Exhibit 99.1

Steel Dynamics Reports Fourth Quarter 2012 Diluted Earnings Per Share of $0.27

FORT WAYNE, INDIANA, January 28, 2013 / PRNewswire / Steel Dynamics, Inc. (NASDAQ/GS: STLD) today announced fourth quarter 2012 net income of $61 million, or $0.27 per diluted share, on net sales of $1.7 billion.  By comparison, prior year fourth quarter net income was $30 million, or $0.14 per diluted share, on net sales of $1.9 billion, and sequential third quarter 2012 net income was $13 million, or $0.06 per diluted share, on net sales of $1.7 billion.   Full-year 2012 net income was $164 million, or $0.73 per diluted share, on net sales of $7.3 billion, compared to prior year net income of $278 million, or $1.22 per diluted share, on net sales of $8.0 billion.

Fourth quarter 2012 results included certain positive tax adjustments of $16 million, or $0.07 per diluted share, which was slightly higher than the company’s previous estimate for the adjustments of $0.06 per diluted share.  Excluding these adjustments the company’s fourth quarter effective tax rate was 39.5 percent.

“Similar to the rest of 2012, the fourth quarter was challenging on a number of fronts,” said President and Chief Executive Officer, Mark Millett, “but the team did a great job.   We are pleased our fourth quarter financial performance was stronger than originally anticipated.  On a sequential quarterly basis our operating income increased 31 percent to $95 million, primarily driven by improvements in our metals recycling and sheet steel operations.

“In our December guidance, we suggested that metals recycling was expected to deliver a stronger financial performance in the fourth quarter, and the team’s execution was even better than anticipated,” stated Millett.  “Sequential quarterly operating income increased 56 percent to $26 million, as meaningful improvements in both ferrous and nonferrous metal spreads more than offset decreased volumes.  Increased copper margins provided the most notable improvement, as global copper prices increased based in part on improved demand from China.  We also took advantage of a strong December ferrous market environment, increasing our expected shipments, as it appeared the typical market strength of January was being challenged.

“Our steel operations also showed improvement with an increase in operating income of seven percent to $117 million, as improvements in sheet steel volumes more than offset weaker long product shipments and lower overall steel metal spreads.  Automotive and manufacturing provided improved sheet demand, while nonresidential construction remained weak.  Despite the challenging construction market, we are also pleased that our fabrication business reported its third consecutive profitable quarter, as the changes the team implemented earlier in the year have continued to provide greater efficiencies and improved productivity.

“The company’s solid performance in a difficult market environment is driven by our ongoing commitment to provide exceptional value to our customers, while taking advantage of our innovative, low-cost operating culture.  We remain committed to leveraging the full complement of our competitive strengths to sustain and grow shareholder value,” Millett concluded.

Fourth Quarter Review

Fourth quarter shipments were mixed across the company’s operating segments when compared to the prior-year fourth quarter and the third quarter of 2012.  However, with the exception of fabrication, pretax earnings improved for each business platform.  The company’s operating income increased 15 percent over prior-year performance and 31 percent in comparison to the third quarter of 2012.   The increase in sequential quarterly operating income was primarily the result of increased volume coupled with reduced

costs in sheet operations, and increased nonferrous margins coupled with reduced direct costs in metals recycling.

The company’s steel mill capacity utilization improved to 80 percent in the fourth quarter from 78 percent in the third quarter, while shipments increased four percent.  Improved overall volume and product mix more than offset decreased steel margins, resulting in increased operating income of $8 million in the quarter.  The average selling price per ton shipped decreased $25 to $784 in the fourth quarter, and the average ferrous scrap cost per ton melted decreased $9 per ton.   Operating income attributable to the company’s sheet operations increased 15 percent when compared to the sequential quarter, while earnings from long product operations decreased three percent.

Despite lower volumes, profitability from the company’s metals recycling operations improved as ferrous metal spreads expanded ten percent and nonferrous metal spreads improved 24 percent when compared to the third quarter of 2012.

The impact of losses from the company’s Minnesota operations on fourth quarter 2012 consolidated net income was approximately $10 million, or $0.04 per diluted share.  This compares to losses of $11 million, or approximately $0.05 per diluted share in the third quarter of 2012.  As previously indicated, a six week outage of the nugget facility began in mid-September 2012 to complete the groundwork necessary for the implementation of improvements expected to be made in the first half of 2013.  These modifications are expected to improve both volume and product quality.  As planned, operations resumed in November, and the restart has gone well with significant improvements to product quality already achieved.

Operations began at the company’s iron concentrate facility in September 2012 and production has gone well.  As the primary raw material for the company’s iron nugget facility, this is a pivotal achievement in lowering the raw material input cost of iron nuggets, as the cost of internally-sourced iron concentrate is less than $50 per metric ton compared to current market priced iron concentrate in excess of $140 per metric ton.  If pig iron prices remain steady, losses associated with the Minnesota operations for the first quarter of 2013 are anticipated to be similar to those recorded in the fourth quarter, as the plant depletes existing higher priced third-party iron concentrate in inventory.

The company’s liquidity position remains strong with $1.5 billion in unrestricted cash, short term commercial paper, and available funding under the revolving credit facility at December 31, 2012.  Total debt decreased $178 million during 2012, and the company’s debt to equity capitalization rate improved from 50 percent at the end of 2011 to 47 percent at December 31, 2012.

Full-Year Review

The company’s 2012 net sales decreased nine percent when compared to 2011, while operating income decreased 33 percent.  Decreased operating income was primarily driven by reduced operating margins in the company’s sheet operations during the first half of 2012, as compared to the record metal spreads achieved in the first half of 2011.  The average annual selling price per ton shipped for the company’s steel operations in 2012 was $831, a decrease of $66 per ton compared to 2011.  The 2012 average scrap cost per ton melted decreased $32.  Operating income from the company’s metals recycling operations also decreased 23 percent during 2012, as both volumes and metal margins compressed.

Charges associated with the company’s 2012 refinancing initiatives resulted in decreased pretax earnings of approximately $38 million, or approximately $0.10 per diluted share.  These initiatives significantly reduced the company’s cost of debt, while extending the company’s long term debt maturity profile.

Outlook

“We remain optimistic that the organic growth projects we identified in 2012 will position us to continue to build a strong enterprise,” Millett said. “We believe there is potential for certain market sectors, such as automotive and manufacturing, to build momentum in 2013.   Recent housing start data suggests potential

improvements in residential construction, and there are areas across the U.S. indicating signs of strengthening in the nonresidential construction sector, although levels remain historically low.  We look forward to executing our strategic growth plans.  Demand for high-quality steel products has not abated, and we believe our current capital projects will deliver products that exceed customers’ expectations.  We remain confident that with our exceptional team, coupled with our superior, low-cost operating culture, we are uniquely prepared to capitalize on the opportunities ahead.”

Summary Fourth Quarter and Full-Year 2012 Operating Segment Information

The following tables highlight operating results for each of the company’s primary operating platforms. References to operating income in the following paragraphs exclude profit-sharing expenses and amortization pertaining to intangible assets.  Dollar amounts are in thousands, excluding per ton data.

Steel Operations

This segment includes five electric-arc-furnace steel mills and related steel finishing and processing facilities, including The Techs. The company’s steel operations produce flat-rolled steel, structural steel, merchant bars, special-bar-quality steel, rebar, rail, and specialty shapes.

Metals Recycling and Ferrous Resources Operations

This segment principally includes the company’s metals recycling operations (OmniSource Corporation), a liquid pig iron production facility (Iron Dynamics), and the company’s Minnesota operations.

Metals Recycling & Ferrous Resources

Metals Recycling

Steel Fabrication Operations

Steel fabrication operations include New Millennium Building Systems, which fabricates steel joists, trusses, and decking used in the construction of non-residential buildings.

About Steel Dynamics, Inc.

Steel Dynamics, Inc. is one of the largest domestic steel producers and metals recyclers in the United States based on estimated annual steelmaking and metals recycling capability, with annual sales of $7.3 billion in 2012, over 6,600 employees, and manufacturing facilities primarily located throughout the United States (including five steel mills, six steel processing facilities, two iron production facilities, over 70 metals recycling locations and six steel fabrication plants).

Forward-Looking Statement

This press release contains some predictive statements about future events, including statements related to conditions in the steel and metallic scrap markets, Steel Dynamics’ revenues, costs of purchased materials, future profitability and earnings, and the operation of new or existing facilities. These statements are intended to be made as “forward-looking,” subject to many risks and uncertainties, within the safe harbor protections of the Private Securities Litigation Reform Act of 1995. These statements speak only as of this date and are based upon information and assumptions, which we consider reasonable as of this date, concerning our businesses and the environments in which they operate. Such predictive statements are not guarantees of future performance, and we undertake no duty to update or revise any such statements. Some factors that could cause such forward-looking statements to turn out differently than anticipated include: (1) the effects of a prolonged or deepening recession on industrial demand; (2) changes in economic conditions, either generally or in any of the steel or scrap-consuming sectors which affect demand for our products, including the strength of the non-residential and residential construction, automotive, appliance, and other steel-consuming industries; (3) fluctuations in the cost of key raw materials (including steel scrap, iron units, and energy costs) and our ability to pass-on any cost increases; (4) the impact of domestic and foreign import price competition; (5) risks and uncertainties involving product and/or technology development; and (6) occurrences of unexpected plant outages or equipment failures.

More specifically, we refer you to SDI’s more detailed explanation of these and other factors and risks that may cause such predictive statements to turn out differently, as set forth in our most recent Annual Report on Form 10-K, in our quarterly reports on Form 10-Q or in other reports which we from time to time file with the Securities and Exchange Commission. These are available publicly on the SEC Web site, www.sec.gov, and on the Steel Dynamics Web site, www.steeldynamics.com.

Conference Call and Webcast

On Tuesday, January 29, 2013, at 9:30 a.m. Eastern Time, Steel Dynamics will host a conference call with investors and analysts to discuss the company’s fourth quarter and full-year 2012 operating and financial results.  We invite you to listen to the live audiocast of the conference call accessible from our website (http://steeldynamics.com) , or via telephone (the conference call number may also be obtained on our website).   A replay of the discussion will be available on our website until midnight on  February 5, 2013.  A podcast of the event will also be available and can be downloaded from our website.

Contact:  Marlene Owen, Director Investor Relations —+1.260.969.3500

Steel Dynamics, Inc.

CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)

(in thousands, except per share data)

Steel Dynamics, Inc.

UNAUDITED SUPPLEMENTAL OPERATING INFORMATION

(dollars in thousands)

*                   Steel Operations include the company’s five steelmaking divisions and The Techs three galvanizing plants.

**              Metals Recycling and Ferrous Resources Operations include OmniSource; Iron Dynamics (all shipments are internal); and Minnesota Operations, including Mesabi Nugget (all shipments have been internal).

***         Steel Fabrication Operations include the company’s joist and deck fabrication operations.

(Note 1) Segment operating income (loss) excludes profit sharing expense.

Steel Dynamics, Inc.

CONSOLIDATED BALANCE SHEETS

(in thousands)

Steel Dynamics, Inc.

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)

(in thousands)