Shares of United States Steel Corp. slid about 10% Friday, after the company’s first-quarter earnings released late Thursday fell short of expectations and the company warned of potential “operational volatility.” The company said it is going through “operational challenges” at its steelmaking plant at Great Lakes Works in Michigan, which hit its bottom line by about $30 million in the second quarter. Cowen analysts said the company’s EBITDA guidance was below consensus, even excluding the Great Lakes charge. Cowen rates the stock market perform. U.S. Steel is holding a conference call this morning. Shares are down 3% in the year so far, while the S&P 500 has fallen 0.2%.