MBIA, the world’s largest bond insurer, on Thursday raised $1bn in equity in an effort to stave off cuts to its triple A credit ratings.

The plans, underwritten by JPMorgan and Lehman Brothers and with a backstop from private equity group Warburg Pincus, were announced on Wednesday as MBIA said it had increased its after-tax operating loss for the quarter ending in December by $65m to $472.8m.