The Russell 2000 index of smaller-company stocks picked up 45 points, or 3.6 percent, 1,312.
Stock markets around the world have seen significant gains after Wall Street rallied following a savage four-day rout, which was the worst-ever selloff before the holidays. Nasdaq rose 5.8 percent or 361 points to 6,554.
All told, the S&P 500 index rose 116.60 points, or 5 per cent, to 2,467.70. The call was a signal to the market, at least for a day, that Mnuchin perhaps knew something bad coming down the pike.
After a pause in trading for the holiday, USA markets reopen Wednesday.
Sentiment also improved after a Bloomberg News report said a US government delegation would travel to Beijing in early January to hold trade talks, the first face-to-face discussion since US President Donald Trump and Chinese President Xi Jinping agreed on a 90-day trade war truce. Amazon slid 5.2 percent to $1,395.
"Yes, of course, 100 percent", said Hassett, the chairman of the president's Council of Economic Advisers, when asked by reporters at the White House if Powell's job is safe.More news: 7-year-old who spoke with Trump still believes in Santa
More news: GoFundMe looks to raise money for 'ladders' at border wall
More news: Hector Bellerin: Arsenal defender out for 'some weeks'
Worldwide markets had been wobbling in the days before Christmas after Trump criticized Jerome Powell, the chairman of the US Federal Reserve. The stock market's super day comes after retailers posted the best holiday shopping season in six years. Before the recent bounce, the index fell 20 percent from its recent peak, slipping into a bear market.
All 11 sectors of the S&P 500 are now negative for December, the fourth quarter and the full year.
Analysts said that U.S. stocks are coming off of oversold conditions and are due for a bounce.
Adding to uncertainty, Reuters reported Trump is considering an executive order that would block U.S. companies from using equipment from China's Huawei Technologies and ZTE in the new year.
Following the opening bell, individual stocks getting battered included Viacom (4.1 percent), Conagra (3.1 percent), Campbell Soup Co. "We can assess the fundamental drivers, such as poor global economics, the Fed not altering its forward guidance or providing flexibility to the pace of balance sheet normalization, and ascertain nothing has really changed here", he added. "Oil prices have just moved quite markedly".
The offshore yuan was little changed after China released new rules promising to treat all companies equally, the latest positive step on the trade and investment front since further US and Chinese tariff hikes were paused. Brent crude, used to price global oils, lost 4.2 percent to $52.16 a barrel in London. Marathon Petroleum rose 1.9 percent to $55.36.
CURRENCIES: The dollar eased to 110.90 yen from 111.37 yen late Wednesday. Noble Energy slid 4.1 percent to $18.31. The euro weakened to $1.1387 from $1.1404.