American International Group Inc, the world's largest insurer, posted its largest ever quarterly loss on Thursday and said it would raise $12.5 billion to fortify its balance sheet.

The result marked the second consecutive quarter that AIG had posted record losses, hurt by a write-down of derivatives exposed to bad mortgage investments.

Separately, the company said it was looking for a new CFO after naming Steven Bensinger vice-chairman of financial services, effective immediately.

AIG said the first-quarter net loss was $7.81 billion, or $3.09 a share, compared with net income of $4.13 billion, or $1.58 a share, a year earlier.

Included in the results was a $9.11 billion charge for unrealized market valuation losses on credit swaps, a portfolio that also proved a thorn in the fourth-quarter.

AIG also recorded capital losses of $6.09 billion, primarily from impairment charges in its investment portfolio.

AIG said it expected to raise $7.5 billion of the total capital through a common stock and equity-lined offering.

On an adjusted basis. AIG said its net loss was $3.56 billion, or $1.41 a share, AIG said.