North America’s largest producer of vinyl building products Axiall, based at Atlanta, Georgia, USA, has rejected a $1.4 billion bid from rival US vinyls producer Westlake, headquartered at Houston, Texas.

The “unsolicited and conditional” cash-and-stock offer, as the Atlanta company described it, was dated Jan. 25 and publicly disclosed by Westlake on Jan. 29 after Axiall’s board of directors unanimously rejected it.

"Westlake’s proposal is an opportunistic attempt to take advantage of challenging public equity market conditions and significantly undervalues Axiall’s assets and its long-term prospects,” CEO Timothy Mann said in a statement.

The $33 per share bid is substantially higher than the company’s $20 per share closing price on Jan. 28.

In its previous incarnation as Georgia Gulf, before the 2013 merger with parts of US chemicals and paint producer PPG, the company was also the target of a Westlake takeover attempt.

At the beginning of January 2012, the Houston firm made a $30 per share offer, valuing Georgia Gulf at just over $1 billion.

Over the past year, Axiall has been under considerable pressure from institutional investors to cut a deal. Brigade Capital Management, which holds 2%, suggested opening talks with Westlake Chemical Corp to negotiate a better offer.

The biggest investor, Shapiro Capital Management, which holds 8.6%, wrote to the company’s management in June 2015, urging it to consider strategic options, including a sale. A month earlier shareholder Franklin Resources said Axiall should explore selling parts or all of its business.

Westlake, which in 2014 acquired German PVC producer Vinnolit from Advent International for €490 million ($666 million) is believed to be especially interested in gaining access to Axiall’s 50% stake in the shale gas-fed ethane cracker being built in a partnership with South Korea’s Lotte.

The takeover also would provide the Texas company with additional ethylene and chlorine assets to feed its vinyls business.

Westlake CEO Albert Chao said in a statement he was "surprised and disappointed" by Axiall’s rejection. Chao’s family is believed to own 70% percent of Westlake.