"This is a fast-moving outbreak investigation," the CDC wrote on its website. "Most sick people are reporting eating Quarter Pounder hamburgers from McDonald’s and investigators are working quickly to confirm which food ingredient is contaminated."
The CDC said McDonald’s has stopped using fresh slivered onions and quarter-pound beef patties in certain states while a source of the illness is confirmed.
One person has died from the outbreak, the agency said, and 10 hospitalisations have been reported across 10 states.
McDonald's chief supply chain officer of North America Cesar Piña said in an internal memo shared on the company's website on Tuesday evening that it was taking "swift and decisive action" and noted that the initial findings from the investigation "indicate that a subset of illnesses may be linked to slivered onions used in the Quarter Pounder and sourced by a single supplier that serves three distribution centers."
Electric carmaker Tesla saw little movement in pre-market trading on Wednesday morning, ahead of the release of the company's third-quarter earnings later in the day.
Investor attention is is particularly focused on this report, as the stock slumped after Tesla's recent robotaxi event.
However, recently released figures showed that Tesla's deliveries were up 6% for the third quarter.
AJ Bell's Russ Mould, Danni Hewson and Dan Coatsworth said that this had that this "understandably led analysts to expect better again for the third quarter" results more broadly.
They said analysts were expecting sales to come in at $25.5bn (£19.6bn) for the third quarter, which would be 9% higher than a year ago.
Analysts are also said to be expecting to see further improvement in earnings per share (EPS) of $0.57 in the third-quarter, which would mean a return to year-on-year growth.
Shares in Starbucks fell 5% in pre-market trading on Wednesday, after the company reported declines in revenue and earnings in its preliminary results, and suspended its full-year guidance.
The coffee shop chain posted a 3% fall in revenue year-on-year to $9.1bn in preliminary four-quarter results released on Tuesday afternoon, along with a 24% drop in earnings per share to $0.80.
Starbucks also suspended its full-year fiscal 2025 guidance, citing its transition to new CEO Brian Niccol and to allow time to re-strategise.
US same-store sales were down 6% year-on-year in Q4, with a 10% decline in foot traffic and a 4% increase in the average ticket. Meanwhile, Starbucks China's same-store sales fell 14%, with a 6% drop in foot traffic and an 8% decline in the average ticket size.
The company attributed the performance to "intensified competition and a soft macro environment that impacted consumer spending."
Singer Anitta walks the runway during 'Le Défilé L'Oréal Paris — Walk Your Worth' Womenswear Spring-Summer 2025 show as part of Paris Fashion Week. ·Stephane Cardinale - Corbis via Getty Images
Despite reporting overall growth in sales in the third quarter, L'Oréal said sales had fallen in its North Asia business, dragging shares down 3% into the red on Wednesday morning.
The French cosmetics company reported sales of €10.3bn (£8.5bn) in the third quarter, which was up more than 3% from the same period last year.
However, L'Oréal said sales had declined 6.5% in its North Asia business to just under €2bn for the period.
Nicolas Hieronimus, CEO of L'Oréal, said: "As anticipated, global beauty market growth has been normalising throughout the year."
"The situation in the Chinese ecosystem has become even more challenging, but we believe in the future of this market and hope that the governmental stimulus will help improve consumer confidence," he added.
David Thomas, CEO of Barratt Redrow, said: "We begin this journey with a strong balance sheet, a solid forward sales position and the ability to add significant value through cost and revenue synergies. We look forward with confidence to delivering a smooth and efficient integration process, and to capturing the enhanced growth opportunities ahead of us.”
Russ Mould, investment director at AJ Bell, said the "market has still given the business some credit for the news", with shares up nearly 3% on Wednesday morning.
"The savings look meaningful but not so unrealistically high that management are setting themselves up to fail or mindlessly slashing costs with a potential knock-on effect on business performance," he said.
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