Converium, the embattled Swiss reinsurer, has sold almost all the shares in its Sfr533 (€345m) rights issue to existing shareholders. The move paves the way for a credit rating upgrade that was contingent on a successful sale of the shares.

Nearly 100% of existing shareholders exercised their rights to buy additional stock leaving a small number of shares to be placed in the public market. The deal is due to close officially on Thursday.