The financial terms of the deal were not disclosed.
"The transaction accelerates delivery of ADNOC's global chemicals growth strategy and reinforces its status as a responsible, long-term partner and growth-oriented investor," ADNOC said in a statement.
The state energy firm said through the deal it has increased its shareholdings in both petrochemicals group Borealis and Abu Dhabi-listed Borouge, without disclosing the ownership ratios.
Last July, ADNOC entered into talks to merge petrochemicals group Borealis - owned by OMV and ADNOC - and Abu Dhabi-listed Borouge (BOROUGE.AD), opens new tab, owned by ADNOC and Borealis.
