Exhibit 99.1 Metallus Announces First-Quarter 2026 Results CANTON, Ohio: May 4, 2026 – Metallus (NYSE: MTUS), a leader in high-quality specialty metals, manufactured components and supply chain solutions, today reported first-quarter 2026 net sales of $308.3 million and net income of $5.4 million, or $0.13 per diluted share. On an adjusted basis (2) , the first-quarter 2026 net income was $7.7 million, or $0.18 per diluted share, and adjusted EBITDA was $24.6 million. This compares with the sequential fourt ...