WASHINGTON (AP) — The Federal Reserve took massive emergency action Sunday to try to help the economy withstand the coronavirus by slashing its benchmark interest rate to near zero and saying it would buy $700 billion in Treasury and mortgage bonds.

The Fed’s surprise announcement signaled its rising concern that the viral outbreak will depress economic growth in coming months, likely causing a recession, and that it’s poised to do whatever it can to counter the risks. It cut its key rate by a full percentage point to a range between zero and 0.25%.

Despite the move, Monday could be another bad day for the financial markets. On Wall Street, futures for the benchmark S&P 500 index fell 5% on Sunday night and triggered a halt in trading.

The central bank said it will keep its rate there until it is “confident that the economy has weathered recent events.”

The Fed’s surprise announcement signaled its rising concern that the viral outbreak will depress economic growth in coming months, likely causing a recession, and that it’s poised to do whatever it can to counter the risks. It cut its key rate by a full percentage point to a range between zero and 0.25%.

The central bank said it will keep its rate there until it is “confident that the economy has weathered recent events.”

The Fed will buy at least $500 billion of Treasury securities and at least $200 billion of mortgage-backed securities. This amounts to an effort to ease market disruptions that have made it harder for banks and large investors to sell Treasuries as well as to keep longer-term borrowing rates down.

All told, the Fed’s aggressive actions are intended to keep financial markets functioning and lending flowing to businesses and consumers. Otherwise, as revenue dries up for countless small businesses that have suddenly lost customers, these employers could be forced to lay off workers or even seek bankruptcy protection in some cases.

“This is a break-the-glass moment” for the Fed, said Mark Zandi, chief economist at Moody’s Analytics. “They are throwing everything they’ve got at this. My sense is they must be nervous about the credit system not functioning properly. They are trying to shore up confidence.”

By slashing its benchmark short-term rate and pumping hundreds of billions of dollars into the financial system, the Fed’s moves Sunday recalled the emergency action it took at the height of the financial crisis. Starting in 2008, the Fed cut its key rate to near zero and kept it there for seven years. The central bank has now returned that rate — which influences many consumer and business loans — to its record-low level.