By purchasing 205.7 million shares at the price of VND113,000 ($4.85) each, SK has secured a 6.15 percent stake in the Vietnamese company.
Vingroup in March sought its shareholders’ vote on a plan to raise at least VND25 trillion ($1.08 billion) through a private placement to foreign investors.
It planned to use VND10 trillion ($432.3 million) of the proceeds to restructure its debts, VND6 trillion ($259.4 million) to invest in its auto company VinFast, technology firm VinTech and smartphone maker Vinsmart.
Vingroup is Vietnam’s largest listed company by market capitalization and is worth VND368 trillion ($15.8 billlion).
SK is among the largest conglomerates in South Korea with businesses in telecommunications, technology, electronics, logistics and service.
Last year, it had a revenue of $132 billion, with total asset worth $184 billion.
In September, SK Group acquired a 9.5 percent stake in Vietnam’s diversified business Masan Group for $470 million.