U.S. stocks are falling in morning trading Friday, following other markets around the world lower. Some investors are concerned that stocks may have gotten ahead of themselves after the best week for the S&P 500 in eight months. Stocks rallied sharply through the first four days of this week and had erased all their earlier losses from worries about a new virus from China that’s rapidly spreading. Energy stocks had some of Friday’s sharpest losses as the price of oil fell again. Bond prices rose. The yield on the 10-year Treasury fell to 1.58%.