SAN FRANCISCO (MarketWatch) -- Countrywide Financial Corp. said Tuesday that it's not filing for bankruptcy as speculation swirls about the mortgage lender needing billions of dollars in extra cash to survive.

Shares of Countrywide slumped 28% to close at $5.47, the lowest level in more than a decade.

"There is no substance to the rumor that Countrywide is planning to file for bankruptcy," the company said in a statement emailed to MarketWatch.

Countrywide CFC, also said that it's not aware of any leading agencies that are considering downgrading the company's ratings.

As the largest mortgage lender in the United States, Countrywide has been hit hard by the subprime-fueled credit crisis. The company has stopped offering many types of more-profitable, riskier home loans and is focusing on selling mortgages that conform to the standards of government-sponsored enterprises like Fannie Mae FNM, +0.85% and Freddie Mac FRE, -0.64% . However, Fannie and Freddie have suffered big mortgage losses themselves in recent months.

"Countrywide is severely challenged and might falter if it does not receive an infusion of at least $4 billion within the next couple of weeks," Egan-Jones Ratings Co., a ratings agency, wrote in a note Tuesday. "The GSEs likely curtailing purchases have hurt Countrywide."

'Recreated' documents

Countrywide shares were also pressured after the New York Times reported that the company falsified some documents.

A la1`wyer for Countrywide told a judge recently that the lender "recreated" three letters related to the bankruptcy case of a Pennsylvania homeowner, the newspaper reported, citing court records. See related story.