What happened

Shares of public health threat neutralizer Emergent Biosolutions (NYSE:EBS) fell nearly 12% today for, well, no compelling reason at this time. Sometimes stocks go up, and sometimes they go down. But it's important to remember that single-day movements have little effect on the long-term performance of a company. 

So what

If you really wanted to reach, then there is some news in the company's field. Researchers at the University of Nebraska-Lincoln reported that an experimental flu vaccine could provide lifetime immunity to influenza strains. In other words, a universal flu shot.

A businessman holding out his hand with a bar stock chart showing losses hovering over it.

Image source: Getty Images.

Except, of course, the results were only reported in a study concerning mice, which means it's far too early to assume the universal flu vaccine would work in humans. Many scientists have been hunting for such a treatment for decades.

It's also extremely unlikely to have an effect on Emergent Biosolutions, which only has flu vaccines in its pipeline at the moment. Through the first nine months of this year, nearly 70% of its product revenue was generated from its anthrax product, which is mostly sold to the U.S. government. 

Shareholders certainly never want to see their holdings decrease by double digits, but this seems relatively innocent. Emergent Biosolutions stock is up 47% -- after factoring in today's drop -- in the last year alone. So this may just be a large shareholder taking some gains before the end of the year.

Now what

Unfortunately, this appears to be a simple case of "sometimes stocks go down for no good reason." There's no reason to alter your long-term investment thesis about a company for a single-day movement that isn't supported by actionable news. 

Maxx Chatsko has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Emergent BioSolutions. The Motley Fool has a disclosure policy.