U.S. investigative authorities are looking into JPMorgan Chase’s two-billion-dollar trade blunder.

Federal Bureau of Investigation (FBI) Director Robert Mueller said in a meeting of the Senate Judiciary Committee on Wednesday that his agency began a preliminary investigation into JPMorgan Chase’s trade loss.

However, Mueller refused to elaborate on the detailed directions of the FBI investigation.

JPMorgan Chase’s trade mistake is also reigniting political discussions on the reform of Wall Street like additional regulations on the financial sector.