BofA responded to the complaints data by praising the goal of transparency at the Consumer Financial Protection Agency, the watchdog agency that was created in response to the 2008 financial crisis.
BofA also pointed out that 98 percent of the complaints reported by the agency were listed as resolved.
But the data show BofA was way out in front on complaints complied since December 2011 and that its purchase of Countrywide was the principle reason.
BofA bought Countrywide in 2008, just as the financial meltdown was unfolding and the California lender at the time was the country's largest mortgage firm. Its specialty: risky, subprime mortgages.
By the numbers, the CFPA said BofA had 15,136 complaints since December 2011, about 30 percent of all complaints the agency handled. Two-thirds of the BofA complaints involved mortgage modifications, the Los Angeles Times reported Friday.
The information "enforces what we already knew – that Countrywide was a hot mess," said banking industry analyst Nancy Bush.
"The lack of infrastructure at Countrywide left Bank of America in the lurch from day one when it came to enacting the tsunami of directives that came at them [from regulators] after the meltdown," Bush said.
BofA handles 15 percent of all U.S. residential mortgages.
Wells Fargo handles a larger share of the market, servicing 21.5 percent of the country's home loans but was responsible for less than 16 percent of complaints involving mortgages.
JPMorgan Chase customers generated 10 percent of the mortgage complaints, while that firm handles 12.7 percent of the market share.
Citibank and U.S. Bancorp round out the top five, serving 5.2 percent and 2.9 percent of the market, respectively. Those banks generated 4.8 percent and 1.7 percent, respectively, of all the mortgage-related complaints, the Times said.