In an event study, the abnormal return is described as theMultiple Choicetotal return eared by a security on the date of an announcement affecting that securitytotal retum earned on a security for the $7-$day period commencing three days prior to an announcement affecting that security.any change in the market price of a security that exceeds five percent over a $7-$day periodchange in market value of a security on the day of an announcement affecting that security.actual return on a security minus the market rate of return on the same date