Clariant AG (CLZNY) shares surged to a record high Monday after the Swiss chemicals group said it had agreed to an all-share "merge of equals" with U.S.-based Huntsman Corp. (HUN - Get Report)  that will be worth around $20 billion.

HuntsmanClariant will have sales of around $13.2 billion, the companies said in a statement, based on pro-forma 2016 sales and adjusted operating profit of $2.3 billion. The deal is expected to close before the end of the year, the companies said in a statement.

"This is the perfect deal at the right time," said Clariant CEO Hariolf Kottmann. "This is in the best interest of all our stakeholders. Peter Huntsman and I share the same strategic vision and I look forward to working with him."

Clariant shares leaped more than 9.3% in Switzerland Monday to change hands at €22.78 each, an all-time high, giving it a market cap of around €7.5 billion ($8.37 billion).

"Together we will create a global leader in specialty chemicals with a combined balance sheet providing substantial financial strength and flexibility," said Huntsman CEO Peter Huntsman.

Clariant shareholders will swap their existing stake for a single HuntsmanClariant share and will ultimate own 52% of the combined entity. Huntsman shareholders will receive 1.2196 in HuntsmanClariant stocks.

The combined group will be headquartered in Pratteln, Switzerland and will have a global operational hub in The Woodlands, Texas, a suburb of Houston and will have a dual listing on the SIX Swiss Exchange and the NYSE.

Huntsmann shares closed at $26.71 each in New York and a market capitalization of $6.6 billion,