Citigroup Inc., taking another step to shrink its sprawling empire, plans to sell a large chunk of its minority stake in Brazilian credit-card company Redecard SA, according to people familiar with the matter.

Citigroup owns roughly 17% of Redecard's outstanding shares, which trade on the Sao Paulo stock exchange. The New York company plans to sell a portion of its stake to Brazil's Banco Itau, which is a co-owner of Redecard, say the people familiar with the matter. Citigroup is also preparing to sell some Redecard shares on the open market, the people say.

It isn't clear exactly how much of its Redecard stake Citigroup is planning to sell. Executives hope the transactions, which could be announced as early as next week, will generate up to $1 billion for the beleaguered bank, although one person cautioned that will depend on how much the shares fetch on the open market, the people familiar with the matter say.

A Citigroup spokeswoman declined to comment. An Itau spokesman had no immediate comment.

Citigroup's stock on Thursday tumbled 40 cents, or 14%, to close at $2.51 in New York Stock Exchange composite trading at 4 p.m., its lowest level since 1991. The stock's tailspin has intensified pressure on Citigroup to swiftly downsize and raise cash.

Since last fall, federal officials have been pushing Citigroup Chief Executive Vikram Pandit and his deputies to sell business lines that don't mesh with the company's core mission.

Citigroup's minority ownership of Redecard, and the fact that the company's shares are publicly traded, makes it a relatively easy candidate to sell in order to drum up cash.

Citigroup already has been whittling down its Redecard stake, which stood at about 31% in 2007. Since then, Citigroup has generated at least $1.4 billion by selling Redecard shares, according to regulatory filings. Redecard is jointly controlled by Citigroup, Itau and Unibanco, another Brazilian bank that Itau recently agreed to acquire.

Citigroup since last year has been reducing its exposure to Brazil. Still, the company recently completed its purchase of Brazilian retail brokerage firm Intra SA. That has raised eyebrows within Citigroup, since the company is trying to exit retail-brokerage businesses around the world.

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