UnitedHealth Group named a new chief financial officer Friday as part a broader shift among top executives.

John Rex, formerly the CFO at United's fast-growing health services division Optum, is succeeding David Wichmann, who will now focus on his duties as the company's president, the Minnetonka-based health insurer announced Friday.

Rex, 54, will have oversight responsibilities for the company's treasury and investment activity as well as mergers and acquisitions. Before joining Optum, he worked in the financial services industry including a recent job as a managing director at J.P. Morgan.

Rex will receive a base salary of $800,000 and will be eligible for an annual cash incentive award with a target value of 115 percent of his base pay, according to a regulatory filing. He also received equity awards with a fair value of $2.5 million in connection with the appointment.

All terms of Wichmann's employment, including compensation, are unchanged, the company said.

Rex is being succeeded as Optum's chief financial officer by Tami Reller, who is currently the chief marketing officer at Optum. Before working for Optum, Reller worked at Microsoft and Great Plains Software.

In a statement, Wichmann said the moves show the "deep bench of our leadership team."

UnitedHealth Group operates Optum as well as its UnitedHealthcare business, which is the nation's largest health insurer. The company is the largest publicly traded firm in Minnesota, with more than 200,000 workers worldwide including more than 14,000 in the Twin Cities.

United last announced a reshuffling near the top in November 2014 with the departure of Executive Vice President Gail Boudreaux. The company at the time also created a five-member "Office of the Chief Executive," which Rex will now join.

In the regulatory filing on Friday, United also noted that CEO Stephen Hemsley and the company agreed to amend his supplemental executive retirement pay, the value of which has remained unchanged since 2006. The $10.7 million lump sum is being converted into 78,789 deferred stock units, which will entitle Hemsley to equivalent of dividends in the form of additional deferred stock units.

UnitedHealth shares closed at $139.24 Friday, down $1.44 on the day. Shares are up about 8 percent since the beginning of the year.

Christopher Snowbeck • 612-673-4744

Twitter: @chrissnowbeck