Barclays said today that it earned GBP3.3 billion ($4.4 billion) before tax in the second quarter, up from GBP2.5 billion a year before.

In a volatile period for markets, one boost came from its trading division, where revenue rose 17% on year in dollar terms. Bond-trading revenue was almost flat but income from equity markets, a focus for the bank as it tries to move beyond its roots as a debt specialist, rose 44%.

But it couldn't keep up with its American rivals where, revenue from bond and commodities markets jumped 14% and equities revenue leaped 71%, according to Citigroup analysts.

Partly, that's by design. Under CEO C.S. Venkatakrishnan, Barclays has tried to limit the size of its investment bank and, within it, to prioritize more stable revenue sources like lending to hedge funds.

Plans to spend up to GBP300 million in the second half of the year on simplifying the bank's tech platforms and processes appeared to weigh on the stock. Shares fell more than 5% in London. CFO Anna Cross said the spending would reduce costs in the long run.