(U.S. Steel earnings story updated with further detail from the company's second-quarter report.)PITTSBURGH ( TheStreet) -- U.S. Steel ( X) startled Wall Street by posting a second-quarter loss Tuesday and by suggesting that its results may deteriorate further in the third period. Analysts had expected the big industrial icon to turn the corner into profitability after a string of red ink stretching back to the start of the recession. Investors sent shares of U.S. Steel down sharply Tuesday morning. In recent trades, the stock was moving at $45.71, down 6.5%, on heavy volume. Before the opening bell, the company reported a net loss in the second quarter of $25 million, or 17 cents a share. The bottom-line numbers included a loss of $96 million, or 62 cents a share, that U.S. Steel blamed on the weakening of the euro against the dollar during the quarter, which hit an intercompany loan U.S. Steel made to one of its European units. Subtracting the loss, the company would have earned 45 cents a share -- still worse than the 63-cent per share profit that analysts, on average, were expecting, according to a survey of the sell side by Thompson Reuters. A year ago, U.S. Steel lost $392 million, or $2.92 a share. It wasn't all bad news. U.S. Steel's second-quarter revenue came to $4.68 billion, more than double the top line it recorded a year ago -- $2.13 billion -- and beating the consensus top-line estimate of $4.63 billion.