NEW YORK – Bank of America, Citigroup and PNC Financial Services Group may face added costs or fines after investigators questioned the use of a mortgage database instead of original documents to justify foreclosures.

Earnings at Bank of America, the largest U.S. lender, may suffer materially if using Mortgage Electronic Registration Systems is found to be invalid, according to a late February regulatory filing. Citigroup and PNC said fines or other penalties may result from investigations into MERS and allegations of faulty foreclosure practices.

“They’re recognizing the writing on the wall, that there are serious problems associated with the basic business model and legal theories of the MERS system,” said Christopher L. Peterson, a law professor at the University of Utah in Salt Lake City who has written articles on Reston, Va.-based MERS.

MERS is a private database run by closely held Merscorp Inc. that tracks ownership in about half of all home mortgages. It allows banks to buy and sell loans without having to record transfers with the county, and some lenders named MERS as their agent to bring foreclosures. Consumer advocates argue that MERS records aren’t a legal substitute for traditional documents, prompting some courts to throw out foreclosures.

Merscorp said on Feb. 16 it will propose a rule change to stop members from foreclosing in its name. It is owned by Fannie Mae and Freddie Mac, the government-owned mortgage companies that have received $151 billion in government aid since 2008, and financial firms including Bank of America, Citigroup and JPMorgan Chase, according to the MERS website.

Bank of America said legal challenges against MERS have asserted that use of the system can “cloud ownership” of a loan, according to its filing.

The Charlotte, N.C.-based lender, which ranks second in home lending and first among mortgage servicers, said it uses MERS for “a substantial portion” of new home loans, including those sold to investors or transferred into securitized trusts.

The process “is based on a well-established body of law that establishes ownership of mortgage loans by the securitization trusts, and we believe that we have substantially executed this process,” Bank of America said in its filing.

The question of MERS’s “legitimacy” drew scrutiny from the Justice Department and Congress as well as regulators and state attorneys general, Citigroup said in its filing. The bank “has determined that the integrity of its current foreclosure process is sound,” the New York firm said.

PNC, the sixth-largest U.S. bank, expects to sign consent orders with U.S. regulators for remedial actions tied to mortgage servicing and foreclosures, according to a filing with securities regulators.

The Pittsburgh lender cited its use of MERS among the matters covered by the orders, which it said are likely to come from the Federal Reserve and the Office of the Comptroller of the Currency.

“We believe that PNC has systems designed to ensure that no foreclosure proceeds unless the loan is genuinely in default,” the bank’s filing said.

Fred Solomon, a spokesman for PNC, declined to comment on MERS.

Regarding the consent orders, Solomon said, “we take this very seriously, and PNC is committed to doing the right thing for its customers.”