A plan by Assured, which writes insurance policies that trigger when a bond issuer fails to repay its bondholders, to sell $300 million worth of shares should further boost the company's capital position, Fitch said.

Fitch lists Hamilton, Bermuda-based Assured's issuer financial strength as "AAA", and said the company's rating outlook is "Stable." The issuer financial strength of Assured's mortgage insurance subsidiary is rated "AA".

Fitch last month said it would review its ratings on highly rated collateralized debt obligations -- the financial instruments backed by pools of assets such as mortgages that have dragged down financial companies' profits this year -- that are insured by financial guarantors. The rating firm said then that Assured's risk from risky CDOs is likely lower than that of its competitors.

Assured introduced its plan to sell the shares, subject to market and other conditions, on Wednesday. As part of the stock offering, Assured will grant its underwriters an option to buy $45 million worth of additional shares. Banc of America Securities LLC and Merrill Lynch & Co. will act as joint bookrunners.

Assured shares rose 7 cents to $21.52 in after-hours trading. The stock fell 73 cents to $21.45 during the regular session.