Bank of America will have to reduce expenses further in its markets trading division unless revenue improves, Chief Executive Brian Moynihan said.

"If the environment stays sort of flattish, less volatility, we'll have to keep working that expense base down," Moynihan said Wednesday at a conference in New York. "We've got to probably work it down again in the next couple of years if the business stays where it is."

B of A's global markets division posted a 28% drop in first-quarter profit to $945 million on declines in fixed-income trading revenue.

Revenue in the fixed-income, currency and commodities sales and trading division decreased 7% to $2.75 billion on declines in credit and mortgages. That trailed JPMorgan Chase's 5% increase.

At the same conference on Wednesday, JPMorgan CEO Jamie Dimon said his bank's trading revenue is on pace with last year's second quarter, when it was about $4.5 billion, not counting businesses that have since been sold. The bank generated $5.67 billion in 2015's first three months, which is typically the strongest quarter of the year.

"It could easily be worse than that, or higher than that as volumes change," Dimon said of the comparison to the year-earlier quarter. "We still have a month to go. And obviously the mix changes."

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