That's the end of regulation. Clean Harbor is ringing the closing belt, the New York Stock Exchange, Global Eid doing the honors at the NASDAQ.

Another roller coaster session as the market reacts to fast-moving tariff and trade developments,

with stocks closing off the lows on late-breaking headlines from the lows to the highs for the S&P,

nearly 2% move today, but fading again into the close here.

That's the scorecard on Wall Street, but the action is just getting started.

Welcome to closing bell overtime. I'm Morgan Brennan at CNBC headquarters.

Coming up in just a moment, White House Senior Council for Trade and Manufacturing, Peter Navarro,

is going to join us in a first on CNBC interview to talk about the trade developments

between the U.S. and Canada and more.

Plus, John Fort is at South by Southwest in Austin, Texas, where he will be joined shortly

by a special guest, John.

That's right.

Morgan, IBM CEO, Arvin Krishna, is here.

We just did a little conversation here in a keynote today at South by Southwest.

We're going to talk about the White House. He was there yesterday with President Trump.

Also talk about the impact of tariffs and this market turmoil on the business of technology companies, AI, quantum, and more.

All right, we're looking forward to that, John.

We're going to see in just a little bit.

We begin, though, with the tariff news that shaped the trading day, again.

Stocks fell mid-session after President Trump said he would double the tariffs on Canadian steel and aluminum to 50%.

That was in response to Ontario's move to place a 25% tax on electricity exports to the United States.

But we came off the lows after Ontario's premier said the electricity surcharge would not take effect.

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