stock indexes were posting strong gains after the opening bell thursday as investors cheered earnings from electricvehicle maker tesla inc tsla and upbeat updates from airlines and other corporate results the dow jones industrial average djia advanced 230 points or 17 while the sp 500 spx rose 11 and the nasdaq composite surged 17 tesla shares were up more than 9 while united airlines jumped more than 10 and american airlines rose more than 8