• Amazon told corporate workers to go to the office five days a week.
• Intel plans to turn its foundry business into a subsidiary and allow for outside funding.
• Boeing is freezing hiring and implementing other cost-cutting measures as more than 30,000 workers strike.

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

1. Such great heights

The Dow Jones Industrial Average hit a new all-time high on Monday, as the 30-stock index advanced 228.30 points, or 0.55%, for the day. The S&P 500 was just shy of its all-time high, adding 0.13% and closing at 5,633.09. The Nasdaq Composite, meanwhile, shed 0.52% as chip stocks, including Nvidia, fell. Apple shares dropped 2.8% as analysts suggested there could be less demand for iPhone 16 Pro models than expected. Follow live market updates.

2. Welcome to new working week

Amazon is saying goodbye to the hybrid working schedule. CEO Andy Jassy said Monday that corporate workers should be in the office five days a week starting Jan. 2. It's a significant shift from the previous requirement of being in the office three days a week. "Before the pandemic, it was not a given that folks could work remotely two days a week, and that will also be true moving forward — our expectation is that people will be in the office outside of extenuating circumstances," Jassy said in a memo. Amazon is aiming to streamline its corporate structure and eliminate bureaucracy by having fewer managers in each organization, he said. Also on Monday, hundreds of Amazon delivery drivers at a Queens, New York, facility joined the International Brotherhood of Teamsters in an escalation of organizing efforts.

3. Intel intel

Intel shares soared after hours on Monday as the company unveiled plans to turn its foundry business into an independent unit. It would have its own board and could potentially raise outside capital, Intel said. The restructuring is part of CEO Pat Gelsinger's plan to turn the chipmaker around and comes as Intel's stock has lost almost 60% of its value in 2024. The company has spent roughly $25 billion over the past two years on the foundry business, which Intel plans to use to manufacture chips for other customers. Intel also said Monday that it struck a deal with Amazon to produce custom chips for AI. It added that it would pause some efforts in Poland and Germany, but said U.S. manufacturing projects are unaffected.

4. Boeing freezes hiring

Boeing unveiled sweeping cost-cutting measures Monday as it deals with more than 30,000 factory workers in Washington and Oregon who went on strike last week. The manufacturer said it would implement a hiring freeze, put a pause on nonessential staff travel and reduce supplier spending to save money. CFO Brian West also told staff the company would make "significant reductions" to supplier spending and stop most purchase orders for its 737 Max, 767 and 777 jetliners. Boeing is not making funding cuts to safety, quality and direct customer support work, he added.

5. Charter's charm offensive

Charter Communications wants customers to view its cable and broadband provider in a more positive light. To that end, the company — which is known to customers under the name Spectrum — is rolling out new broadband, cable TV, and mobile bundles and pricing; increasing internet speeds; offering credits for service outages; and promising better reliability for customers. "It is hard to be loved when you're providing a critical service to the household that's a physical infrastructure that charges over $100 a month," Chris Winfrey told CNBC's Lillian Rizzo. The changes come as Charter and others in the industry deal with slowing broadband customer growth and continued defections from the cable TV bundle. Read more about Charter's plans here.

— CNBC's Hakyung Kim, Annie Palmer, Kif Leswing, Rohan Goswami, Leslie Josephs and Lillian Rizzo contributed to this report.