ZURICH/FRANKFURT (Reuters) - U.S.-based Huntsman Corp HUN.N and Switzerland's Clariant AG CLN.S are combining to create a chemical manufacturer with a market value of about $14 billion, the deal coming together after years of tentative mutual approaches.

The HuntsmanClariant specialty chemicals company will be 52 percent owned by Clariant shareholders and valued at around $20 billion when including debt, Clariant said in a statement.

Many European companies have turned to dealmaking as growth in the chemicals industry has slowed. European businesses have particularly suffered, losing market share to rivals in Asia, where demand is growing more quickly, or to North America, where energy is cheaper.

Huntsman, controlled by the eponymous Mormon family, is best known for inventing the clam-shell styrofoam box for McDonald’s Big Mac burgers.

Based in the Texan town of Woodlands, Huntsman chemicals are also used in paint, clothing and construction. Clariant makes aircraft de-icing fluids, pesticide ingredients and plastic coloring.

The ownership split broadly reflects the relative weighting of each side’s equity market value, though the U.S. group is larger in terms of revenue.

The companies are stressing their equal footing in the deal.

Peter Huntsman, the son of the company founder, will become chief executive of the combined group while Clariant CEO Hariolf Kottmann will be its chairman.

The combined company will be headquartered in Switzerland, although its operational center will be in Woodlands.

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Clariant shares jumped as much as 9.7 percent to a 15-year high of 22.89 Swiss francs, but retreated to stand up 3.5 percent at 1525 GMT, while Huntsman stock was little changed after initial gains of up to 5.6 percent.

Though Clariant’s CEO said the deal had the backing of a group of Bavarian families that own almost 14 percent between them in the Swiss group, some analysts said Clariant might attract a higher bid.

“We think a counterbid might give higher upside for Clariant shareholders than the planned merger,” said Baader Bank Analyst Markus Mayer, without elaborating.

GETTING THE DEAL DONE

Reuters reported in March that Clariant and Huntsman had previously ended tentative merger talks late last year over a disagreement about who would play the lead role.

Kottmann and his counterpart Huntsman said they had developed a professional and personal friendship as long as eight years ago. Intensified talks over the past five weeks had resulted in a combination of the two companies.

“Hariolf and I had discussions as friends and as business colleagues. But this is the first time in all those years that we actually engaged our teams to actually get a deal done,” Huntsman told journalists on a conference call.

Kottmann has spent several years restructuring Clariant. He divested underperforming businesses including textile and paper chemicals in 2012 and placed more responsibility with lower level managers for faster decision-making.

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In mid-2015 he started carving out Clariant’s plastics and coatings business into a separately managed entity.

Plastics and coatings will be an integral part of the new company, Kottmann said, though he reiterated that it could be sold to fund any further takeovers.

Huntsman, for its part, will continue to pursue the planned initial public share offering of its pigments and additives business known as Venator.

UNDER PRESSURE

Investor pressure had been growing on management to identify a growth strategy for Clariant, which was formed in the mid 1990s from parts of Switzerland’s Sandoz and Germany’s Hoechst.

A source familiar with the transaction said the combined group would use its bigger fire power to pursue further deals.

Like Clariant and Huntsman, several rivals have taken steps to separate businesses and some are facing questions about their strategy as the remaining core business is seen as lacking critical mass, putting them potentially in play in M&A terms.

Among them, W.R. Grace, which competes with Clariant in process catalysts that speed up throughput of petrochemical reactors, split itself into two listed companies last year, spinning off GCP Applied Technologies GCP.N.

Ashland ASH.N, whose products include resins for tank and pipe linings and thickeners for sauces and ice cream, listed its Valvoline VVV.N engine oil unit on the stock exchange last year.

European peers BASF BASFn.DE, Solvay SOLB.BR, Evonik EVKn.DE and Lanxess LXSG.DE have agreed multi-billion takeovers since mid-2015.

A $130 billion merger and three-way split between U.S. groups Dow DOW.N and DuPont DD.N is underway, while Dutch paint and coatings group Akzo Nobel AKZO.AS is fighting an unwanted approach by U.S. rival PPG PPG.N.

Citi and UBS advised Clariant on the transaction, while Bank of America Merrill Lynch and Moelis acted as Huntsman’s financial advisers.