Citigroup lined the $12.5 billion of capital through the sale of convertible preferred securities from several big investors, including two funds sponsored by cash-rich foreign governments. That comes on top of a $7.5 billion stake that the company sold to a Middle Eastern government fund, the Abu Dhabi Investment Authority, in November.

The Government of Singapore Investment Corporation will make a $6.88 billion investment, giving it one of the biggest ownership stakes in the company. The Kuwait Investment Authority, Capital Research and Management, Citigroup’s biggest shareholder, and the New Jersey Division of Investment also made large investments.

But the most interesting investments came from Mr. Weill and Prince Alwaleed bin Talal of Saudi Arabia, who met privately to discuss ousting Charles O. Prince III, Citigroup’s former chairman and chief executive, soon before he resigned in early November. Prince Alwaleed, who until recently had been Citigroup’s biggest shareholder, had bailed out the company from the real estate crisis in the early 1990s.

Mr. Weill, Citigroup’s former chairman who four years ago chose Mr. Prince as his successor, has complained his own personal fortune has been hurt by the bank’s poor performance and may see this as his own personal rescue mission. Both are also large existing shareholders and their actions will prevent their ownership stakes from being more severely diluted.

Citigroup announced other actions to strengthen its finances. It will offer public investors about $2 billion in newly issued debt securities, a portion of which will be convertible. It reduced the assets held on its balance sheet by $176 billion, or 7.4 percent, by shedding mortgage-backed securities and other assets held by both its consumer and investment banking businesses. And it sold ownership stakes it held in Redecard, a Brazilian company in the credit card industry, and an investment advisory arm of Nikko Cordial, a Japanese brokerage it agreed to buy last spring.

Citigroup’s board agreed to cut the stock dividend to 32 cents from 54 cents, reversing a position it staunchly held for the last few months. The reduction could free up $4.4 billion a year but could be a significant blow to big institutional shareholders and many retail investors, who bought Citigroup shares for their retirement accounts.

The latest moves highlight the extent to which Citigroup’s capital position has weakened and raise questions about the company’s diversified business model.