• The Dow Jones Industrial Average posted its largest intraday swing ever recorded.
• Markets are hanging on any indication that Trump will soften his tariff plan.
• Apple stock has found itself in the crosshairs. The company's market cap has fallen $638 billion in three trading days.

Here are five key things investors need to know to start the trading day:

1. Broken records

The Dow Jones Industrial Average posted its largest intraday swing ever recorded Monday, gaining 2,595 points from low to high during a wild session. The index ultimately ended the day about 349 points, or 0.9%, lower as President Donald Trump's aggressive tariff policies dented stocks for a third day. The S&P 500 fell more than 0.2% after shedding as much as 4.7% during the session and briefly entering bear market territory. The Nasdaq Composite managed a positive day, gaining 0.1% as investors found solace in megacap tech. By Tuesday morning, stock futures were back on the rise. Follow live market updates.

2. The art of the deal

To negotiate or not to negotiate — that seems to be the question. Markets are hanging on any indication that Trump will soften his tariff plan, with Treasury Secretary Scott Bessent saying the White House is prepared to hold "meaningful negotiations" with upwards of 50 countries that have responded "positively" to Trump's trade policies. Bessent said he expects Japan to be first in line at the table, but the process could take some time. "It's going to be a busy April, May, maybe into June," he told Fox Business. Follow live updates on Trump's tariff rollout.

3. Recession rhetoric

Will Trump's tariffs usher in a full-scale recession? If you ask Wall Street economists, the answer is they could. If you ask members of CNBC's CEO Council, the answer is a more resounding yes, according to 69% of CEOs surveyed in the days after Trump's plan was announced. Ask Larry Fink, CEO of BlackRock, and the answer is a recession is already here: "Most CEOs I talk to would say we are probably in a recession right now," Fink said Monday during an event at the Economic Club of New York. "One CEO specifically said the airline industry is a proverbial bird in a coal mine — canary in the coal mine — and I was told that the canary is sick already."

4. Apple a day

Apple stock has found itself in the crosshairs of a trade war. The company's market cap has fallen $638 billion in three trading days, shedding about 19% of its value. Apple's supply chain is heavily reliant on China, with additional production in India, Vietnam and Thailand. All four countries face steep tariffs under Trump's plan. Analysts expect Apple may be forced to raise prices for consumers to offset the impact of tariffs.

5. In the club

Walmart's membership service is looking stronger — at a crucial time. The retailer told CNBC that Walmart+ customers accounted for almost half of all spending across Walmart's online channels in the U.S. during the last fiscal year. Those subscribers also shopped more — twice as often, and spending nearly three times as much — as non-members. It's a sign of strong momentum as Americans increasingly hunt for convenience and lower prices. Walmart is hosting an investor event in Dallas starting Tuesday, where it will likely address the health of the consumer and the recent trade developments.

Correction: An earlier version of this article misstated the network Treasury Secretary Scott Bessent spoke on; it was Fox Business.

– CNBC's John Melloy, Hakyung Kim, Tanaya Macheel, Erin Doherty, Jesse Pound, Jeff Cox, Eric Rosenbaum, Kif Leswing and Melissa Repko contributed to this report.