Financial Winners & Losers: AmEx

NEW YORK -- Shares of national banks mostly fell Tuesday on more signs of weakness in the financial sector.

American Express (AXP Quote) won approval late Monday from the Federal Reserve to become a commercial bank as it looks for new ways to fund its business. The status will allow the credit card giant to accept deposits and permanently access government financing that's been used by other banks amid the credit crisis.

AmEx shares were falling 2.8% to $23.30 in recent trading.

Citigroup (C Quote), meanwhile, became the latest big bank to announce sweeping efforts to try and curtail losses from souring mortgage loans. The New York-based bank said it is imposing a moratorium on most foreclosures as part of a series of initiatives aimed at helping at-risk borrowers stay in their homes.

Additionally, over the next six months, Citi plans to reach out to 500,000 homeowners who are not currently behind on their mortgage payments, but who are deemed as potentially needing assistance to keep current with their payments. This represents about one-third of all the mortgages that Citigroup owns, the bank said.

JPMorgan Chase (JPM Quote) and Bank of America (BAC Quote) have also become more aggressive in modifying loan agreements in the face of mounting defaults and plunging home values.

Citi shares were falling 1.4% to $11.05 in recent trading. Earlier in the session, shares fell as low as $10.65 -- their lowest point in 13 years.

JPMorgan was rising 1.5% to$36.95, while Bank of America was dipping 1.3% to $19.22.