Brevan Howard, one of the world's largest hedge funds, lost almost $4 billion in assets in nine months, according to an analysis of client documents by Business Insider. The firm's flagship fund returned 2.65% this year through January 26, according to a person familiar with the numbers. Brevan Howard's assets have dropped by about $4 billion in nine months, according to an analysis of client documents by Business Insider. But it's had a solid start to 2018. As of the end of March 2017, the firm managed $13.3 billion. By year end, it had just $9.5 billion.