Post shares fall 7% as the bird flu outbreak gets worse

Shares of Post Holdings are getting crushed after the company said the bird flu outbreak is hitting some of its farms.

There's a national outbreak of avian influenza, or bird flu, and it's believed to be the biggest ever recorded.

At least 15 states have now recorded infections, according to Reuters.

On Wednesday, shares of Post fell 7% to around $45.35 per share in early trading.

In a regulatory filing on Tuesday, the company said:

"Chicken flocks at company owned and third party farms in Nebraska and Iowa, respectively, have tested positive for AI. Including these two new incidents, Post now estimates that approximately 20% of its egg supply has been affected.

On May 7, 2015, Post provided Adjusted EBITDA guidance for fiscal 2015 of between $585.0 million and $610.0 million. This included an estimated negative impact of $20.0 million related to AI based on information available at that time. Post will update the estimated impact of AI as soon as practicable."

In an April 28 filing with the SEC, the company said that 10% of its egg supply had been impacted by the bird flu outbreak. In a May 7 filing, the company said 14% of its egg supply had been impacted.

Here's a chart showing the plunge in the share price: