Credit Suisse First Boston and JP Morgan are underwriting a $420m (€347m) share issue for Converium. The two banks did not lead the initial public offering for the troubled Swiss reinsurer's three years ago. Since then the shares have plunged almost 70%.

Converium was spun off by Zurich Financial Services, the Swiss insurer, in 2001 with UBS as global coordinator and joint bookrunner with Merrill Lynch.