy. In 2017, McMahon 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. Before joining UnitedHealth Group, McMahon was head of airport operations worldwide for Northwest Airlines.

Cory Alexander serves as a strategic advisor for UnitedHealth Group, where he provides advice and perspective on the company’s external, societal and political environment with a particular focus on long-term evolution in the health care landscape. Previously, Alexander was executive vice president for Corporate Affairs. In this role, he provided executive leadership for marketing, communications, research, international relations, U.S. external affairs, social responsibility and United Health Foundation activities. From 2014 to 2018, Alexander led External Affairs, with responsibility for enterprise government and public affairs, international relations, and social responsibility activities. Alexander joined UnitedHealth Group in 2009, serving in various Government Affairs leadership roles. Prior to joining UnitedHealth Group, Alexander held a senior role in Government Relations for Fannie Mae and previously served 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.

Patricia Lewis was appointed executive vice president and chief human resources officer, UnitedHealth Group, in 2019. She is responsible for overseeing all aspects of human capital, including compensation and benefits, talent management, leadership and employee development, rewards and recognition and organization development. Lewis joins UnitedHealth Group from Lockheed Martin, where she was senior vice president and chief human resources officer, leading a large global team to deploy a human capital strategy in support of a diverse global workforce in more than 50 countries. She has successfully led human capital teams within complex and highly regulated industries spanning aerospace, defense, energy, cybersecurity, data analytics, biometrics, technology and chemicals. Prior to joining Lockheed Martin in 2011, Lewis held various positions in Human Resources at IBM and DuPont.

Brett Manderfeld was named senior vice president for UnitedHealth Group’s Capital Markets Communications area in June 2019. Manderfeld joined the company’s Capital Markets Communications area as vice president in May 2007. Previously, he served as a senior stock analyst at Piper Jaffray following technology and business service companies.

Richard Mattera was named chief development officer of UnitedHealth Group in 2020. He leads corporate development efforts enterprisewide, with responsibility for both legal and financial oversight, as well as strategic integration plan development, performance and measurement, fostering continued expansion of established and emerging businesses directly aligned with the social mission and growth strategy of the company. Previously, Mattera was the chief legal officer at Optum and has led the M&A legal function across UnitedHealth Group for nearly a decade. Prior to joining UnitedHealth Group in 2011, Mattera was a partner at the international law firm of Hogan Lovells, where he represented publicly and privately held companies in a variety of matters, including in the areas of mergers and acquisitions, joint ventures, securities, corporate finance and corporate governance.

Richard Migliori, M.D., serves as executive vice president and senior advisor at UnitedHealth Group, where he is focused on strategic initiatives that accelerate the company’s growth priorities, and advancing client partnerships. He retired in 2021 from his position as executive vice president of Medical Affairs and chief medical officer of UnitedHealth Group. In that role he worked 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.

Larry Renfro was named vice chairman, UnitedHealth Group, in November 2014. Renfro has oversight responsibility for all enterprise strategic relationships, key client relationships and companywide business growth efforts. He 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.

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.

Dan Schumacher was named chief strategy and growth officer for UnitedHealth Group in April 2021. In this role, he is responsible for efforts focused on experience, strategic client relationships, research and development, growth and transformation. Previously, Schumacher served as president and chief operating officer of Optum where he was responsible for driving Optum enterprise performance and oversight of OptumInsight, as well as Optum Technology, global operations and enterprise clinical capabilities. Prior to his role at Optum, he served as president and chief operating officer of UnitedHealthcare where he had direct oversight responsibility for U.S. and global commercial markets including the UnitedHealthcare Employer & Individual business and the clinical, network, operations and technology groups for all of UnitedHealthcare's domestic teams. Schumacher also served as chief operating officer and chief financial officer at UnitedHealthcare and co-led UnitedHealthcare alongside the three UnitedHealthcare principal business leaders. He also 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 serves as executive vice president, UnitedHealth Group, focusing on strategic enterprise initiatives. Previously, Short served as executive vice president and chief legal officer, UnitedHealth Group, where she was responsible for overseeing legal, regulatory and compliance matters across the enterprise from January 2013 until January 2021. 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 serves as executive vice president, UnitedHealth Group, focusing on strategic enterprise initiatives. Previously, Wilson served as executive vice president and chief human resources officer, UnitedHealth Group, where she oversaw all aspects of human resources from June 2013 until November 2019. Prior to joining UnitedHealth Group she served for 17 years at Fidelity Investments, concluding her tenure there as head of Human Resources. Wilson earned a Bachelor of Science in Business Administration from Bryant University and a Master in Business Administration from Babson College. She currently serves on the board of the Walker Art Center, Boston Ballet and Bryant University.