Siam Cement and PTT Global agree $5.5 billion petrochemical combination

Siam Cement and PTT Global Chemical have agreed to combine their Thai olefins and polyolefins businesses, valued at 187 billion baht ($5.5 billion), with PTT Global Chemical holding 56 percent of the venture and SCG Chemicals 44 percent, both boards having approved the deal ahead of shareholder votes on December 3.

Why it matters: The combination merges most of Thailand's olefins and polyolefins capacity into one venture under PTT Global Chemical's control, the largest restructuring yet of the country's petrochemical industry as regional overcapacity and weak margins force producers to consolidate.

Data as of Update 2026-10-28T22:24:11-04:00: the 56 percent and 44 percent holdings, the board approvals and the December 3 shareholder votes are from the accessible opening of Bloomberg News' report of October 29, 2026 (byline October 28, 9:10 p.m. EDT), read in full via the live browser in this run; Bloomberg attributes those terms to the companies' exchange filings of late Wednesday, but the filings themselves have not been read directly by this site and the remainder of the Bloomberg article sits behind its paywall, hence grade C. Earlier: the agreement and the 187 billion baht valuation are Bloomberg's reporting, relayed in identical terms by two aggregators, and no company filing announcing the agreement itself was in the feed queue when the item was first written. The scope of the businesses and the approval steps are from PTT Global Chemical's progress filing to the Stock Exchange of Thailand dated September 30, 2026. Developing item.

Latest, October 28: The terms are now set. PTT Global Chemical will own the remainder of the combined venture after SCG Chemicals, Siam Cement’s subsidiary, takes 44 percent, which puts PTT Global Chemical’s holding at 56 percent, Bloomberg reported, attributing the terms to the companies’ exchange filings late on Wednesday. Both companies’ boards have approved the deal, and shareholders of the two groups will consider it on December 3, 2026.

Siam Cement and PTT Global Chemical have agreed to combine their Thai olefins and polyolefins businesses in a venture valued at 187 billion baht ($5.5 billion), Bloomberg reported, as both groups seek to bolster petrochemical operations through a prolonged downturn. The agreement follows a study the two companies began under a memorandum of understanding in April 2026 and moves the combination from due diligence, where it stood at the end of September, to an agreed transaction. The $5.5 billion figure is the valuation of the businesses being combined, not a cash purchase price.

The scope set out in the companies’ September filing to the Stock Exchange of Thailand covers PTT Global Chemical’s Thai olefins and polyolefins assets, including its stake in HMC Polymers, and SCG Chemicals’ Thai crackers and polyethylene and polypropylene plants, together with its stakes in four joint venture companies. That filing had said PTT Global Chemical was expected to become the major shareholder of the venture, with SCG Chemicals remaining a significant shareholder, which the agreed 56 to 44 split now confirms, and that the transaction would need a filing to the Trade Competition Commission of Thailand plus internal corporate approvals.

Siam Cement and PTT Global agree $5.5 billion petrochemical combination

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