• Futures are trading higher Monday morning, led by the tech sector.
• It's the busiest week of Q3 earnings.
• McDonald's is reinstating the Quarter Pounder after it pulled the menu item from certain locations following a deadly E. coli outbreak.

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

1. Tech leads

Futures are trading higher Monday morning, led by the tech sector. Futures tied to the Dow Jones Industrial Average gained 0.5%, S&P 500 futures rose 0.6%, and Nasdaq 100 futures advanced 0.8%. The tech-heavy Nasdaq Composite closed out a winning week on Friday with a new intraday all-time high. Meanwhile, the Dow and S&P fell on Friday and each snapped six-week winning streaks. With just four trading sessions left in the month, the Dow is down 0.5% for October, the S&P is up 0.8%, and the Nasdaq is up 1.8%. Follow live market updates.

2. Peak week

It's the busiest week of Q3 earnings. More than 150 S&P 500 companies are set to report, spanning tech, autos, restaurants, oil and pharma. Here are some of the most-anticipated earnings reports due out this week:

• Monday: Ford (after the bell)
• Tuesday: McDonald's, Pfizer (before the bell); Alphabet, AMD, Chipotle, Reddit, Snap (after the bell)
• Wednesday: Biogen, Eli Lilly (before the bell); Meta, Microsoft, Starbucks (after the bell)
• Thursday: Bristol Myers Squibb, Comcast, Merck, Peloton, Uber (before the bell); Amazon, Apple, Intel (after the bell)
• Friday: Chevron, Exxon Mobil (before the bell)
• Saturday: Berkshire Hathaway

3. Court strike

Delta Air Lines is suing CrowdStrike after a July software outage led to thousands of canceled flights. The complaint accuses CrowdStrike of breach of contract and negligence and seeks damages in the hundreds of millions of dollars to cover Delta's losses along with litigation costs and punitive damages. "CrowdStrike caused a global catastrophe because it cut corners, took shortcuts, and circumvented the very testing and certification processes it advertised, for its own benefit and profit," Delta said in its complaint. A spokesperson for CrowdStrike said in a statement the claims are "based on disproven misinformation, demonstrate a lack of understanding of how modern cybersecurity works, and reflect a desperate attempt to shift blame for its slow recovery away from its failure to modernize its antiquated IT infrastructure."

4. Quarter Pounders return

McDonald's is reinstating the Quarter Pounder after it pulled the menu item from certain locations following a deadly E. coli outbreak. The burger will return to roughly 3,000 restaurants — about a fifth of the company's footprint. About 900 of those restaurants will serve the burgers without slivered onions for the time being. "The issue appears to be contained to a particular ingredient and geography, and we remain very confident that any contaminated product related to this outbreak has been removed from our supply chain and is out of all McDonald's restaurants," Cesar Pina, chief supply chain officer for McDonald's North American operations, said in a letter Sunday. The impacted restaurants are in Colorado, Kansas and Wyoming as well as portions of Idaho, Iowa, Missouri, Montana, Nebraska, Nevada, New Mexico, Oklahoma and Utah.

5. Peddling bikes

David Einhorn is making his pitch for Peloton. The hedge fund manager last week said the fitness company's shares could trade as high as $31.50, roughly five times their current levels of roughly $6.30 apiece. Einhorn's investment thesis was based on Peloton boosting EBITDA without growing subscription revenue or raising prices for users. "Peloton has started to right-size and cash burn has stopped. It refinanced its debt to push out maturities. And with a loyal customer base that pays $44 per month, it's a valuable subscription business," Einhorn said during his pitch, which he made while riding one of the company's bikes.

– CNBC's Tanaya Macheel, Fred Imbert, Jordan Novet, Leslie Josephs, Amelia Lucas and Gabrielle Fonrouge contributed to this report.

Clarification: This story has been updated to clarify that McDonald's is returning the Quarter Pounder to roughly 3,000 locations after pulling the menu item following an E. coli outbreak. About 900 restaurants will serve the burgers without slivered onions.