Adaptive Biotechnologies is trading 5.71% lower at $27.75 in after-hours trading; no clear catalyst for the decline was identified. - Shares closed at $29.43 on September 25. - A September 25 announcement highlighted new international multiple-myeloma guidance placing highly sensitive MRD testing, including clonoSEQ, in the assessment of whether patients meet a definition of cure. The news does not clearly explain the decline. - Major U.S. indexes rose Friday, so broader-market weakness does not account for the drop.