It is unclear which investment bank was responsible for the error, but West LB, Morgan Stanley and JP Morgan all denied they were responsible.
As a result of incorrect market participant order entries, Eurex cancelled certain trades in futures and options on the DAX and Euro Stoxx 50 indexes. The cancellation affected trades between 9:21am and 9:25am. All DAX futures trades that traded below 5,083.5 points for December expiry and below 5,121 points for March 2002 expiry were cancelled. In the Dow Jones Euro Stoxx 50 futures trades were annulled that traded below 3,726 points for December and under 3,750 points for March, and less than 3,733 for the June 2002 expiry. Trades in options on the DAX and the Dow Jones Euro Stoxx were cancelled according to the respective mistrade rules.
DAX futures stood at 5,165 points before the trade was executed, but fell to 4,348 before recovering shortly after the rogue trade was executed.