NEW YORK, New York - U.S. stocks roared back to life Thursday shrugging off concerns about the new Covid variant Omicron.

"While it is nice to see a rally, I am not sure investors should put much meaning into it," Jim Paulsen, chief investment strategist for Leuthold Group told CNBC Thursday.

"Fear and greed will dominate activity as investor worries oscillate between concerns the worst is not yet over and anxieties of missing out on any recovery," he said.

The Dow Jones Industrial Average regained 617.75 points or 1.82 percent to close Thursday at 34,639.79.

The Standard and Poor's 500 jumped 64.06 points or 1.42 percent to 4,577.10.

The technology-laden Nasdaq Composite added 127.27 points or 0.83 percent to 15,381.32.

The U.S. dollar was coma-like, barely moved from the prior day. The euro traded somewhat lower however at 1.1300. The British pound hovered around 1.3300. The Japanese yen was unchanged at 113.06. The Swiss franc similarly was unmoved at 0.9201.

The Canadian dollar changed hands at 1.2805. The Australian and New Zealand dollars each drifted a few points lower to 0.7092 and 0.6813 respectively.

The small-cap benchmark Russell 2000 climbed 2.7 percent.

Overseas, the FTSE 100 in London gave up 0.55 percent. The German Dax fell 1.35 percent. The Paris-based CAC 40 declined 1.25 percent.

On Asian markets, the Australian All Ordinaries lost 23.70 points or 0.09 percent to 7,536.10.

In Tokyo, the Nikkei 225 fell 182.25 points or 0.65 percent to 27,753.31.

China's Shanghai Composite barely moved, losing 3.5 points or 0.01 percent to 3,573.04.

The Hang Seng in Hong Kong let go 130.01 points or 0.55 percent to 27,788.93.