Banks will have to provide details of their profits and losses from financial instruments under two measurement systems, according to proposed accounting changes that could come into effect for year-end accounts.

The proposals, from both the International Accounting Standards Board and its US counterpart, would require companies to disclose the profits and losses that would have been reported if financial assets were valued at current market prices and as if they were reported at “amortised cost” – a measurement that ignores market volatility.