about bank capital cushions and a darkening economic outlook in Europe.

When Mr. Moynihan was appointed to the top job on Dec. 16, 2009, Bank of America was trading near $15 a share, a far cry from the $4.99 at which it closed Monday. The loss of two-thirds of its value far exceeds the drop in other battered financial institutions like Citigroup, JPMorgan Chase and Wells Fargo over the same period.

“This is like a fire in a 10-story building,” said Mark T. Williams, a former Federal Reserve bank examiner who now teaches courses on banking at Boston University. “It’s burning through each floor as investors dump their shares.”

Financial stocks fell by more than 2 percent Monday in the United States, leading the entire stock market down. The Dow Jones industrial average closed off 100.13 points, or 0.8 percent, at 11,766.26. The Standard & Poor’s 500-stock index was down 1.2 percent, and the Nasdaq composite index fell 1.3 percent. The Dow is now down more than 2 percent this month, while the S.& P. is down more than 3 percent.

Trading on Wall Street had opened higher, but then turned negative in the late morning. Analysts said that market moves were expected to be exaggerated, with lighter volumes in a holiday week.

During the day, some focus shifted to European sovereign debt troubles as the European Central Bank warned of a perilous year ahead. The sovereign debt crisis is colliding with slower economic growth and a dearth of market financing for banks.

A report in The Wall Street Journal that the Federal Reserve would rebuff pressure from American banks and go along with international recommendations on capital levels for banks also affected the markets, analysts said.

Citigroup fell 4.7 percent and Morgan Stanley 5.5 percent.

For Bank of America, which tumbled 4.1 percent, trading below $5 represents one more embarrassment this year. The company, based in Charlotte, N.C., recently lost its title as the country’s largest bank by assets to JPMorgan Chase. More than anything else, Bank of America’s problems stem from its disastrous 2008 acquisition of Countrywide Financial, the subprime mortgage giant whose excesses have come to symbolize the housing bubble of the last decade. It now faces lawsuits from investors seeking to force it to buy back billions in soured mortgages.

In addition, slow economic growth and ultra-low interest rates are eating into profit margins in traditional businesses like commercial lending. What’s more, capital markets where banks help companies raise money and make deals have slowed in recent weeks, hurting results at Bank of America’s investment banking unit.

Even a $5 billion investment by Warren E. Buffett this summer has failed to mollify sellers — he has lost roughly $1.5 billion on paper, although the generous terms of his purchase agreement protect him against losses.

Along with more fundamental factors, institutional money managers are also quietly dumping their losers before 2012 arrives, a practice known as “window dressing,” which removes stocks like Bank of America when investors read year-end reports.

“It’s a headache that a lot of money managers don’t want,” said one mutual fund manager who insisted on anonymity because he wasn’t authorized to speak publicly. “Managers don’t want endowments and other clients asking them why they own Bank of America.”

 Some observers have speculated that going below $5 would force some institutional investors to unload Bank of America stock because of rules forbidding them to own shares in the low single digits. But Glenn Schorr, an analyst with Nomura, played down the likelihood of that.