The company received a message regarding "certain potential accounting matters" in mid-February and postponed filing its quarterly and annual reports because of the investigation.
ComScore executives said in May that the company would provide an "informed update" by Mon., June 27. Shares of ComScore tumbled more than 20 percent Tuesday after the internet analytics company missed its self-imposed deadline.
"The Audit Committee continues to work vigorously to complete its review and to report its findings to the board," the company said, in the SEC filing.
The committee has completed a substantial amount of factual inquiries but require further time to evaluate the information collected and reach a conclusion, the company added.
The company did not offer a deadline this time.
ComScore's stock has plunged this year, falling more than 43 percent.
ComScore 2016 Chart