Key Takeaways Shares in McDonald’s slumped 6% in extended trading on Tuesday after health authorities said they were investigating an E. coli outbreak possibly linked to the fast-food chain’s Quarter Pounder burgers.

An outbreak of E. coli linked to McDonald’s Corp. Quarter Pounder burgers has killed one person and hospitalized 10 people in 10 states.

The day after Trump was seen serving fries at a Pennsylvania McDonald's, the company's stock dropped by 0.53 percent.

Shares of McDonald’s plummeted in extended trading on Tuesday after U.S. health authorities said they were investigating an E. coli outbreak possibly linked to the burger chain’s Quarter Pounder.

McDonald's shares fell 5.9% in afterhours trading following reports that the chain's Quarter Pounder hamburgers have been linked to an E. coli outbreak that has sickened at least 49 people and killed one,

McDonald’s (MCD) stock plunged as much as 10% afterhours on Tuesday when the Centers for Disease Control (CDC) said that the burger chain had caused an outbreak of E. coli in the middle of the country. MCD stock dove from above $314 to the $280s but then recovered close to $296, down 5.8%, by the close of the afterhours trade.

Nearly 50 people in nearly one dozen states have fallen ill as the result of an E. coli outbreak tied to McDonald's Quarter Pounders, the CDC said Tuesday.

At least one person has died and 49 were sickened in connection with the outbreak, according to the CDC. The stock was down more than 9% after hours.

The Centers for Disease Control and Prevention and other federal agencies are investigating an E. coli outbreak linked to McDonald’s quarter pounders, sending McDonald’s stock down nearly 9% in after-hours trading.