Updated from Jan. 11Saudi 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.