Bank of America has been fined $1.2bn (£910m) for failing to detect potential money laundering and other illegal activity, the US Treasury Department said on Tuesday.
The banking giant failed to report over $5bn in suspicious activity to the government, $1bn of which posed national security and illicit finance risks, the Treasury said.
Those failures included not flagging transactions that possibly involved Chinese money laundering networks or trade-based laundering "with a substantial nexus to the southwest border", according to the Treasury.
"Our team is far along with and committed to completing the work required to address the issues raised by our regulators," Bank of America told the BBC.
The announcement came less 24 hours before Bank of America was due to announce its quarterly earnings on Wednesday morning.
"Our third-quarter results will include a non-tax-deductible charge of $1.2 billion impacting net income by approximately 17 cents per share," the bank said in an emailed statement.
"We have already dedicated substantial personnel and resources to our ongoing remediation efforts, and those costs are in the current expense base," it added.
In announcing the fine, the third-largest the department has ever imposed, Treasury Secretary Scott Bessent said: "When a bank of this size fails to meet its anti-money laundering and sanctions obligations, the consequences extend far beyond its own walls, exposing the entire US financial system to significant illicit finance risks."
The Treasury said the bank overly relied on inquiries from outside parties like law enforcement and other financial institutions instead of its own internal controls.
This meant that it "effectively outsourced to third parties a substantial portion of its proactive detection and reporting obligations," the department said.
As part of the settlement, Bank of America admitted that it "willfully violated" the Bank Secrecy Act by failing to maintain a compliant anti-money laundering programme, conduct required due diligence on foreign correspondent accounts and file suspicious activity reports, the Treasury said.
The $1.2bn fine included penalties imposed by the Office of the Comptroller of the Currency (OCC) and the Office of Foreign Assets Control (OFAC).
The OCC's $750m fine marked the biggest penalty it has ever levied.
OFAC said its settlement with the bank was tied to 475 apparent violations of sanctions programmes including those on Russia and Iran, narcotics, and global terrorism.
The settlement amount of $11.6m reflected the determination that Bank of America's apparent violations were "non-egregious", OFAC said.