SK Inc, the holding company of South Korea's second-largest conglomerate SK Group, said it made the investment with affiliate SK Innovation as part of a total $750 million fundraising round co-led by Gates.

The investment in small modular reactors, which SK said is a competitive carbon-free energy source, goes toward SK Group's pledge in 2021 to reduce 200 million tons of carbon emissions by 2030, SK said in a statement.

(Reporting by Joyce Lee; editing by Jason Neely)