The country's biggest dry bulk shipper said in a filing to the Korea Exchange that the investment stemmed from its long-term plan to secure ships.
In a separate filing, STX Pan Ocean said it posted a 63 percent jump in quarterly net profit to 169.9 billion won in the second quarter.
April-June sales more than doubled to 2.37 trillion won from the previous year.
Shares in STX Pan Ocean closed 2.45 percent higher at 1,885 won. ($1=1033.7 Won)