The last of the complex debt funds at the heart of the credit crisis is paying down senior creditors and withholding management fees in what could be the final chapter of the once $400bn industry.

Sigma Finance, a $28bn structured investment vehicle (SIV), was the largest and oldest of such funds, but due to continued problems with falling asset values and a lack of new funding, it has suffered a series of ratings downgrades that has exacerbated its difficulties.