X0609 4 2026-10-02 0001598428 Metallus Inc. MTUS 0001554176 Williams Michael S false 1835 DUEBER AVE. SW CANTON OH 44706 true true false false Chief Executive Officer true Common Shares 2026-10-02 4 S false 12570 20.0066 D 722288 D Price reported is the weighted average sale price for shares sold by the reporting owner on October 2, 2026. Shares were sold at a variety of prices ranging from $20.0000 to $20.0100. The reporting person adopted a written plan for the sale of the Company's common shares intended to satisfy the affirmative defense conditions of Exchange Act Rule 10b5-1(c) on May 18, 2026. All transactions reported herein were made pursuant to that plan. /s/ Kristine C. Syrvalin, as Attorney-in-Fact 2026-10-02