Swiss speciality chemicals maker Clariant said on Tuesday it had made a mandatory public offer for the 3.85% of Süd-Chemie shares it does not own. Clariant, which beat rivals to buy German group Süd-Chemie for €1.4 billion ($2 billion) in February, will offer €126.38 per share.

The offer will run from May 17 to June 14, Clariant said. Last month, Clariant launched a right's issue to help fund the acquisition - its biggest buy in a decade - that will give the company access to Süd-Chemie's booming catalyst business.  In February, Clariant said it was issuing new shares in a 1.1 billion Swiss franc ($1.2 billion) capital increase to help finance the deal. It will exchange 700 million francs worth of shares with Süd-Chemie family shareholders.

Süd-Chemie is mainly coveted for its catalysts unit which caters to the huge petrochemical industry in the Middle East, including Saudi Basic Industries Corp (SABIC), the world's biggest petrochemicals company by market value.