WASHINGTON--The Justice Department is investigating high-speed trading practices to determine whether they violate insider-trading laws, Attorney General Eric Holder told lawmakers Friday.
Mr. Holder said the practice has "rightly received scrutiny from regulators."
"The department is committed to ensuring the integrity of our financial markets," Mr. Holder said in testimony about the Justice Department's budget before the House Appropriations Committee. "We are determined to follow this investigation wherever the facts and the law may lead."
The Federal Bureau of Investigation said earlier this week that it is probing high-frequency trading. New York Attorney General Eric Schneiderman, the Commodity Futures Trading Commission and the Securities and Exchange Commission are also looking into the practice.
Pressed by Rep. Jose Serrano (D., N.Y.), Mr. Holder acknowledged authorities aren't yet sure whether some types of high-frequency trading might violate federal law.
"I am really getting up to speed on this," Mr. Holder said, to which Mr. Serrano replied, "we all are."
The attorney general said the concern of federal prosecutors "is that people are getting an inappropriate advantage, an information advantage.. Milliseconds can matter, so we're looking at this to try to determine if any federal criminal laws have been broken."