• Stocks fell again Thursday.
• China raised tariffs on U.S. products to 125% from 84%.
• Big banks started reporting earnings.

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

1. The Dow Jones

Stocks on Thursday gave back some of the gains from the previous day's historic rally. The Dow Jones Industrial Average dropped 1,014.79 points, or 2.5%, while the S&P 500 lost 3.46% and the Nasdaq Composite sold off 4.31%. Tech stocks led some of the slide, as Apple fell 4.2%, Tesla pulled back 7.3%, Nvidia dropped nearly 6% and Meta Platforms sank almost 7%. Follow live market updates.

2. Pause and effect

President Donald Trump declined to rule out extending the 90-day tariff pause he implemented this week. He told a reporter in a Cabinet meeting that if he can't reach the deals he wanted to with other countries, he might go back to the higher tariff rates. But when asked if that means he would not extend the pause, Trump said, "We'll have to see what happens." The White House also confirmed to CNBC on Thursday that the U.S. tariff rate on Chinese imports now effectively totals 145%, with the latest executive order raising the rate to 125% on top of a 20% fentanyl-related tariff that Trump previously implemented. China retaliated by raising its levies on U.S. products to 125% from 84%. Investors have been worried that even with a short pause in the duties, Trump's singling out of China will slow economic activity.

3. Amazon considerations

Amazon CEO Andy Jassy said the company is still figuring out how Trump's tariffs will affect its business, but he believes third-party sellers may "pass that cost on" to consumers. Amazon started to cancel some direct import orders for products sourced by vendors in China after the tariffs announcement, consultants told CNBC. Jassy also released his annual shareholder letter Thursday, which didn't mention tariffs but said the company has done some "strategic forward inventory buys" and is trying to renegotiate terms on some purchase orders to keep prices low.

4. Big bank earnings

JPMorgan Chase topped quarterly expectations, but CEO Jamie Dimon said the U.S. economy is facing "considerable turbulence." Wells Fargo, meanwhile, reported stable income from investment banking and wealth management, but CEO Charlie Scharf called for a "timely" trade resolution. And Morgan Stanley topped quarterly estimates on stronger-than-expected stock trading.

5. MLB valuations

The average Major League Baseball team is worth $2.62 billion, according to CNBC's Official MLB Team Valuations 2025. The most valuable team is the New York Yankees, worth $8 billion, ranking only behind the NFL's Dallas Cowboys and the NBA's Golden State Warriors among all North American sports franchises. See the full MLB valuations here.

— CNBC's Hakyung Kim, Dan Mangan, Kevin Breuninger, Christina Wilkie, Megan Cassella, Jesse Pound, Annie Palmer, Hugh Son, Yun Li, Michael Ozanian and Ruxandra Iordache contributed to this report.