U.S. equity futures surged Friday morning, reaching the highest increases allowed outside regular trading hours, after both the Federal Reserve and the Bank of Japan pumped money into the financial system.

The major futures indexes -- for the Dow Jones Industrial Average, S&P 500 and Nasdaq -- are indicating a gain of 5 percent once regular trading starts.

Gains in such equity futures contracts have been capped at 5 percent during overnight trading under rules imposed after the "flash crash" of 2010.

The rallies suggest a sharp turnaround from Thursday, which saw Wall Street's biggest drop since the Black Monday crash of 1987.

Markets worldwide have retreated as fears of economic fallout from the coronavirus crisis deepen and the meltdown in the U.S., the world's biggest economy, batters confidence around the globe.

The sell-off on Wall Street helped to wipe out much of the big gains since President Trump took office. Read moreat FOX Business