Steel Dynamics, Inc.

The full register, from 13F filings

The Register tab above is hand research: a dozen holders, each traced to the filing it came from. This asks the same question of the whole market for the quarter ended 31-mar-2026, where 923 managers reported a position. Broad where the research is deep, and shallow in the ways a 13F always is.

Built from 13F filings, which report US listed, long, US custodied positions only. A register from this source is a floor rather than a level: a holder's true position can be far larger, as BlackRock's ASML stake shows at 1.28m shares in a 13F against 26.3m in its 13G/A. Holdings held through derivatives, outside US custody, or below a manager's reporting obligation do not appear. Where a holder is marked as a family, its total sums several separate filing entities and describes something no single filing describes; the constituent entities and their share counts are listed so the total can be checked. That roll-up can legitimately exceed the family's own Schedule 13G, because a 13G is filed by one legal entity: Vanguard reports Alphabet through ten advisory entities, and The Vanguard Group Inc itself reported zero after its January 2026 disaggregation.

What a reader needs to know to read these numbers

• Steel Dynamics has bought back a large fraction of its shares: 268,694,947 shares were issued as of 30 Jun 2026 but only 143,610,058 were outstanding (125,084,889 held in treasury), and the more recent 10-Q cover page states 143,328,088 shares outstanding as of 23 Jul 2026, which is the shares_outstanding figure used throughout this file as the register denominator.
• Holdings side: three consolidated, majority-owned joint ventures were found and sized from the same standard applied to Nucor's file (a consolidated or equity-method entity that is not wholly owned is a holding at the company's own percentage): Aluminum Dynamics, LLC at 94.4% (with Unity Aluminum, Inc.), United Steel Supply, LLC at 95% (increased from 90% on 1 Apr 2025), and Mesabi Nugget Delaware, LLC at 86%. All three percentages were cross-confirmed against Exhibit 21 of the FY2025 10-K (which carries an ownership-percentage column) and restated unchanged in the Q2 2026 10-Q (period ended 30 Jun 2026, filed 28 Jul 2026). value_usd is null on all three: the only dollar figures disclosed (redeemable noncontrolling interests of $32.0m for USS and $111.2m for Mesabi Nugget at 30 Jun 2026) are the carrying values of the MINORITY interest SDI does not own, not the value of SDI's own majority stake, so using them to size SDI's holding would be exactly the combined-balance/wrong-entity error this project's brief warns against.
• Two entities were checked and found to have EXITED the holdings side during the lookback window, both confirmed via Exhibit 21 and the Q2 2026 10-Q, and are notes rather than rows: New Process Steel, L.P. (NPS) was a 45% equity-method joint venture until SDI acquired the remaining 55% interest on 1 Dec 2025, becoming 100% owned (a $6.5m remeasurement gain was recognized on the previously held 45% interest); SDI Biocarbon Solutions, LLC was a 75% controlling equity interest as of 31 Dec 2025 (per the FY2025 10-K and Exhibit 21) and SDI's ownership increased to 100% effective 19 Jun 2026 (per the Q2 2026 10-Q).
• Search terms run against the FY2025 10-K and the Q2 2026 10-Q to establish the holdings side: 'equity method', 'unconsolidated', 'noncontrolling interest', 'redeemable noncontrolling interest', 'joint venture', 'nonmarketable'/'non-marketable', 'variable interest entity', 'minority interest', '% interest', '% ownership', 'controlling equity interest', 'equity interest in', 'aluminum dynamics', 'cost method', 'available-for-sale', 'marketable securities', and 'investments in unconsolidated'. No non-marketable equity securities, cost-method investments, or VIE disclosures were found beyond the three consolidated JVs and the two now-wholly-owned former JVs already covered above.
• Register: enumerated which entities to check (Vanguard's 8 filing entities, Capital Group's 3 registrants, T. Rowe Price's 2 registrants) from this project's own data/registers/STLD.json snapshot (dated 31-Mar-2026), used ONLY as an entity list. All share and value figures were then read fresh from each holder's own Q2 2026 (period 30 Jun 2026) 13F-HR information table, per the brief. Vanguard Group Inc's parent CIK (0000102909) filed a 13F-NT (no holdings) for Q2 2026, so its 8 successor entities were summed as the family total, matching the documented Vanguard rule. Capital World Investors and Capital International Investors, and T. Rowe Price Investment Management, Inc., were each individually checked and found to hold zero STLD shares in their own Q2 2026 13F-HR filings, so they are recorded here rather than added as null rows.
• The company's 2026 proxy statement's own 'Security Ownership of Certain Beneficial Owners' table lists only two >5% holders (Vanguard and BlackRock), each sourced to a stale Schedule 13G/A (Vanguard: 13 Feb 2024, as of 29 Dec 2023; BlackRock: 5 Feb 2025, as of 31 Dec 2024). Per the brief's guidance to prefer the fresh Q2 2026 13F over a stale 13G quoted in a proxy, this file uses the fresh 13F figures for both (Vanguard 17,084,225 sh vs the proxy's 19,980,395 sh; BlackRock 12,396,499 sh vs the proxy's 11,907,020 sh), and records the proxy figures in each row's own method_note for reconciliation. On the fresh Q2 2026 13F data, State Street (5.15%) and FMR/Fidelity (5.39%) also individually exceed 5%, even though neither appears in the proxy's stale >5% table.
• Self-gate, computed from this file exactly as specified: 13 register rows, chart-summed total 70,255,147 shares (raw sum of all 10 institutional rows plus Millett and Teets, each counted at full value as non-aggregate members, plus the Directors and Executive Officers aggregate row reduced to its residual of 1,384,994 shares because Millett and Teets are both present as members rolling up into it) against shares_outstanding of 143,328,088 = 49.02%. This sits above the '25% to 45% typical' range the brief describes but within the 15% to 55% band it flags as acceptable; the concentration is a genuine consequence of Steel Dynamics' large buyback program (268.7 million shares issued vs 143.3 million outstanding, roughly 47% of issued shares now in treasury), which shrinks the float that the same absolute institutional and insider share counts are measured against, rather than any double-counted or mixed-basis holder.