Wall Street shares closed lower on Thursday trading session snapping their streak of gains lasting for six straight days as drop of AT&T and biotech shares overshadowed increase of Boeing and Gilead. The Standard & Poor's 500 Index slipped 0.22% to 1,875.39, the Nasdaq Composite Index fell 0.83% to 4,126.967 and the Dow Jones industrial average tumbled 0.08% to 16,501.65.