Portugal's Espirito Santo International said it cannot pay off its debt and filed for creditor protection in a Luxembourg court on Friday.
The conglomerate partly holds Banco Espirito Santo, a major lending institution in Portugal whose shares were temporarily halted from trading recently due to concerns over the bank's financial health.
Espirito Santo International's main holding is Rioforte Investments, a real estate entity that failed to repay more than $1 billion euros in debt earlier in the week.
Once Espirito Santo International's request is approved, it will not face any more enforcement actions by creditors, according to a company statement.
Portugal's central bank has said that Banco Espirito Santo had enough capital to withstand the troubles of its holding company.
—By CNBC.com. Reuters contributed to this report.