SABIC, which is Clariant's largest shareholder, said the increase was part of its strategy to achieve a leadership position in the Specialties business.
The company's decision to hike its stake comes after it took an impairment charge of 1.5 billion riyals ($400 million) on its investment in Clariant in its third quarter.
SABIC is just shy of the one-third stake that would require it to make an offer for all of Clariant, but Clariant said it did not expect the Saudi chemical giant to seek a takeover.
SABIC had previously said it had no interest in taking Clariant over after the Muttenz-based company shelved a joint venture plan in July last year.