Image source: Getty Images.

What: Shares of steel manufacturer ArcelorMittal (NYSE:MT) are down 14% as of 12:30 p.m. EDT as the U.K.'s decision to leave the European has sent reverberations across the entire market.

So what: Why would a global steel manufacturer like ArcelorMittal take it on the chin so much harder than most other steel manufacturers? It all comes down to the market each serves. Unlike other U.S.-listed steel companies that sell a vast majority of their production to the American market, more than half of Arcelor's sales by tonnage go to Europe.

If this Brexit vote were to alter the economic landscape of Europe in ways as drastic as pessimists have said, ArcelorMittal would likely feel the sting much more than its more American- or Asian-centric competitors. If ArcelorMittal were a highly profitable company today, perhaps the market would have been more forgiving, but the company has been posting net income losses for more than four years in a row. The company was just barely starting to turn things around -- it has taken deep cuts to costs and has started to pay down debt -- but a slowdown in Europe could halt that progress pretty quickly. 

That is, of course, all depends on whether the worst happens.

Now what: Before investors go making any rash decisions about whether or not they should take action with ArcelorMittal's stock, let's remember one thing: No one really knows the ultimate ramifications of this vote, and it will likely take years before a post-Brexit framework is finalized.

The more important thing investors should focus on, here, is ArcelorMittal's ability to lower its operating costs and continue to cut its debt load to return to profitability. If any decision on this company doesn't have these factors front and center, then it's nothing more than pure speculative fervor that has sent others headed for the exits today.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.