April 30 (Reuters) - The Federal Reserve's balance sheet increased to a record $6.70 trillion this week, but the pace of expansion slowed dramatically as key credit markets have calmed since a firestorm of volatility sparked by the coronavirus pandemic drove the central bank to take emergency measures last month.
The central bank's balance sheet as of Wednesday was about $81.75 billion higher than the $6.62 trillion a week earlier, data released by the Fed on Thursday showed. It was the smallest increase in seven weeks and was just a fraction of the record $586 billion weekly increase in late March.
In all the Fed's stash of assets is up nearly 60% from just $4.2 trillion in early March, when it 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 as the outbreak forced a wave of stay-at-home orders across the country, torpedoing economic activity.
It is now the equivalent of more than 31% of the size of the U.S. economy at the end of the first quarter, and will certainly grow larger in the weeks ahead as the Fed keeps piling on assets and the economy shrinks further.
The U.S. economy contracted at a 4.8% annualized rate in the first quarter on the back of widespread shutdowns of nonessential business aimed at containing the spread of the disease. It may shrink at four times that rate or more in the second quarter with more than 30 million Americans thrown out of work since March 21.
As of Wednesday, the Fed's holdings of Treasury securities rose to $3.97 trillion from $3.91 trillion a week earlier. Mortgage-backed bond holdings were little changed at $1.60 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 $438.95 billion from $409.7 billion the previous week.
Loan balances for the Fed's discount window, its last-resort lending program for banks, fell to $31.8 billion from $33.7 billion a week ago.
(Reporting by Dan Burns; Editing by Sandra Maler and Daniel Wallis)
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