The stock market is trading lower midday, heading towards the third consecutive day of decline.

The S&P 500 lost 1.12%, and the tech-heavy Nasdaq Composite fell 1.87%. The Dow Jones Industrial Average slid 1.03%, and the Russell 2000 Index was down 1.02%.

All the Magnificent 7 stocks are down midday. Tesla fell 2% before its quarterly earnings, which will come out later today.

S&P 500 big stock movers today

Five S&P 500 stocks making big midday moves are:

• Northern Trust  (NTRS)  +7.8%

• Packaging Corp of America  (PKG) +5.7%

• Teledyne Technologies  (TDY)  +4.9%

• AT&T  (T) +4.1%

• Texas Instruments  (TXN)  +3.8%

The worst-performing five S&P 500 stocks with the largest midday drop are:

• Enphase Energy  (ENPH)  -14.6%

• CoStar  (CSGP)  -8.6%

• Seagate Technology  (STX)  -7.5%

• McDonald’s  (MCD)  -5.3%

• Old Dominion Freight Line  (ODFL)  -5.0%

Stocks also worth noting include:

• Nvidia  (NVDA)  -3.6%

• Tesla  (TSLA)  -2.2%

• Apple  (AAPL)  -2.7%

• Coca-Cola  (KO)  -1.7%

• Starbucks  (SBUX)  -0.2%

McDonald’s falls on E. coli outbreak

McDonald’s shares dropped 5% midday after the CDC linked an E. coli outbreak to the chain’s Quarter Pounder burgers, resulting in 10 hospitalizations and one death.

The CDC reported 49 cases across 10 states, with most in Colorado and Nebraska.

Related: McDonald's president flags a worrisome trend, shifting outlooks

The outbreak may be tied to slivered onions used in the burgers, sourced from a single supplier.

McDonald’s has removed slivered onions from affected locations and paused distribution in the impacted areas. The company said it’s taking “swift and decisive action” as the investigation continues.

Starbucks slides on preliminary earnings

Starbucks dipped 0.2% after issuing preliminary quarterly results that showed another sales fall.

The coffee chain reported a 3% drop in sales for the quarter as it struggled to reverse declining demand. Its new CEO, Brian Niccol, who recently left Chipotle Mexican Grill, said the "Back to Starbucks" plan will focus on returning to growth.

Related: Analysts revise Chipotle stock price targets after CEO's startling exit

Niccol plans to reveal more details during the Oct. 30 earnings call and is already refocusing marketing, simplifying the menu, and addressing pricing issues. The company also plans to suspend guidance for fiscal year 2025.

Same-store sales fell 7%, the steepest drop since the pandemic. The company attributed its weak performance to reduced demand in North America.