Credit ratings agency Moody’s Investors Service has warned that it will be difficult for most wholesale investment banks to maintain or achieve stand-alone Aa ratings, and that their risk profiles remain “concentrated, interconnected, and opaque”.

Moody's analysts said in a report yesterday that the outlook on the ratings of most wholesale investment banks remains negative, and they are unconvinced that "reliable repairs" have been carried out, particularly among those banks that have taken big losses.