US President Donald Trump and the Senate have agreed a massive economic relief package worth more than $1.8 trillion (£1.5tn).
The package includes money to bail out industries that have been affected by the coronavirus crisis.Republican Senate Majority leader Mitch McConnell described it as a "wartime level of investment" in the economy.
Markets surged in the US on Tuesday in anticipation of a deal, and shares rose in Europe and Asia on Wednesday.
On Wall Street, the Dow Jones jumped by 11.4% on Tuesday - its biggest one-day gain since the Great Depression.
Japan's benchmark Nikkei 225 index closed 8% higher on Wednesday following news of the relief deal.
Markets in Europe were also trading higher, with London's FTSE 100 index up 3.5%.
Full details of the deal agreed in the US will not be published until later on Wednesday. However, it is expected to contain measures to help people pay bills if they are laid off because of the virus, expand unemployment assistance by $250bn and get $350bn in emergency loans to small firms.Mr McConnell said it would also "stabilise" key industrial sectors and give money to hospitals and other healthcare providers which were having difficulty getting equipment.
"We're going to pass this legislation later today," Mr McConnell added.
Senate Democratic Leader Chuck Schumer called the package "the largest rescue package in American history". He said it was a "Marshall Plan" for hospitals. "Help is on the way, big help and quick help."
Separately on Tuesday, President Trump said he wanted to get the economy up and running again by Easter.
He said he was speaking to the Coronavirus Taskforce about when to open the US for business and that the Easter weekend -12 April - presented a "beautiful time, a beautiful timeline" and that he hoped to be able to open at least some sections of the country.