U.S. Treasury yields were mixed on Monday as investors reacted to the announcement of the criminal investigation into Federal Reserve Chair Jerome Powell.

Powell said the investigation rests on “pretexts,” arguing it's retaliation for the Fed’s refusal to follow the Trump's preferences on interest rates.

U.S. Treasury yields were mixed on Monday as investors reacted to the announcement of the criminal investigation into Federal Reserve Chair Jerome Powell.

Former Fed Chair and Treasury Secretary Janet Yellen said she was "surprised the market isn't more concerned."

Justice Department probes Fed Chair Jerome Powell as tensions with President Trump over interest rates continue.