What: Shares of U.S. Steel (NYSE:X) slumped more than 13% by 11:30 a.m. EST on Wednesday. Uninspiring earnings, coupled with a weak outlook for 2016, led to today's sell-off.

So what: U.S. Steel reported a net loss of $999 million, or $6.83 per share for the fourth quarter. A bulk of that was because the company reported a tax provision of $606 million on its pre-tax loss of $393 million. That said, the company's underlying operations struggled mightily last quarter.  

The company's flat-rolled segment and tubular segment were hardest hit, reporting negative earnings before interest and taxes of $88 million and $64 million, respectively. The flat-rolled segment was hurt by a decrease in average realized prices, due to what it believes were dumped or subsidized imported products on the domestic market. Meanwhile, the tubular segment's decline was due to continued unfavorable market conditions and inefficiencies resulting from reduced production volumes. The company's European segment, on the other hand, delivered positive earnings before interest and taxes of $6 million, but that was weaker than last quarter due to a decrease in average realized euro-based prices and a surge in imports, which it believes are unfairly traded.

Looking ahead, U.S. Steel doesn't anticipate any improvement in 2016 and instead sees "significant headwinds and uncertainty in many of the markets we serve." This is expected to result in its adjusted EBITDA being near break-even, with the expectation being that the company will see lower results in all of its operating segments compared to 2015.

Now what: Times are tough right now for U.S. Steel, with it facing not just weakening market conditions, but intense pressure from foreign competitors. The company is working to combat these issues by reducing its costs and making investments into new products in order to increase its earnings power. That said, it's really at the mercy of the steel market right now, which, at the moment, doesn't appear to be showing any signs of improvement.