Hedge funds are attacking bank decisions that help delinquent US mortgage borrowers remain in their homes in a move that pits some of the country’s richest people against its least well-off.

The dispute centres on derivatives contracts that pay money to investors when bonds backed by subprime mortgage loans – extended to people with past credit problems – run into trouble. The $1,200bn (€890bn) US subprime mortgage bond market has been hit recently by rapidly growing defaults, and hedge funds have profited from the crisis by buying such derivatives.