U.S. stocks are starting the week lower on concerns continuing over tension in Ukraine and the Middle East. It is a light day on the earnings front. Halliburton (HAL) reported before the bell on Monday and is rising higher after its second quarter revenue topped Wall Street's expectations. Reynolds American (RAI) shares are lower after a Florida woman was awarded $23 billion for her husband's death from lung cancer. Yum! Brands (YUM) is also losing ground after saying it suspended orders from a Chinese meat supplier. Yum said this would affect some of its menu items. Blackberry (BBRY) named Marty Beard as its Chief Operating Officer. TheStreet's Susannah Lee reports from Wall Street.