Consumer advocacy group Public Citizen filed a petition with federal regulators Wednesday urging the government to break Bank of America Corp. into smaller companies, saying the Charlotte bank poses a "grave threat" to the financial system.

In the petition to U.S. Treasury Secretary Timothy Geithner and Federal Reserve Chairman Ben Bernanke, the group said the Dodd-Frank financial reform law passed in 2010 gives regulators the authority to do so.

"Bank of America is too large and complex to manage or regulate properly, and its financial condition is poor and could deteriorate rapidly at any moment, potentially causing the market to lose confidence in the bank," the two-dozen-page document said.

A bank spokesman declined to comment Wednesday.

While Bank of America is aggressively shrinking its balance sheet to boost capital, chief executive Brian Moynihan also has defended his bank's size. At an economic forum Wednesday in Davos, Switzerland, he said the bank's size is necessary to support customers in different economies, MarketWatch reported.

The bank, the nation's second-largest by assets, saw shares slide nearly 60 percent last year amid fears of its continued mortgage troubles and overall economic unease. The stock has been one of the market's top performers in the opening weeks of 2012, though, as the bank reported a fourth-quarter profit and significantly higher capital and liquidity levels.

Shares closed at $7.35 on Wednesday, up about 1 percent from the previous day's close and up 32 percent for the year.

Bank of America earned $1.6 billion for common shareholders in the fourth quarter of 2011, a turnaround from the same period the year before, when the bank lost $1.6 billion. It also turned a small profit for the year.

Public Citizen's petition does not advocate a particular course of action, but it says "publicly available information is sufficient to show that financial regulators must take dramatic, assertive action to foreclose the possibility of catastrophic damage from Bank of America and fulfill the purposes of the Dodd-Frank Act."

In a separate letter to Geithner and Bernanke, a group of academics asked the government to investigate large banks to determine whether they are well-capitalized and whether they can be managed. They ask the regulators to "safeguard financial stability well before an immediate crisis materializes."