United Therapeutics is trading 6.82% lower at $506.31 in pre-market, with no confirmed company-specific catalyst identified. - The October 13 announcement of CHEST 2026 presentations is upcoming clinical-data news, but available reporting does not connect it to the selloff. - Overnight coverage noted Liquidia litigation developments, but did not establish that they explain the move. - Major indices are modestly higher, so broad-market weakness does not appear to explain the drop.