• JPMorgan Chase CEO Jamie Dimon said he wouldn't rule out the idea of stagflation.
• Southwest Airlines executive chairman and former CEO Gary Kelly will step down next year.
• Presidential candidates Donald Trump and Kamala Harris sparred at their first debate.

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

1. Inflation watch

The S&P 500 climbed for the second day in a row, adding 0.45% on Tuesday. The Nasdaq Composite also rose for the day, gaining 0.84%, thanks to a boost from tech stocks Nvidia, AMD and Microsoft. The Dow Jones Industrial Average turned in the opposite direction, slipping 92.63 points, or 0.23%. Investors will watch Wednesday for the first of two key inflation reports as the Labor Department is set to release its consumer price index report for August. Follow live market updates.

2. Banking on it

It was a big day for the biggest bank. JPMorgan Chase shares fell 5% on Tuesday as President Daniel Pinto told analysts at a financial conference that expectations for 2025 net interest income and expenses — one of the main ways banks make money — were too high. Meanwhile, JPMorgan CEO Jamie Dimon said at a separate conference that he wouldn't rule out the idea of stagflation, which he said would be the "worst outcome." Both leaders' comments came as a top Federal Reserve official on Tuesday unveiled toned-down banking regulations that would roughly cut in half the extra capital that the biggest banks would be forced to hold under a regulatory overhaul. That move would be a victory for Wall Street, which has said the previous requirements were too onerous.

3. Change in the air

Southwest Airlines executive chairman and former CEO Gary Kelly will step down next year and the company will shake up its board, the carrier said Tuesday. Kelly has spent nearly 40 years at Southwest and held the role of chairman since co-founder Herb Kelleher retired in 2008. The moves come as the airline faced pressure from activist investor Elliott Investment Management, which revealed a nearly $2 billion stake in Southwest in June. Kelly also said six of Southwest's board members will retire in November and the company will appoint four new independent directors.

4. From screen to cart

There's a whole new lens coming to the 2024 MTV VMAs on Wednesday night. MTV's parent company Paramount Global has teamed up with shoppable advertising company Shopsense AI so viewers can shop the red carpet looks they're seeing in real time. The startup has an AI-powered lens that lets viewers point their camera at their TV screen and browse similar options suggested by Shopsense's product recognition algorithm. Since most celebrities will be wearing custom looks on Wednesday, the software will suggest so-called dupes at a variety of price points. Every time someone buys something based off of the lens' suggestions, Paramount will get some revenue, Shopsense said. Read more about the partnership here.

5. Debate

Presidential candidates Donald Trump and Kamala Harris faced off in their first debate on Tuesday evening. Ahead of the meeting, polling averages indicated the race was effectively tied at the national level. Harris provoked Trump throughout the debate — which quickly launched into a bitter, fast-moving, energized and occasionally angry back-and-forth — and focused her early remarks on the economy. Trump, meanwhile, turned his attention to immigration and emphasized a false conspiracy theory about immigrants stealing and eating people's pets. Shortly after the debate, pop megastar Taylor Swift endorsed Harris for president, while taking a swipe at Trump's Republican ticket running mate, Sen. JD Vance of Ohio.

— CNBC's Pia Singh, Hugh Son, Sarah Min, Leslie Josephs, Rohan Goswami, Gabrielle Fonrouge, Lillian Rizzo, Dan Mangan, Kevin Breuninger, Josephine Rozzelle, Rebecca Picciotto, Ece Yildirim and NBC News contributed to this report.