This study investigates the market response to the
requirement that the principal executive and financial
officer of an SEC registrant each state under oath that
the firm's annual and quarterly financial reports are
materially accurate and complete pursuant to the Securities
Exchange Act of 1934. We hypothesise that investors
should recognise the importance of these changes in
financial reporting and, thus, respond at or around
those events that should reveal the most information
about those changes, specifically, the SEC order to
certify (27 June 2002), the passage of the Sarbanes-Oxley
Act (25 July 2002), and the first certification filing
by a registrant. We find that investors did respond
on the identified dates, and in the ways hypothesised.
We conclude that investors responded to certification
and / or Sarbanes-Oxley.