>> the oil services company halliburton have seen its shares drop 15% on revelations on its work on the exploded bp oil rig. an inquiry has found it should have known cement used to seal the well was unstable but carried on regardless. previously halliburton claimed the design of the rig was the problem. 11 workers were killed, of course, in america's biggest offshore oil spill in the gulf of mexico. the current argentinean president, christina fernandez kitsch ner, has led tributes to her husband. he was her predecessor as leader and widely expected to run for president again. hundreds gathered to pay their respects. from buenos aires, we report now on a nation in mourning. >> mourners began gathering outside the main palace in buenos aires almost as soon as the president's death was announced and they kept coming and coming. many sleeping their overnight to be sure they have not missed the chance to pay their last respects to the man who governed them from 2003 to 2007.