The Dow was the last to turn positive on Thursday, closing up more than a quarter of a percent, after an initial 800-point slide.

The S&P 500, which earlier this week slid into correction territory, gained 1.5% by the end of the day, after falling more than 2.5% in early trading.

And the Nasdaq soared after Biden's speech, finishing up a whopping 3.3% after losing about as much at the start of the session.

WealthWise Financial CEO, Loreen Gilbert, said given the escalation in Europe, it's possible the U.S. Federal Reserve might take a softer approach to raising rates.

"Pundits have been talking about what it would take to have this Fed put, and for the Federal Reserve to change their course from raising rates. And, so, the question here is: does this escalation cause the Fed to change their course. I think, a couple weeks ago, we were sitting at a very high probability of a 50 basis point increase in March and, now, that probability is going way down, and more towards that 25 basis points. So, that is going to appease the markets if, in fact, we do see either no rate increase - which I doubt that that's going to happen - but even a 25 basis point increase would appease the markets."

The whipsaw session reversed the fortunes of Tesla, shares of which were down as much as 8.4% but closed up nearly 5%. Earlier, the Wall Street Journal reported that the U.S. Securities and Exchange Commission is investigating whether recent stock sales Elon Musk and his brother "violated insider trading rules."

Shares of Apple were down more than 5% at its lows, but recovered to close up more than a percent and a half, climbing along with other megacaps including Amazon, Microsoft and Meta Platforms, which all saw big early losses but then finished up well over 4%. Microsoft closed up 5%.

But perhaps the most spectacular percentage spread during Thursday's wild session belonged to DraftKings, which started the day down more than 7% only to finish the session up 11.2%.