Global banks including Citigroup and UBS faced pressure yesterday to write down or sell billions of dollars in toxic assets following Merrill Lynch's disposal of $30bn (£15bn) in mortgage-related securities at a cut price.

Shares in Merrill and other financial companies rose on investors' hopes that the sale of collateralised debt obligations for $6.7bn, or 22 cents on the dollar, heralded similar deals by other banks to purge their balance sheets of bad assets.