X0508 4 2025-10-10 0001022671 STEEL DYNAMICS INC STLD 0001195950 TEETS RICHARD P JR 7575 W. JEFFERSON BLVD. FORT WAYNE IN 46804 1 0 0 0 0 Common Stock 2025-10-10 4 A 0 12 0 A 4979635 D Common Stock 93119 I By spouse Common Stock 73000 I By Teets Family Foundation Represents the number of shares of common stock underlying additional deferred stock units (DSUs) issued to the reporting person as a dividend equivalent, in connection with this person's retainer as a director under the Company's 2023 Equity Incentive Plan (the "Plan"). This transaction is exempt from both the reporting requirements of Section 16(a), including Rule 16a-11, and the provisions of Section 16(b), by virtue of this dividend reinvestment feature of the Plan and the Company's existing Dividend Reinvestment Plan, as well as being exempt from Section 16(b) independently by virtue of Rule 16b-3(d)(1) and (3). Reportable as directly owned shares of common stock, rather than as a derivative security in Table II, because any and all underlying DSUs are payable, at such time as they are to be settled, solely in shares of common stock. (See Lincoln National Corp. (March 20, 1992) Q.3). Includes shares resulting from reinvestment of dividends on any underlying DSUs included in this total. Represents securities held by the Teets Family Foundation, a charitable foundation of which the reporting person is a member and director. The reporting person has voting and investment power over all securities owned by the foundation. /s/ Richard P. Teets, Jr. 2025-10-14