The Hart-Scott-Rodino waiting period for the all-stock merger of Olin and Huntsman has expired, clearing US federal antitrust review without a challenge, PU Magazine International reported on 16 September 2026. The deal was announced on 16 June 2026 as a merger of equals creating a company to be named OlinHuntsman, and shareholders of both companies approved it at separate meetings on 25 August 2026. The combined group is credited with approximately USD 12.5 billion of 2025 sales and would be headquartered in The Woodlands, Texas. Completion is expected in the first half of 2027, subject to further regulatory approvals and customary closing conditions.
The two portfolios sit on opposite sides of the same chain. Huntsman brings polyurethane systems, performance products and advanced materials; Olin brings chlorine, caustic soda, vinyls, epoxy and chlorinated organics. Under the agreed terms, Huntsman shareholders will receive 0.5476 Olin shares for each Huntsman share, leaving Olin shareholders with approximately 54.5% of the combined company and Huntsman shareholders with the remaining 45.5%. It is an all-stock transaction with no cash component, and no headline transaction value was disclosed.
The synergy target comes in two parts. The companies point to more than USD 300 million in cost savings and integration benefits, largely within two years of completion, together with a further USD 100 million in raw-material integration benefits from 2031. That split is consistent with the "$400+ million of identified and actionable cost synergies and integration benefits" cited in the 16 June joint announcement. The 2031 date on the raw-material line is the part worth noting: it sits well beyond the two-year integration window, which implies physical or contractual reconfiguration rather than overhead removal.
Huntsman is both one of the handful of global MDI producers and one of the largest polyurethane system houses in the world, which makes this an unusual pairing: a formulated-systems business merging with a chlor-alkali producer. Chlorine is the feedstock for phosgene, and MDI is made via phosgenation, so deeper backward integration in the isocyanate chain is the obvious reading of the raw-material synergy line. That inference is ours: neither company spelled out the chemistry in the announcement.
For an independent system house, the merger matters less as news than as a structural question: whether integrated producers widen their cost advantage on the isocyanate that everyone else has to buy. Huntsman is simultaneously a competitor in formulated systems and, for many regional blenders, an upstream supplier, so consolidation at that level touches both sides of the relationship at once. Nothing changes before completion, which is expected in the first half of 2027 and still depends on further regulatory approvals. The reasonable response now is to track supplier concentration in MDI and in systems, not to re-plan sourcing around a deal that has not closed.