Exhibit 99.1

Steel Dynamics Reports Second Quarter 2013 Diluted Earnings Per Share of $0.13

FORT WAYNE, INDIANA, July 17, 2013 / PRNewswire / Steel Dynamics, Inc. (NASDAQ/GS: STLD) today announced second quarter 2013 net income of $29 million, or $0.13 per diluted share, on net sales of $1.8 billion.  By comparison, prior year second quarter net income was $44 million, or $0.20 per diluted share, on net sales of $1.9 billion; and sequential first quarter 2013 net income was $48 million, or $0.21 per diluted share, on net sales of $1.8 billion.

“Specific to product pricing, the second quarter proved most challenging for our sheet and structural steel operations,” said President and Chief Executive Officer, Mark Millett. “Slower anticipated economic growth in China coupled with suppressed economic growth in the European community influenced near-term market sentiment.  The persistent uncertainty in the domestic economic environment continued to influence customer buying patterns as they maintained low inventory levels.  Domestic oversupply, coupled with increased quarter-over-quarter steel imports, resulted in decreased quarterly selling values.

“Compared to the first quarter, operating income from our steel operations decreased 28 percent to $88 million, driven by metal margin compression caused by declines in average consecutive quarterly sheet and structural steel pricing, which more than offset the benefit of increased overall volume,” stated Millett.  “We saw meaningful volume improvements for rail, engineered special bar quality products, and galvanized sheet steel from The Techs.  Modest growth in the overall construction market continued in the quarter and supported improved shipments and backlog for our fabrication business, which achieved its fifth consecutive profitable quarter.

“We noted in our second quarter guidance that we were anticipating potential challenges in the metals recycling market.  Operating income from our metals recycling operations decreased 37% to $16 million, when compared to first quarter.  While ferrous volumes and metal spreads remained somewhat flat, nonferrous volume and margins contracted meaningfully in the quarter, as both copper and stainless steel market prices decreased significantly,” said Millett.

Second Quarter Review

Second quarter shipments improved in the company’s steel and fabrication operating segments when compared to the first quarter, but were lower for both metals recycling and ferrous operations.  Operating income for the company’s steel operations decreased as compared to the sequential first quarter, declining 28 percent, and declined 37 percent as compared to the second quarter 2012, primarily due to lower steel metal spreads, as declining steel prices more than offset increased volume.

The company’s steel mill production utilization rate was 83 percent in the second quarter, compared to 89 percent in the first quarter of 2013.  Planned maintenance downtime in April at the Flat Roll and Engineered Bar divisions was the primary reason for the decrease.  The Structural and Rail Division continued a positive utilization trend as standard rail volume increased 20 percent over the sequential quarter.  The average selling price for the company’s steel operations per ton shipped decreased $8 to $781 in the second quarter, and the average ferrous scrap cost per ton melted increased $3 per ton.  Operating income attributable to the company’s long product operations decreased 20 percent when compared to the sequential quarter, while earnings from sheet operations decreased 34 percent.

Sequential operating income for the metals recycling operations decreased in the second quarter of 2013 to $16 million, as compared to $25 million of operating income in the first quarter, although contribution to the company’s overall operating income was higher than the second quarter 2012 of $5 million.  Nonferrous shipments decreased nine percent sequentially, and when combined with generally lower pricing, the nonferrous metal spread decreased ten percent. The lower nonferrous volume is primarily attributed to a decrease in copper and stainless shipments, as lower pricing adversely impacted flow toward the end of the second quarter.

The impact of losses from the company’s Minnesota operations on second quarter 2013 consolidated net income was approximately $9 million, or $0.04 per diluted share, as compared to a loss of $14 million, or $0.06 per diluted share, in the first quarter. As previously indicated and according to plan, the installation of additional equipment and other modifications were made at the iron nugget facility in April.  The facility resumed production in May and the restart has progressed well.  Production is expected to increase steadily and reach a monthly rate of 30,000 metric tons before the end of the year.  The company anticipates the impact of losses related to the Minnesota operations for the third quarter 2013 to be similar to somewhat improved compared to those recorded in the second quarter as expected yield and production improvements are realized.

Year to Date Comparison

A decline in average steel prices and decreased nonferrous shipments resulted in net sales of $3.6 billion for the six months ended June 30, 2013, an eight percent decline from the same period in 2012. Operating income decreased 26 percent, as margins decreased within the company’s steel operations.  The average selling price per ton shipped for the company’s steel operations in the six months ended June 30, 2013 was $785, a decrease of $79 per ton compared to the same period last year.  The average ferrous scrap cost per ton melted was $54 lower than the comparative period for 2012.

Outlook

“We remain optimistic as the demand for high-quality steel products has not abated,” Millett said. “The team is on track to complete the organic growth projects scheduled to start at the end of this year, including the engineered special-bar-quality capacity expansion and the premium rail product addition.  The automotive market remains strong, and manufactured goods is strengthening.  Housing start data continues to suggest increasingly higher potential for a sustainable recovery in residential construction.  We remain cautiously optimistic about the nonresidential construction market in 2013, as the most recent key market indices showed upward improvements. We also view the increase in our engineered special-bar-quality products and fabrication shipments as positive signs of momentum.  We are confident that with our exceptional team, and our superior, low-cost operating culture, we are uniquely prepared to capitalize on the opportunities ahead.”

Summary Second Quarter 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, engineered 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 iron producing 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 recurrent slowing economy 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 Thursday, July 18, 2013, at 10:00 a.m. Eastern Time, Steel Dynamics will host a conference call with investors and analysts to discuss the company’s second quarter 2013 operating and financial results.  We invite you to listen to the live audiocast of the conference call accessible from our website (http://www.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 July 25, 2013.  A downloadable podcast and MP3 file of the event will also be available on 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)

(Note 1)  Excludes the impact of the 5.125% convertible senior notes from net income (numerator) and share equivalents outstanding (denominator) for the three months ended June 30, 2013, as the impact to diluted earnings per share is anti-dilutive.

Steel Dynamics, Inc.

UNAUDITED SUPPLEMENTAL OPERATING INFORMATION

(dollars in thousands)

Steel Dynamics, Inc.

CONSOLIDATED BALANCE SHEETS

(in thousands)

Steel Dynamics, Inc.

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)

(in thousands)