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A customer uses a Bank of America ATM on September 29, 2011 in Los Angeles, California. Bank of America annouced its plans to start charging a $5 monthly fee for customers using their debit card for purchases starting early in 2012.\r\n

NEW YORK — On a normal day, 4 billion shares of stock change hands on the New York Stock Exchange. One in 10 belongs to a single company. It's not McDonald's or IBM, both of which have been on a tear.

It's Bank of America — bailed out by the government three years ago, reviled for being part of the mortgage frenzy that helped wreck the economy and selling for not much more than an ATM fee.

When the market goes up because of positive news about the economy, Bank of America stock shoots up past the stocks of other big banks. When traders get worried about Greek debt, Bank of America takes the biggest plunge.

The big swings are not driven by a fundamental bet that the bank will be more profitable because the economy is getting better or a real concern that it will lose more money than others if there is a default in Greece.

Instead, Bank of America is the stock of the moment for high-frequency trading, the supercomputer-driven buying and selling that barely existed a few years ago and now accounts for as much as two-thirds of U.S. trading.

The bank's single-digit stock price and flood of shares on the market — three times as many as its nearest big-bank competitor — make it an attractive target for hedge funds and banks that employ high-powered, computerized trading.

"The movement of Bank of America stock on most days has nothing to do with Bank of America," says Joseph Saluzzi, co-founder of brokerage firm Themis Trading.

In other words, the stock moves because it moves. Bank of America stock has risen or fallen 1 percent or more on 20 days this year. The Standard & Poor's 500 index has only done it three times.

For the year, Bank of America is up 46 percent, best of the 30 stocks that make up the Dow Jones industrial average.