Amrize is trading 8.63% up at $42.85 after-hours, but the catalyst for the sharp gain remains unclear. - Amrize closed the October 23 regular session at $39.45; the supplied price context shows that session was essentially flat. - Search results did not identify a clear company-specific announcement on October 23. - Amrize’s third-quarter results are scheduled for October 28, while mixed market conditions do not clearly explain the gain.