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What: Shares of Hospira (NYSE: HSP) tanked today, down by as much as 22%, as the medical device and supply maker issued preliminary earnings and cut its full-year earnings guidance.

So what: The company expects a GAAP loss of $0.54 per share, compared with the prior year's $0.42 profit. Going forward, Hospira said it expects adjusted full-year earnings to be in the range of $2.95 to $3.05, far lower than its previous guidance of $3.90 to $4 and the consensus estimate of $3.91.

Now what: Hospira attributed the weakness to actions taken in response to an investigation conducted by the U.S. Food and Drug Administration regarding the company's plant in Rocky Mount, N.C., concerning quality and supply issues. Hospira CEO Michael Ball said, "We are extremely disappointed in the third quarter by the developments related to our quality-improvement initiatives." The plant in question produces roughly a quarter of the company's revenue, so the developments are definitely weighing on the bottom line.

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Fool contributor Evan Niu holds no position in any company mentioned. Check out his holdings and a short bio. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.