Nucor Corp, the No.1 U.S. steelmaker, cut its profit forecast for the first quarter, saying higher imports were hurting steel prices.
Nucor expects imports to slow down in the second quarter, but remain at "excessively high levels", the company said on Thursday.
The company's shares fell as much as 6 percent in morning trading.
A stronger dollar has made imports cheaper and steel from China, the biggest producer of the metal, has been flooding the U.S. market in the past few quarters, hurting prices.
Several U.S. steelmakers have cut inventory and costs to cope with the fall in prices.
U.S. Steel Corp temporarily idled its ore operations in Minnesota this month, citing "challenging" market conditions.
Nucor estimated earnings of 10-15 cents per share for the first quarter ending April 4.
The company had earlier said it expected profit to be above 35 cents per share earned a year earlier.
Analyst on average had expected a profit of 40 cents per share, according to Thomson Reuters I/B/E/S.
Nucor's shares were down 4.8 percent at $46.88 in morning trading on the New York Stock Exchange.
Up to Wednesday's close, the stock had fallen about 1 percent in the past 52 weeks, while the U.S. Dow Jones U.S. Iron & Steel index had fallen 14 percent.