Barclays reported a 5 percent fall in adjusted pre-tax profit to £1.7 billion ($2.9 billion) on Tuesday as the fixed-income division of its investment bank continued to slow.
The bank's interim management statement comes ahead of a large-scale reorganization, expected on Thursday, in which a major shake-up of its investment banking operations is expected.
Net profit at the bank rose to £965 million for the quarter.
Its investment bank suffered a 28 percent fall in income, after income at the fixed-income, currencies and commodities wing plummeted by 41 percent.
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The division is facing job cuts and restructuring in Thursday's announcement.
In a statement, Antony Jenkins, chief executive of Barclays, said: "This plan will address issues underlying the performance challenges we have recently experienced, including positioning the Investment Bank for the new operating and regulatory environment."