Bank of America Corp, the No. 2 U.S. bank by assets, posted a first-quarter profit, narrowly beating analysts' estimates, as legal costs fell steeply and the bank earned more from mortgage lending and investment and brokerage services.

BofA reported a surprise loss in the year-earlier quarter after taking a charge of $6 billion for legal costs.

The bank's litigation expenses fell to $370 million in the latest quarter, suggesting again that the worst of its legal troubles may be over.

Higher legal bills have been undermining cost-cutting initiatives introduced by Chief Executive Brian Moynihan since he took the bank's top job in 2010.

BofA has booked at least $70 billion in legal expenses to settle disputes stemming from before and during the financial crisis. An $8.5 billion settlement with mortgage securities investors - the bank's largest related to the financial crisis - got court approval in March.

Non-interest expenses fell 29.4 percent to $15.7 billion in the quarter ended March 31.

"At a time of continued low interest rates, we had good expense control...," Moynihan said in a statement.

BofA reported net income of $2.98 billion, or 27 cents per share, attributable to common shareholders compared with a loss of $514 million, or 5 cents per share, a year earlier.

The bank earned 30 cents per share, according to a Thomson Reuters calculation. This calculation included a charge of 6 cents per share for annual retirement eligible incentives, but excluded a charge of 3 cents per share from market-related net interest income adjustments.

Analysts on average had expected earnings of 29 cents per share, according to Thomson Reuters I/B/E/S.

BofA's shares were down 0.8 percent at $15.69 in premarket trading on Wednesday.

Revenue from fixed income, currencies commodities trading fell 6.8 percent to $2.75 billion.

However, revenue from foreign exchange sales and trading doubled, helped by the Swiss central bank's shock move in January to remove the franc's three-year-old cap against the euro that set off a frenzy of trading.

Mortgage banking revenue rose 68.4 percent to $694 million, while income from investment and brokerage services rose 3.3 percent to $3.38 billion.

Overall revenue, excluding certain adjustments, fell 5.9 percent to $21.42 billion. That contrasted with the revenue gains reported by J.P. Morgan Chase & Co and Wells Fargo & Co on Tuesday.