Blackstoneâ??s GSO Capital Partners and GoldenTree Asset Management, two prominent debt hedge funds, are turning to investors for more capital in the face of markdowns on their holdings and margin calls from their lenders.

In recent months GSO bought loans with a face value of $12bn that originated from private equity deals. GSO paid around 80 cents on the dollar for the loans, but has since marked down its holdings, resulting in margin calls from its banks. Instead of handing over collateral or selling parts of their holdings, GSO instead raised $100m from investors to meet the margin calls. In return investors will get stakes in a new fund that will hold many of GSOâ??s leveraged loans at larger discounts.

GoldenTree, which manages $11.5bn, created a "rescue share class" to raise $250m of new capital this month, it told investors. GoldenTree funds that relied on extensive leverage have been down almost 50 per cent in the year through October, according to investors. GoldenTree suffered particularly large losses in Europe, where it bought debt in smaller leveraged buy-outs and in private placements.

Leon Wagner, the chairman of GoldTreeâ??s, said it has raised about $500m in the past 60 days which "demonstrates the confidence of our clients."