The Federal Reserve's balance sheet increased to a record $6.62 trillion this week as the central bank used its nearly unlimited buying power to soak up assets to keep markets functioning amid an abrupt economic free fall due to the coronavirus pandemic.

Since early March, the Fed has slashed interest rates to zero, restarted bond purchases and rolled out an unprecedented range of programs to keep credit flowing and shore up business and household confidence.

The central bank's balance sheet as of Wednesday rose about $200 billion from $6.42 trillion a week earlier. That is up from just $4.29 trillion in the first week of March.

It is now the equivalent of roughly 30% of the size of the U.S. economy before the crisis struck, and will certainly grow larger in the weeks ahead as the Fed keeps piling on assets and the economy shrinks.

The central bank continued to snap up Treasury securities, mortgage bonds and other assets, according to data released on Thursday. The Fed's holdings of mortgage-backed securities rose to $1.62 trillion from $1.57 trillion. Treasury holdings rose to $3.91 trillion from $3.79 trillion.

Use of the Fed’s central bank liquidity swap lines, which allow foreign central banks to exchange their local currencies for dollars, rose to $409.7 billion on Wednesday from $378.3 billion the previous week.

Loan balances for the Fed’s discount window, its last-resort lending program for banks, fell to $33.7 billion from $36.3 billion a week ago.

Loans with the Fed's primary dealer credit facility dipped to $31.5 billion from $33.4 billion the previous week. Use of the money market mutual fund liquidity facility slipped to $48.8 billion from $50.7 billion the week before.

The Commercial Paper Funding Facility II LLC, a special-purpose vehicle set up by the Fed with seed money from the U.S. Treasury, rose to $2.7 billion from $974 million on April 15. That facility began operations last week.

The newest item appearing on the Fed's balance sheet was loans it has taken on from banks participating in the Small Business Administration's "Payroll Protection Program," initially rolled out at $349 billion but set to be expanded under new appropriations from Congress after the original amount ran out in less than two weeks. The Fed held just over $8 billion of PPP loans as of Wednesday, an amount certain to rise in the coming weeks.

The Fed also said it will shortly announce new rules to expand access the PPP beyond banks, so that a broader set of institutions can participate. 

Meanwhile, the Federal Reserve had $85.8 billion in loans outstanding last week in three of the programs it rolled out last month to protect the economy during the coronavirus pandemic.

In a report to Congress that provided a look at the three programs as of April 14, it said Friday that it had $51.1 billion in loans outstanding for a program to support money market mutual funds and another $34.5 billion outstanding in loans to the giant Wall Street financial institutions that serve as primary dealers in the Treasury bond market.

For the third program, the Fed said it had $249 million in loans outstanding to support the commercial paper lending market.

In the first few weeks of operation, these programs had earned $39.4 million in interest and fees with no losses incurred, the Fed said.

The report on the three programs contained no names of the institutions receiving the loans.

The Fed announced on Thursday that it will provide monthly reports on other programs it has begun that will include the names of the institutions receiving the loans and the amount of those loans and the interest rates being paid.

Fed Chair Jerome Powell, in announcing this reporting effort, said the Fed was “committed to transparency and accountability” in the way it operates the various programs that are part of the $2 trillion rescue program approved by Congress last month.

That rescue effort has come under criticism after disclosures that some major publicly traded companies had obtained forgiveable loans from the government’s Paycheck Protection Program.

And the program quickly ran out of money, leaving many small and mid-size companies unable to obtain loans, a problem Congress sought to address with passage Thursday of another $484 billion in aid for small businesses, health care and virus testing.

Elsewhere, the benchmark rate targeted by the Federal Reserve fell to match its lowest ever level.

The effective fed funds rate fell to 0.04% Thursday from 0.05% the day before, according to New York Fed data released Friday. That’s in line with the low reached in 2011.

The Fed’s target range for the policy benchmark is 0%-0.25% and the effective rate can move around within that. The current effective rate is now six basis points below the interest on excess reserves rate -- presently 0.10% -- which is one of the tools the central bank uses to help steer front-end rates.

Fed policy makers are due to meet next week.

This report uses material from the AP, Bloomberg and Reuters.