Banks have seen a $54bn hit from monoline exposures since 2007

US BANKS have written down $54bn (£33.5bn) in losses resulting from their exposure to monoline insurers over the past four years, according to new data released by the International Swaps and Derivatives Association (Isda) yesterday.

The trade body for the over-the-counter derivatives market said that losses were greater than a figure of $2.7bn given by the US Office of the Comptroller of the Currency earlier in the year, after further analysis took into account derivatives related to subprime mortgage risks booked outside the domestic US banking system.

The new data covers 12 banks and bank holding companies, with four of the banks investigated accounting for $43bn of the total losses.

“This and the earlier study on losses from counterparty defaults provide additional evidence that structured real estate risk taken in synthetic form resulted in a large majority of losses taken by banks on derivatives during the crisis,” said Conrad Voldstad, Isda’s chief executive.

“Losses on plain vanilla products occurred but were relatively modest as the earlier paper revealed,” he added.