Wall Street has suffered its worst trading day since 1987 despite a massive liquidity injection by the Federal Reserve, as markets grimly assess the potential economic fallout from the coronavirus pandemic.

The Dow Jones Industrial average was down 2,352.75 points, or 9.99 percent, to 21,200.47 at the closing bell on Thursday.

It was the index's largest percentage drop since the Black Monday crash of 1987, and its largest point drop of all time, beating the record set earlier this week.

Just five minutes into Thursday's session, trading was temporarily halted for an unprecedented second time in one week, after the S&P 500 plunged 7 percent and triggered Wall Street's 'circuit breaker'. 

The S&P 500 and the Nasdaq Composite both ended the session down more than 9 percent, and officially joined the Dow in a bear market, down well more than 20 percent from recent peaks set just last month.