Cardinal Gregorio Conti is elected Antipope Victor IV. During the papal election of 1130, Gregorio Conti was one of the cardinals who voted with the majority for Pietro Pierleoni (who became Antipope Anacletus II) rather than the minority who elected Pope Innocent II. When Anacletus II dies, the cardinals supporting him elect Conti as his replacement.
In just a couple of months, Antipope Victor IV will repent and offer submission to Innocent II.
The pope initially restores Gregorio Conti to his original office, but in April 1139 the Second Lateran Council condemns and deposes all those involved with the election of antipopes over the past few years.