Old Lane, the hedge fund manager bought this year by Citi, and Fortress Investment Group, which listed this year, have joined the ranks of hedge funds reporting setbacks in August, including industry luminaries such as GLG Partners, Bluecrest Capital Management and Goldman Sachs' North America fund.

The $4.4bn (€3.2bn) Old Lane fund fell 5.9% last month, hurt by losses on debt and emerging market securities, according to Bloomberg, citing a report sent to clients. Its return for the year to date is still positive but has fallen to 1.9%. The firm was unavailable for comment.