Summit Therapeutics is trading 4.23% down at $16.41 on October 13, 2026, with no clear company-specific announcement explaining the decline in available search results. - Recent AstraZeneca and Daiichi Sankyo collaborations are earlier news, not evidence of a cause for this move. - The November 14 FDA decision date for ivonescimab is an upcoming catalyst, but there is no evidence it specifically triggered today’s drop. Major indices are mixed, with no broad same-direction move explaining it.