The chief executive of mining and resources company Cleveland-Cliffs Inc. CLF, +2.97% slammed a Goldman Sachs analyst on the company's earnings call earlier Friday, accusing him of failing to understand numbers. "You don't understand your own business. You are a disaster. You are an embarrassment to your parents," Lourenco Goncalves said in response to a question from another analyst on the call, according to a FactSet transcript. He later challenged Goldman Sachs analyst Matthew Korn to ask a question, after the operator said Korn was not on the call. He finished the conference call with a direct message for Korn. "Matthew Korn from Goldman Sachs, you can run, but you can't hide. I will see you at the Goldman Sachs Conference, very soon and bring your commodity that guy because you owe me that for the last year. It will be easier for you if you have the commodity that guy with you interviewing me. If you are alone, it would be a lot worse, it will be bad no matter what, but it will be a lot worse if you're alone," Goncalves said. Cleveland-Cliffs shares fell 5.6% on Friday but are up 50% in 2018, while the S&P 500 SPX, +1.59% has gained about 4%.