Stocks cratered Monday as investors grappled with the sinking price of oil and the spread of the coronavirus.

The Dow Jones Industrial Average tanked 1,229 points — 4.8% — on pace for its worst day since December 2008, while the S&P 500 plunged 5%. The massive sell-off triggered a key market circuit breaker minutes after the opening bell. Trading was halted for 15 minutes until reopening at 9:49 a.m. ET. At one point in morning trading, the 30-stock Dow dropped 2,046 points and the S&P 500 cratered 7.4%.

The sharp declines followed a roller-coaster week that saw the S&P 500 swing up or down more than 2.5% for four days straight. While Monday's drop was significant, it still didn't crack the 20 worst days for the S&P 500.

Investors continued to seek safer assets amid additional fears that the coronavirus will disrupt global supply chains and tip the economy into a recession. The yield on the benchmark 10-year Treasury note dropped below 0.5% for the first time ever, while the 30-year rate breached 1%. At one point early Monday, the 10-year slid to 0.318%.

Saudi Arabia on Saturday slashed official crude selling prices for April, in a sudden U-turn from previous attempts to support the oil market as the coronavirus hammers global demand. The move came after OPEC talks collapsed Friday, prompting some strategists to see oil prices crater to $20 per barrel this year.