Five months after restarting a bond-buying program last used in the financial crisis, the Federal Reserve has purchased about $892 billion of agency mortgage-backed securities, according to a Fed blog post on Thursday.

The asset-buying has helped to drive mortgage financing costs to the lowest level ever recorded, with the average U.S. 30-year fixed rate hitting new lows eight times so far in 2020, according to weekly data from Freddie Mac. When there is competition for mortgage bonds, investors have to take smaller yields, which translates into lower interest rates for consumers.

Mortgage rates dropped to an all-time low of 2.88% in the first week of August, according to Freddie Mac. The rate has inched up since then, reaching 2.99% this week as investors worried about a protracted recession following a worsening of the COVID-19 pandemic.

In mid-March, when the Fed began buying bonds, the 30-year fixed rate as measured by Freddie Mac was 3.65%.

The Fed bought about twice as many Treasuries as MBS, according to the blog post’s tally. Cumulative purchases of Treasuries between March 13 and July 31, the same period used for the MBS total, amounted to $1.77 trillion. Treasury yields are used as benchmarks for MBS investors, so those purchases would have put downward pressure on home-loan rates, as well.

In March, the markets for Treasuries and agency MBS became “severely impaired” as investors reacted to the onset of the pandemic in the U.S., Lorie Logan, a Federal Reserve Bank of New York vice president, said in a July speech cited in Thursday’s blog post. If the Fed hadn’t responded “quickly and decisively” the credit markets would have seized up, she said.

“Given the importance of these markets, continued dysfunction would have led to an even deeper and broader seizing up of credit markets and ultimately worsened the financial hardships that many Americans have been experiencing as a result of the pandemic,” Logan said.

At the Fed’s June meeting of the rate-setting Federal Open Market Committee, policymakers committed to continuing the purchases at a level of about $80 billion per month in Treasuries and about $40 billion per month, net of reinvestments, in MBS.

“Although market functioning has improved markedly since the period of extreme stress in mid-March, uncertainty about the course of the pandemic makes it prudent to protect against further shocks,” Logan said. “Purchases over coming months will help mitigate risks of renewed stress and sustain continued smooth market functioning.”