Noble Group's co-CEO Jeffrey Frase quit on Monday, a surprise move that comes just three days after embattled commodity trader reported a third-quarter loss of $1.17 billion.

The Hong Kong-based firm had named its president William Randall, and Jeff Frase, global head of oil liquids, as co-CEOs in 2016 after a surprise departure of then CEO Yusuf Alireza.

Randall will serve as Chief Executive Officer and continue as an Executive Director of the Noble Group, the company said in a statement released after market hours.

The company did not elaborate on the reason for Frase's departure, except that he was looking "to pursue other opportunities outside of the Group".

Frase was the guiding force behind the expansion and profitability of the Group's global oil liquids platform in recent years and the proposed disposal to Vitol Group last month.

"With the completion of the Proposed Disposal expected by the end of 2017, Mr. Frase has decided to resign as Co-CEO and Global Head of Oil Liquids to focus on other opportunities where his leadership, market knowledge and extensive network can be leveraged," Noble Group said in a statement.

Shares in Noble Group plunged 12 percent at S$0.22 on the Singapore Exchange on Monday.

The company reported a third-quarter loss of $1.17 billion last week and warned that the operating environment remains challenging.

Noble has been battered by a savage downturn in commodity markets and concerns about its accounting.

The company, which commenced its strategic review earlier this year, has been forced to shrink its business, exiting loss-making and non-core operations in order to survive.

Noble was accused in February 2015 by Iceberg Research of overstating its assets by billions of dollars, claims which Noble rejected.