• Dow futures were down more than 1,000 points after President Donald Trump announced higher-than-expected tariffs.
• Tesla shares rose after reports that CEO Elon Musk may soon leave his White House role.
• Amazon and AppLovin joined the bidding war for TikTok.

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

1. Tariff tumble

Stock futures plummeted after President Donald Trump shocked investors by announcing higher-than-expected tariffs Wednesday afternoon. Futures tied to the Dow Jones Industrial Average dropped 1,064 points, or 2.5%, while Nasdaq-100 futures sank 3.4% and futures tied to the S&P 500 slid 3.1%. But Treasury Secretary Scott Bessent pushed back on the idea that Trump's policies are behind the market sell-off, pointing instead to a pullback in big tech stocks. "What I would point out is that especially the Nasdaq peaked on DeepSeek day, so that's a Mag 7 problem, not a MAGA problem," he said Wednesday night. Follow live market updates.

2. Across the board

The United States will levy a 10% baseline tariff on all imports and steeper rates on many countries, President Trump announced Wednesday. The "reciprocal tariffs" plan includes duties of 20% on the European Union, 32% on Taiwan, 34% on China and 46% on Vietnam, all taking effect in the coming days. The White House said the higher, country-specific tariff rates were roughly half of what it claimed each country has "charged" the U.S. But market observers quickly reverse engineered the figures, to confusing results.

3. Fighting back

Countries around the world are weighing their next steps in the wake of Trump's fresh tariffs, with many vowing to retaliate. "We are prepared to respond," European Commission President Ursula von der Leyen said. "We are now preparing for further countermeasures, to protect our interests and our businesses if negotiations fail." China's Ministry of Commerce, meanwhile, urged the U.S. to "immediately cancel" the new tariffs, promising to take "resolute countermeasures."

4. Done with DOGE?

Tesla shares had a wild ride on Wednesday. The stock dipped in the morning on the back of weaker-than-expected vehicle deliveries, then rallied on reports that CEO Elon Musk may soon leave his White House role, only to sink again following Trump's tariff announcement. The EV maker on Wednesday reported 336,681 deliveries in its first quarter — a 13% decline from a year ago — amid protests and boycotts against Musk's role in the Trump administration. But Musk may soon be on his way out of the White House: Trump recently told his Cabinet members that the CEO will leave the administration in the coming months, according to NBC News. Tesla shares closed the day up more than 5% on the news, but the gains were largely wiped out by the post-tariff announcement sell-off. Shares were last down 6% premarket.

5. Bidding war

Bidders are lining up for TikTok as the deadline nears for ByteDance to divest the popular social media app's American operations. CNBC confirmed that Amazon this week submitted a bid for the app, sending its proposal in a letter to Vice President JD Vance and Commerce Secretary Howard Lutnick. Ad tech company AppLovin is also in negotiations to potentially acquire TikTok, sources told CNBC's David Faber Wednesday. But the clock's ticking. TikTok faces another potential shutdown on April 5 unless ByteDance agrees to divest the app's American operations, though Trump has indicated he might extend the deadline.

— CNBC's John Melloy, Pia Singh, Yun Li, Dan Mangan, Kevin Breuninger, Jesse Pound, Christina Wilkie, Megan Cassella, Erin Doherty, Neelabh Chaturvedi, Asriel Chua, Sophie Kiderlin, Lim Hui Jie, Anniek Bao, Lora Kolodny, Fred Imbert, CJ Haddad and Annie Palmer contributed to this report.