Exhibit 99.1

7575 W. Jefferson Blvd.

Fort Wayne, IN  46804

Steel Dynamics Reports Third Quarter 2015 Results

FORT WAYNE, INDIANA, October 19, 2015 / PRNewswire / Steel Dynamics, Inc. (NASDAQ/GS: STLD) today announced third quarter 2015 net income of $61 million, or $0.25 per diluted share, on net sales of $2.0 billion.   Comparatively, prior year third quarter net income was $91 million, or $0.38 per diluted share, on net sales of $2.3 billion, and sequential second quarter 2015 net sales were $2.0 billion, with adjusted net income of $53 million, or $0.22 per diluted share, which excluded expenses of $0.09 per diluted share associated with both idling the company’s Minnesota operations and planned furnace maintenance at Iron Dynamics.

“The third quarter 2015 market environment continued to be challenging for our steel and metals recycling operations,” said Mark D. Millett, Chief Executive Officer. “Ongoing pressure from steel imports remains high, negatively impacting steel pricing and domestic steel production, resulting in industry utilization not fully reflecting the actual strength in U.S. steel consumption.  The automotive market remains strong and construction continues its steady improvement.  However, customer steel inventories remain at elevated levels and when combined with further declining scrap prices, have resulted in hesitant ordering.  As scrap prices stabilize at these lower levels and steel inventories moderate to more normalized quantities into 2016, we believe domestic steel production should improve.

“An important barometer for domestic steel consumption is the strength of the construction industry.  Historically, the construction industry has been the largest single domestic steel consuming sector, and it is continuing on an upward trend,” continued Millett.  “For the second consecutive quarter, our fabrication operations achieved record profitability.  Steady demand resulted in a 17 percent increase in third quarter 2015 fabrication shipments and orders remain robust, reflecting the steady positive trend in the non-residential construction market.  Our fabrication operating profitability has increased $56 million, or 184 percent, so far this year, when compared to 2014.

“Despite the headwind from imports, we achieved a nine percent improvement in third quarter 2015 operating income, as compared to sequential second quarter 2015 adjusted operating income (excluding the idled Minnesota Operations and the Iron Dynamics outage impact), based on record fabrication performance and a 25 percent improvement in our steel segment profitability,” concluded Millett.

The company generated cash flow from operations of $164 million during the third quarter 2015.  With available cash of $474 million at September 30, 2015, the company achieved record liquidity of $1.7 billion, providing a firm foundation for growth.  During the nine months ended September 30, 2015, the company generated $708 million of cash flow from operations, and after considering capital expenditures, generated $622 million of free cash flow.

Additional Third Quarter 2015 Comments

While steel imports continued to flood the domestic market, U.S. steel consumption remained steady resulting in relatively flat steel and metals recycling shipments.  Third quarter 2015 operating income for the company’s steel operations increased 25 percent to $127 million, due to metal spread expansion, as both average steel product pricing and raw material scrap costs improved in the quarter.  The average product selling price for the company’s steel operations increased $3 to $665 per ton.  The average ferrous scrap cost per ton melted decreased $3 to $252 per ton.

Third quarter 2015 operating income attributable to the company’s sheet products increased six percent when compared to the sequential second quarter.  Although the company’s flat roll shipments decreased four percent, the improvement in metal spread more than offset the negative impact of reduced volume.  Flat roll products, specifically commodity-grade hot roll, were the most severely impacted by high import volumes.  Operating income from long products increased 21 percent, based on improved engineered special-bar-quality shipments and other sequential quarterly cost improvements in the group.  Driven by weaker flat roll volume, the company’s steel production

utilization rate declined to 82 percent for the third quarter 2015, which remains higher than the average U.S. domestic steel mill utilization rate, but lower than the company’s second quarter 2015 rate of 87 percent.

The company’s metals recycling operations recorded third quarter 2015 operating income of $463,000, compared to second quarter 2015 operating income of $12 million.  Sequential quarterly ferrous pricing was down three percent and procurement costs rose, resulting in a 14 percent reduction in metal margin.  Additionally, non-ferrous market indices fell over ten percent in the third quarter 2015, resulting in a 20 percent reduction in metal margin.

The company’s fabrication operations continued to achieve record financial performance. Third quarter 2015 operating income of $37 million surpassed the sequential second quarter’s previous record by 33 percent.  Sustained strong demand combined with lower raw material steel costs, supported metal spread expansion.

Year-to-Date Comparison

For the nine months ended September 30, 2015, net income was $123 million, or $0.51 per diluted share, on net sales of $6.0 billion, as compared to net income of $202 million, or $0.85 per diluted share, on net sales of $6.2 billion for the nine months ended September 30, 2014.  Year-to-date consolidated net sales decreased four percent, as a result of a $539 million, or 32 percent, reduction in metals recycling revenue related to decreased demand, which resulted in meaningful reduction in both 2015 shipments and pricing.   Year-to-date consolidated operating income decreased $93 million, or 23 percent, primarily as the result of decreased earnings from the company’s steel operations.  Excluding the second quarter 2015 impact from idling the Minnesota iron production facilities and the Iron Dynamics maintenance outage, year-to-date adjusted operating income declined 16 percent, to $351 million.  The average year-to-date selling price for the company’s steel operations decreased $142 to $694 per ton.  The average year-to-date ferrous scrap cost per ton melted decreased $95 to $271 per ton.

Outlook

“We believe the current elevated level of domestic supply chain inventory, combined with the continuation of excessive steel imports and typical fourth quarter seasonality, could further erode domestic steel industry profitability in the fourth quarter 2015,” said Millett.  “While underlying steel demand in certain market sectors remains steady and import levels have somewhat declined, the issue of steel imports persists.  Nonetheless, we continue to strengthen our financial position through strong cash flow generation, record liquidity, and the execution of our long-term strategy.  We are well-positioned for additional growth.  The recently announced purchase of steel decking facilities is an example of an investment that provides an excellent financial return and further diversifies our product capabilities within our fabrication group.  Customer focus, coupled with our market diversification and low-cost operating platforms, support our ability to not only maintain our best-in-class industry performance, but to also grow in a challenging environment,” concluded Millett.

Supplemental Quarterly Information — New Segment Presentation (1)

(1)  Effective the third quarter 2015, our reporting segments are Steel, which includes our steel mills and finishing facilities as well as Iron Dynamics; Metals    recycling, which consists solely of OmniSource: and Fabrication, which consists solely of New Millennium Building Systems. Minnesota operations is reflected in non-segment operations. All prior periods have been restated consistent with this new segment presentation.

(2)     Amount excludes 2Q 2015 expenses associated with the idled Minnesota Operations (amount includes non-controlling interests of approximately $4 million), the impact from the Q2 2015 Iron Dynamics planned furnace maintenance outage that generally is required once every 5 years, and the Q3 2014 impact of purchase accounting related to the Severstal Columbus acquisition.

Conference Call and Webcast

Steel Dynamics, Inc. will hold a conference call to discuss third quarter 2015 operating and financial results on Tuesday, October 20, 2015, at 10:00 a.m. Eastern Time.  You may access the call and find dial-in information on the Investor Relations section of the company’s website at www.steeldynamics.com.  A replay of the call will be available on our website until 11:59 p.m. Eastern Time on October 25, 2015.

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 $8.8 billion in 2014, approximately 7,600 employees, and manufacturing facilities primarily located throughout the United States (including six steel mills, eight steel coating facilities, an iron production facility, approximately 80 metals recycling locations and eight steel fabrication plants).

Note Regarding Non-GAAP Financial Measures

The company reports its financial results in accordance with U.S. generally accepted accounting principles (GAAP). Management believes that EBITDA and Adjusted EBITDA, non-GAAP financial measures, provide additional meaningful information regarding the company’s performance and financial strength. Non-GAAP financial measures should be viewed in addition to, and not as an alternative for, the company’s reported results prepared in accordance with GAAP. In addition, because not all companies use identical calculations, EBITDA included in this release may not be comparable to similarly titled measures of other companies.

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 uncertain economic conditions; (2) cyclical and changing industrial demand; (3) changes in conditions in any of the steel or scrap-consuming sectors of the economy which affect demand for our products, including the strength of the non-residential and residential construction, automotive, appliance, pipe and tube, and other steel-consuming industries; (4) 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; (5) the impact of domestic and foreign import price competition; (6) unanticipated difficulties in integrating or starting up new or acquired businesses; (7) risks and uncertainties involving product and/or technology development; and (8) 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 website, www.sec.gov, and on the Steel Dynamics website, www.steeldynamics.com.

Contact:  Marlene Owen, Director Investor Relations —+1.260.969.3500

Steel Dynamics, Inc.

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Steel Dynamics, Inc.

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