EXHIBIT 31.2

CERTIFICATION PURSUANT TO SECTION 302 OF THE

SARBANES-OXLEY ACT OF 2002

I, Theresa E. Wagler, certify that:

1.I have reviewed this annual report on Form 10-K/A Amendment No. 1 of Steel Dynamics, Inc.;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

Date:     June 10, 2015
	/s/THERESA E. WAGLER
	Theresa E. Wagler
	Executive Vice President and Chief Financial Officer
	(Principal Financial Officer and Principal Accounting Officer)