SK Group's total market capitalization surpassed ₩2,000 trillion ($1.32 trillion) for the first time on June 16.
The group is now the second South Korean conglomerate to reach this valuation after Samsung Group.
A semiconductor sector rally drove the milestone through significant gains in key affiliates.
Chipmaker SK hynix Inc. accounts for approximately 84% of the group's total market value.
SK hynix shares rose 4.11% on the day to reach a record-high closing price.
Investment firm SK Square also reached a new all-time high stock price.