• The Nasdaq Composite closed above 20,000 for the first time.
• Tesla shares hit a new all-time high.
• Apple integrated ChatGPT with its Siri assistant.

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

1. Twenty thousand

The Nasdaq Composite closed above 20,000 for the first time on Wednesday, ending the day 1.77% higher at 20,034.89. Tech stocks helped boost the index, as four of the sector's seven megacaps closed the day at all-time highs. The broad market S&P 500, meanwhile, added 0.82%, while the Dow Jones Industrial Average was the outlier, dropping 99.27 points, or 0.22%, for the day. The moves came after November's inflation report met economists' projections. Follow live market updates.

2. Tes-ooh la la

Tesla shares are on a tear. The EV maker's stock hit an all-time high Wednesday, closing at a new record of $424.77 and topping its last high set in 2021. Shares are up about 71% this year, and almost all of those gains have come since President-elect Donald Trump won the White House last month. Tesla CEO Elon Musk backed Trump in the campaign, putting $277 million into an effort to elect him. Musk — the world's richest man — has been increasingly close with Trump.

3. Supermarket spill

Albertsons is suing Kroger, accusing its supermarket competitor of violating a proposed $25 billion merger deal. The lawsuit, filed Wednesday, comes a day after a judge blocked the planned tie-up, which would have put nearly 40 supermarket chains — including Kroger's Fred Meyer and Albertsons' Safeway — under a single company. Albertsons formally terminated the proposal and said Kroger didn't follow through on commitments to help get the deal approved, violating its contract. The lawsuit is something of a corporate divorce battle, as the two sides argue about who should pay for the legal fees associated with the merger, as well as a potential breakup fee.

4. SiriGPT

Hey, Siri. Meet ChatGPT. Apple on Wednesday released the latest updates for its software, including a long-awaited integration that will bring OpenAI's ChatGPT to Apple's Siri assistant. That new artificial intelligence update will apply to iPhone, iPad and Mac software. ChatGPT will be triggered if a user asks Apple's assistant a complicated question. Apple said it has built privacy protections into the feature, which it is hoping will help will boost iPhone sales and drive an upgrade cycle.

5. 'Junior Mint'

JetBlue Airways is rolling out a domestic first class in 2026 on airplanes that don't have its top-tier "Mint" option. Mint has lie-back seats for longer international flights, but the airline said that same formula won't work on shorter flights, so it had to come up with a new concept for customers who are willing to pay for more room. "Since launching Mint over a decade ago, we've explored the idea of expanding a version of it across the fleet, often playfully calling it 'mini-Mint' or 'junior Mint,'" Marty St. George, JetBlue's president, said in a note to employees. It's the latest initiative for the carrier, which has been cutting routes to get back to profitability.

— CNBC's Sean Conlon, Lora Kolodny, Ari Levy, Melissa Repko, Kif Leswing, and Leslie Josephs contributed to this report.