XM Satellite Radio Holdings and Sirius Satellite Radio said on Thursday they received a request from the U.S. Department of Justice for additional information regarding their proposed merger.
U.S. antitrust authorities issue such a request if an initial review turns up potential antitrust problems. It requires the companies to turn up large amounts of information and is followed by a more in-depth investigation.
A spokeswoman for the Justice Department was not immediately available for comment. However, the department typically does not comment on merger investigations.