Deutsche Bank, Germany's biggest lender, said Tuesday its net profit in the second quarter fell by 29 percent, due mainly to a heavier tax bill.
Ratings agency Moody's downgraded by a notch the bank's supported long-term debt and deposit ratings, citing "modest profitability" and "elevated earnings volatility" among the reasons.
The Frankfurt-based banking giant said its net profits came to 237 million euros ($318 million), compared to 334 million euros in the same period last year.
The profit figure was considerably lower than the 545 million euros analysts surveyed by Dow Jones Newswires had expected.
The company blamed a high tax bill for the decline in profits, notably higher non-deductible charges such as litigation expenses.
The bank's pre-tax profit actually rose by 16 percent year-on-year to 917 million euros as the group cuts costs.
But the group's total turnover fell by four percent to 7.9 billion euros in what the bank admitted was a "tough operating environment".
Co-chief executives Juergen Fitschen and Anshu Jain said the environment in which the bank was operating was "complex".
"The world's economies are growing at different speeds, and this may cause differences in the pace at which interest rates normalise, creating opportunities," the pair said in a statement.
Still, "emerging geopolitical events in Ukraine and the Middle East may impact financial markets and our clients, and we continue to adapt to a fast changing regulatory framework," the duo wrote.
Moody's, announcing its downgrade to A3 from A2, cited the impact of "litigation and restructuring costs and legacy losses, as well as elevated earnings volatility and high dependence on capital markets earnings" on Deutsche Bank's business.
The agency said in a statement that the bank is facing "adverse cyclical and structural industry trends" and regulatory challenges within its capital markets businesses.
"We are expecting modest earnings and a heavy reliance on capital markets revenues at Deutsche Bank for the foreseeable future and this drove the downgrade, despite the recent capital raise," said Peter Nerby, Moody's lead analyst for Deutsche Bank.
Due to "revenue and expense headwinds," Moody's said it expects Deutsche Bank's results to remain depressed until late 2015.