Washington ? The Federal Reserve, in an extraordinarily rare weekend move, took bold action Sunday evening to provide cash to financially squeezed Wall Street investment houses, a fresh effort to prevent a spreading credit crisis from sinking the U.S. economy.

The central bank approved a cut in its emergency lending rate to financial institutions to 3.25 percent from 3.50 percent, effective immediately, and created a lending facility for big investment banks to secure short-term loans. The new lending facility will be available to big Wall Street firms today.

“These steps will provide financial institutions with greater assurance of access to funds,” Federal Reserve Chairman Ben Bernanke told reporters in a brief conference call Sunday evening.

The Fed acted just after JP Morgan Chase & Co. agreed to buy rival Bear Stearns Cos. for $236.2 million in a deal that represents a stunning collapse for one of the world’s largest and most venerable investment banks. Just on Friday the Fed had raced to provide emergency financing to cash-strapped Bear Stearns through JP Morgan. Days earlier the Fed announced a set of other unconventional steps to thaw out a credit market in danger of freezing shut.

“It seems as if Bernanke & Co. are pulling out all the stops to avoid a serious financial market meltdown,” Richard Yamarone, an economist at Argus Research, said Sunday evening.

On world financial markets, Asian stocks plunged early today after the JPMorgan and Fed announcements. Markets in Australia and New Zealand also fell.

The new lending facility – described as a cousin to the Fed’s emergency lending “discount window” for banks – is geared to give major investment houses a source of short-term cash on a regular basis – if they need it.

It will be in place for at least six months and “may be extended as conditions warrant,” the Fed said. The interest rate will be 3.25 percent and a range of collateral – including investment-grade mortgage backed securities – will be accepted to back the overnight loans.

Treasury Secretary Henry Paulson said he was pleased by Sunday’s developments.

“Last Friday, I said that market participants are addressing challenges, and I am pleased with recent developments. I appreciate the additional actions taken this evening by the Federal Reserve to enhance the stability, liquidity and orderliness of our markets,” he said.

“We appreciate the actions taken by the Federal Reserve this evening,” said White House press secretary Dana Perino. “Secretary Paulson and Chairman Bernanke are actively engaged in addressing issues affecting our financial markets. Secretary Paulson has kept the president briefed on recent developments.”

The “discount” rate cut announced Sunday applies only to the short-term loans that financial institutions get directly from the Federal Reserve. It doesn’t apply to individual borrowers.

The Fed’s actions are the latest in a recent string of innovative steps to deal with a worsening credit crisis that has unhinged Wall Street. And the action comes just two days before the central bank’s scheduled meeting on Tuesday, where another big cut to a key interest rate that affects millions of people and businesses is expected to be ordered. That key rate is now at 3 percent and is expected to be cut by at least one-half percentage point on Tuesday. Analysts said the Fed’s new steps may lessen pressure for a super-sized cut to that rate.