Two things have changed from six months ago. People are more confident about funding in Europe and people are pleasantly surprised about the robustness of the U.S. economy, especially around the labour market and consumer spending, Diamond told Reuters, after speaking to analysts and investors at a Morgan Stanley conference on Tuesday.
We're not overly optimistic, as there are still political and economic headwinds out there. But certainly the first quarter has been pleasing, he added.
Diamond's comments were echoed by HSBC
Investment banking in particular had been hit hard in the second half of 2012 at most major firms by turmoil in the euro zone, dragging down trading volumes in bonds and stocks.
Barclays warned in February it might not achieve its 13 percent return on equity profit target for next year after its investment bank ended 2011 with its worst quarter for three years.
The more than 1 trillion euros loaned to banks since December by the European Central Bank has helped ease funding fears in the region, while a long-awaited deal with private investors to bail out Greece was struck in March.
(Reporting by Steve Slater; Writing by Sarah White; Editing by Greg Mahlich)