UPDATE 3-Steelmaker Nucor's second-quarter profit falls

* Q2 adj profit 46c/shr vs Wall St view 48c/shr

* Company forecasts "modest" Q3 earnings reduction

* Stock down 2 percent in NYSE trading

July 19 (Reuters) - Nucor Corp said its second-quarter profit dropped by almost two-thirds and the steelmaker forecast a "modest" reduction in third-quarter earnings as a surge in foreign imports has pressured already weak steel prices.

The results missed Wall Street expectations and the company's stock fell 2 percent to $37.91 in morning trading on the New York Stock Exchange.

"Continued slow domestic growth, coupled with continued or worsening global economic uncertainty may both become increasing negative factors," the North Carolina-based company said in a statement on Thursday.

"We currently expect to see a modest reduction in earnings exclusive of one-time charges for the third quarter of 2012," Nucor said without elaborating.

Second-quarter net earnings were $112.3 million, or 35 cents per share, compared with $299.8 million, or 94 cents per share in the same quarter of 2011, the company said. Revenue was flat at $5.1 billion as global steel prices have remained weak.

Adjusted for an impairment charge and one other item, the company earned 46 cents per share, on which basis it missed the analysts' estimate of 48 cents per share, according to Thomson Reuters I/B/E/S.

"The negative factors impacting our steel mills include an import surge across most products that began late in 2011 and continued through the first half of 2012, undercutting seasonal pricing momentum that is normally experienced early in the year," the company said.

In addition, U.S. sheet steel markets have been negatively impacted by new domestic supply that began ramping up production in 2011, "while a combination of political and economic uncertainty is beginning to affect steel buyer confidence for all products."

Nucor said lower pricing for scrap metal -- a key ingredient in its steel-making process -- has reduced the profitability of Nucor's scrap processing business.

The average scrap and scrap substitute cost per ton used in the second quarter was $427, a decrease of 4 percent from the first quarter and 4 percent lower than the second quarter of 2011.

Nucor said the average sales price per ton increased slightly from the first quarter, but was down 6 percent from the second quarter of 2011, the company said. Total shipments to outside customers were 5,925,000 tons in the second quarter, a slight increase from the first quarter and 6 percent higher than the year-ago quarter.

The overall operating rate at Nucor's steel mills in the second quarter was 76 percent, down from 79 percent in the first quarter, but higher than the 71 percent in the year-ago second quarter.