The stock could be set to rebound after a pricing misstep has hurt its results this year. UnitedHealth Group (UNH -1.53%) has run into a very difficult stretch, with the stock price cut nearly in half over the past year. However, a few well-known investors scooped up shares of the stock in the second quarter, including Warren Buffett's Berkshire Hathaway (BRK.A 1.28%) (BRK.B 1.35%). first is its mix in enrollment, as new members who were previously underserved have more complex issues than expected. Second, ...