A pair of the largest U.S. banks are expected to report big losses this week, including write-downs worth tens of billions of dollars due in part to the ongoing global credit crisis, triggered by bad bets in mortgage-related investments.

Among the major banks reporting this week, Citigroup and Merrill Lynch have been looking for billions more in additional capital from foreign investors. Citigroup may report a $4 billion loss on Tuesday, and Merrill Lynch, which reports Thursday, could have lost $3.2 billion loss, according to Bloomberg. JP Morgan, which reports Wednesday is expected to fare better. Since the start of the credit crunch this past summer, its earnings have not taken significant damage.

WRITE DOWNS

Citigroup may write off as much as $24 billion and lay off 20,000 workers, CNBC said Sunday on its website. The results could be revealed as soon as Tuesday. Merrill Lynch may write down as much as $15 billion, according to the New York Times.

SEEKING FOREIGN CAPITAL

To shore up its balance sheet, Citigroup is expected to raise as much as $14 billion from investors in China, Kuwait and others, Financial Times reported. However its plan to raise as much as $2 billion from China Development Bank could be in trouble due to opposition from the Chinese government, the Wall Street Journal said on Saturday.

Merrill is also in the hunt for $4 billion in capital, with the Kuwait investment Authority being a potentially large contributor to that amount, according to FT, which cited people familiar with the matter.

Citigroup received a $7.5 billion investment from Abu Dhabi in November. Merrill Lynch received the same amount in December in the form of a $6.2 billion investment from Singapore-controlled investment company Temasek Holdings and the rest coming from Davis Selected Advisers.

Merrill Lynch Investment Citigroup