General Motors is trading 4.02% down at $80.40 after a Cox Automotive forecast showed quarterly U.S. market-share losses. - The September 24, 2026 forecast showed U.S. vehicle sales declining 6.2% year-to-date and quarterly share falling to 16.7% from 17.4% a year earlier. - Reuters reported limited fuel-efficient offerings and no hybrid models are hurting demand amid elevated gasoline prices. - Elevated Treasury yields and inflation concerns may also add pressure, though company-specific market-share news is the clearest catalyst.