FactSet Research Systems is trading at $273.09, down 4.9%, after-hours, with no clear company-specific catalyst identified. - It closed at $287.04 on October 9, 2026. Its investor-relations news list shows an October 8 partnership announcement, which does not explain the decline. - The broader market was positive on October 9, and available evidence does not point to a broad-market cause. - The move follows a 5.04% gain on October 8; the reason for the after-hours decline remains unclear.