The Dow Jones Industrial Average and the S&P 500 were pressured in early trades Friday as UnitedHealth (UNH) fell amid a Department of Justice probe. Blue chips were down 0.8%, or more than 350 points, while the S&P 500 traded 0.4% lower. The Nasdaq composite dipped 0.3% in the stock market today. Nvidia (NVDA) wavered ahead of earnings next week,…