Coherent is trading 4.3% down at $287.11 amid a broader risk-off backdrop; no clear company-specific announcement explaining the decline surfaced in available reporting. - Reuters reported Brent crude rebounded more than 3% on September 28 after President Trump rejected Iran’s peace proposal. - Market coverage also cited rising Treasury yields as a drag on sentiment. These macro forces are plausible context, not confirmed direct causes of Coherent’s move.