Advanced Drainage Systems is trading 19.74% up at $151.04 in after-hours trading after an unexplained surge on September 18, 2026; the catalyst remains unconfirmed.
- No new company-specific earnings release, acquisition announcement, or regulatory filing is clearly linked to the move.
- The latest reported quarterly catalyst was August 6, when results beat estimates.
- The broader market was constructive, but its gains do not explain the magnitude of this move.