Shares in American International Group plunged after the world’s largest insurance group by assets said it could offer “no assurance” that its huge credit market losses would come to an end any time soon.

After the market closed on Thursday, AIG reported a net loss of $7.8bn after it revealed $15bn in credit-related writedowns and said it would raise $12bn in fresh capital to bolster its balance sheet. The insurer also said it would move Steve Bensinger, chief financial officer, to another job and begin a search for a new CFO.