Michael died June 25, 2009, at the age of 50 from an overdose of sedatives and anesthesia administered by his private physician Conrad Murray to help the insomniac artist sleep. Murray was subsequently sentenced to four years in prison for involuntary manslaughter.
Katherine sued AEG for more than $40 billion, claiming the company behind Michael's ill-fated concert tour was negligent in hiring Murray to care for Michael.
However, a jury in the civil suit against AEG decided last month the company was not responsible for Michael's death.
TMZ said Katherine is pursuing an appeal even though civil lawsuit verdicts are seldom overturned.