FRANKFURT — Deutsche Bank, Germany’s largest bank, said on Sunday that its net profit fell by half in the first quarter as it absorbed the legal costs of past wrongdoing by bank employees.

Profit in the first three months of the year was 559 million euros (about $608 million), Deutsche Bank said, down from 1.1 billion euros a year earlier. Although revenue rose 24 percent, to 10.4 billion euros, in the quarter, profit fell because of the 1.5 billion euros that the bank set aside to cover a legal settlement with United States and British regulators and law enforcement authorities.

On Thursday, Deutsche Bank agreed to pay penalties totaling $2.5 billion to settle charges it had colluded with other banks to manipulate benchmark interest rates, including the London interbank offered rate, or Libor. The rate is used to set the rates on credit cards, mortgages, student loans and trillions of dollars in other debt.

The impact of the penalty overshadowed a rebound in Deutsche Bank’s investment banking unit. The bank said that revenue generated from trading stocks, bonds and currencies was the best it has been in years. Revenue from investment banking rose 15 percent, to 4.7 billion euros, but profit plunged more than half to 643 million euros after subtracting the penalty.