American International Group Inc’s decision to remove Peter Hancock as its chief executive was to avoid a proxy battle with billionaire activist investor Carl Icahn, the Wall Street Journal reported, citing people familiar with the matter.

AIG said last week that Hancock would step down, a decision he made after the insurer’s poor financial performance frustrated shareholders and its board of directors.

Hancock agreed to resign after several directors met with him to express concerns about his ability to continue improving AIG’s results, while several also feared a potential fight with Icahn, the Journal reported.

Icahn, AIG’s fourth-largest investor, cheered Hancock’s departure when it was announced: “We fully support the actions taken today by the board of AIG,” he had tweeted.

A decision “to stand by (Hancock) would carry the threat if not the reality of a battle with Carl,” a person familiar with the matter told the Journal.

When Icahn first began acquiring his stake in 2015, he advocated splitting up AIG into three parts. The insurer instead embarked on a two-year turnaround plan developed by Hancock, which the board is still committed to.

Many longtime AIG executives who would have been obvious internal candidates for CEO have left since Hancock took the helm in 2014.

Analysts have floated names of several external possibilities since AIG stunned Wall Street with a surprisingly wide fourth-quarter loss on Feb. 14.

Hancock, 58, will remain as CEO until a successor is named.