LOS ANGELES — The credit mess forced Countrywide Financial Corp., the nation's largest mortgage lender, to borrow $11.5 billion yesterday, shocking financial markets already reeling from the growing credit crunch and threatening to make home loans harder to get.

Countrywide said it borrowed the cash from a group of 40 banks so it could keep making home loans.

The announcement sent its stock tumbling about 11 percent and prompted one credit rating agency to downgrade its rating to near-junk bond status.

Countrywide is the largest mortgage lender by volume, accounting for more than 13 percent of the loan servicing market as of June 30, according to the mortgage industry publication Inside Mortgage Finance.

It made the borrowing move amid a credit crunch that has driven a number of its smaller peers to bankruptcy.

Equity analyst Friedman, Billings, Ramsey Group Inc. said a continued liquidity crunch for more than three months could send Countrywide into bankruptcy.

Other analysts said the credit situation will have far-reaching consequences.

"We're in this situation where one of the biggest home lenders in the country is in significant financial difficulty and is being forced to take fairly extraordinary action to maintain its financial viability," said Tony Hughes, managing director of credit risk for Moody's www.Economy.com

"This means the threat of a credit crunch is very real. It means that mortgage finance generally will be hard to come by," he said.

Goldman Sachs analyst James Fotheringham said "it would not be in this country's best interest to have its largest mortgage lender cease operations." He did not elaborate.

Fotheringham said in a research note the country has yet to see the worst of the ongoing mortgage credit crunch.

"Industry trends are not improving," he wrote. "Home prices are 13 percent to 14 percent overvalued (which could take several years to play out)."

Some analysts said Countrywide had bought time with its huge loan.

John Kriz, a managing director of Moody's real estate finance team, believes Countrywide now has enough liquidity to meet debt obligations through 2008.

Countrywide President and Chief Operating Officer David Sambol said in a statement the company has "taken decisive steps which we believe will address the challenges arising in this environment and enable the company to meet its funding needs and continue growing its franchise."

The credit agreements require Countrywide to maintain a net worth of at least $7.68 billion and places some restrictions on the company, including limiting the amount of debt that its mortgage servicing unit can accrue to $100 million, according to Countrywide's filing with the Securities and Exchange Commission.

Homeowners who make their monthly mortgage payments to Countrywide should not be affected by the company's troubles, experts said.

Despite the company's assurances, its stock tumbled $2.34, to $18.95. The stock has lost more than half its value since January.

Credit rating agency Moody's Investors Service downgraded Countrywide's senior debt rating to "Baa3" from "A3," citing Countrywide's funding problems.

A ratings downgrade essentially makes it more expensive for a company to borrow money. Countrywide could be further downgraded if it continues to face liquidity problems, Moody's said in a statement.

The new rating is Moody's lowest investment-grade mark. Any downgrade would take Countrywide into "junk" status.