Updated from Jan. 11

Saudi billionaire Prince Alwaleed may make a significant investment to help out cash-strapped Citigroup ( C), according to media reports.

On Friday, CNBC reported that the Saudi prince might invest as much as $15 billion. Then on Saturday, The Wall Street Journal, citing people familiar with the matter, reported that Prince Alwaleed would be joined by other investors, including the China Development Bank. The Journal reported it was unclear how much Prince Alwaleed would invest, but that the China Development Bank likely would contribute $2 billion.

The investments are expected to come as the bank is set to report fourth-quarter earnings expected to be weighed by a huge writedown tied to mortgages, leveraged loans, reserves and trading losses that may hit $24 billion next week.

Prince Alwaleed's potential investment would be Citi's second major cash infusion by the wealthy financier, who bailed out the bank back in 1991. Alwaleed is the single largest individual owner of Citi shares, but has a total stake less than 5%, which allows him to fall below the threshold requiring him to publicly file with the Securities and Exchange Commission. The investment amount reported by CNBC likely would drive him above that limit. The Journal's Saturday report said Citi was hoping to raise a total of $8 billion to $10 billion from multiple investors.

Financially troubled Wall Street firms such as Merrill Lynch ( MER) and Citi are desperate for fresh funds even after arranging billions in cash infusions from foreign investors because values in tens of billions of hard-to-value mortgages that they still hold on their books continue to shrink, traders tell TheStreet.com. Citi obtained $7.5 billion from Abu Dhabi Investment Authority, and Merrill received $6.2 billion from Singaporean fund Temasek and Davis Selected Advisors.

On Thursday, the Wall Street Journal reported that both Citi and Merrill were aggressively trawling for funds in the Middle East and in Asia, to steady their shaky balance sheets after already posting billions in writedowns. The report did not identify specific funding sources.

Citi could score as much as $10 billion from investors and Merrill could be obtaining $4 billion, the Journal noted Thursday.

Before the weekend, a Citi spokesman declined to comment on any reports, as did a Merrill spokeswoman.

Citi originally had been expected to take a writedown in the fourth quarter of less than half of what's being predicted now. Merrill is also slated to take a bigger-than-projected writedown of $15 billion on soured mortgages, according to a New York Times report Friday.

Citi's board also is expected to meet a day before it reports earnings on Jan. 15 to discuss cutting its dividend in half, the Journal said. The move, which Citi has repeatedly said it would not take, could save $5 billion, analysts have reported.

For Citi, the prospect of cutting its dividend and soliciting funds is déjà vu. About 17 years ago, Alwaleed invested $590 million in the bank, which at the time was known as Citicorp. That investment has earned Alwaleed billions, but the value of his stake has plunged in recent months in the wake of the departure of Citi's former CEO Charles Prince, who has been replaced by CEO Vikram Pandit and Chairman Win Bischoff.

CNBC's reports of the magnitude of Alwaleed's investment this time around, however, appear to be improbable, since it could raise the prince's investment to above 10%. At this point, the reported $15 billion investment alone would represent a 10% stake in Citi's outstanding shares.

U.S. government officials have been grousing about the large positions foreigners have taken in domestic financial institutions for fear of their political influence on the organizations, but the cash needs of Citi, Merrill and other financials appears dire.

Earlier in the month, Keefe, Bruyette analyst Diane Merdian estimated that Citi could face a $15 billion to $16 billion writedown, while Goldman Sachs' ( GS) William Tanona predicts a Citi writedown in the neighborhood of $19 billion.

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