UnitedHealth Group Inc. signage on the floor of the New York Stock Exchange on April 21, 2025.The health care stock popped 12% in morning trading, on track for its best day in five years. UnitedHealth, often viewed as the industry's bellwether, is set to add about 209 points to the Dow Jones Industrial Average at Friday's open.Shares of UnitedHealth were down nearly 50% for 2025 through Thursday's close before Buffett's filing. The largest private health insurer has become the face of public blowback in thi ...