Ambac Financial Group Files Bankruptcy to Restructure Bond Debt まあ、わかっていたとはいえ、アメリカでもっとも収益見通しが明るいと言われた会社だ・・・・ Nov. 9 (Bloomberg) -- Ambac Financial Group Inc., a holding company for the bond insurer being restructured by state regulators in Wisconsin, filed for bankruptcy with liabilities of $1.68 …