Sandisk Corporation

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 1,158 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

• Separation from Western Digital and whether WDC retained a stake: YES, initially, and it has since been fully sold down to zero. Western Digital completed the spin-off of Sandisk on 21 Feb 2025, distributing approximately 80.1% of the shares it then held to WDC stockholders and initially retaining the remaining approximately 19.9% (28,827,787 shares) for itself. This is confirmed directly in this task by two Schedule 13G filings made BY Western Digital Corporation (CIK 0000106040) ON Sandisk (CIK 0002023554): a Schedule 13G filed 3 Apr 2025 (event date 31 Mar 2025) reporting 28,827,787 shares, 19.9% of class; and a Schedule 13G/A filed 1 Jul 2025 (event date 30 Jun 2025) reporting the position reduced to 7,513,019 shares, 5.2% of class, after a June 2025 tax-free debt exchange used 21,314,768 of those shares. Sandisk's own 2025 proxy (DEF 14A, as-of 5 Sep 2025) lists Western Digital Corporation as a 5%+ holder at 7,513,019 shares, 5.1%, consistent with the 13G/A. No further 13G/A from Western Digital was filed on Sandisk after 1 Jul 2025, which is consistent with Western Digital's own FY2026 10-K (already in this database, western-digital.json) stating that a Feb 2026 note redemption (5.8 million shares) and two Q4 FY2026 equity-for-equity exchanges (1.7 million shares) retired the remainder, and that 'As of July 3, 2026, we no longer held shares of Sandisk common stock.' CONCLUSION: this is NOT a gap in western-digital.json. That file already documents the full retain-then-sell-to-zero history accurately in its notes, with sources; this task's independent check via Sandisk's own 13G filings corroborates it exactly (same 28,827,787-share and 7,513,019-share figures). Because Western Digital holds zero Sandisk shares as of the most current information, it does not appear as a register row here; the history is recorded in this note instead, per the task's zero-tracking instruction.
• Fiscal periods used. Sandisk's fiscal year ends in late June/early July (it kept WDC's calendar): FY2026 ended 3 Jul 2026. The FY2026 Form 10-K (filed 17 Aug 2026, the most current SEC filing for the company) is the basis for company.shares_outstanding (146,419,001 shares as of the close of business on 7 Aug 2026, per the 10-K cover page) and for all holdings-side figures (balance sheet and notes as of 3 Jul 2026). No stock split or reclassification was found (a targeted search of the 10-K for 'stock split', 'forward split', 'reverse split' and 'split-adjusted' returned zero hits), and the share count has moved smoothly from 144.9 million at the Feb 2025 separation to 145.3 million (May 2025, per Western Digital's 13G/A) to 146.4 million (Aug 2026), consistent with ordinary equity compensation issuance rather than a split. The register's institutional rows are Q2 2026 (30 Jun 2026) 13F/13G data, the most recent available as of 18 Aug 2026; the insider rows are from the 2025 proxy (DEF 14A, as-of 5 Sep 2025), the only proxy on file, since Sandisk's first FY2026 proxy has not yet been filed.
• Holdings side: six positions, three private manufacturing/sales joint ventures with individually disclosed 49.9% stakes (Flash Partners, Flash Alliance, Flash Forward, the Flash Ventures with Kioxia Corporation), two further private joint ventures with disclosed percentages but no individually disclosed carrying value (the 48%-owned Unis Venture in China, the 20%-owned SDSS assembly/test venture in Shanghai with JCET), and one large public strategic stake (approximately 3.9% of Nanya Technology Corporation, a Taiwan Stock Exchange-listed DRAM maker, acquired via a $970 million private placement in Apr 2026, now fair-valued at $1,777 million). The FY2026 10-K's Note 16 'Summarized Financial Information' discloses a COMBINED total net equity of $1,025 million (2026) across all three non-Flash-Ventures-labelled ventures together (Flash Ventures, Unis Venture and SDSS) on a 100%-of-investee basis; per the no-combined-balance rule this figure is not attributed to Unis Venture or SDSS individually and both are left value_usd null, with the combined figure recorded here and in unknowns.
• Register: the Vanguard rule. Vanguard Group Inc (CIK 0000102909) filed Form 13F-NT (notice, no holdings) for the quarter ended 30 Jun 2026, the same pattern already verified for Western Digital in this database. Its Sandisk position is reported by two successor entities, Vanguard Capital Management LLC and Vanguard Portfolio Management LLC, summed into the single Vanguard row (13,184,192 shares). Five further legacy Vanguard CIKs were checked and found to have no Q2 2026 filing (last filed for Q1 2026, mid-May 2026), consistent with a January 2026 Vanguard filing-entity reorganisation rather than a coverage gap.
• Register: the three brief-flagged concentrated holders (Dodge & Cox, Berkshire Hathaway, Wellington). All three were checked directly against their own Q2 2026 13F-HR filings for Sandisk (CUSIP 80004C200). Dodge & Cox (CIK 0000200217): checked, does not hold Sandisk (a fragment search on 'SAND' matched only an unrelated Las Vegas Sands Corp. position, confirming the filing was actually searched, not merely assumed empty). Berkshire Hathaway Inc (CIK 0001067983): checked, does not hold Sandisk (no match at all on 'SAND'). Wellington Management Group LLP (CIK 0000902219, located via EDGAR full text search after the standard company-name browse-edgar search failed to surface it): DOES hold Sandisk, 1,066,886 shares, 0.73% of the company, included as a register row above. This is a real but smaller position than the brief's own example figures for a different company (9.4%, 8.72%, 4.7% respectively); here only Wellington actually holds a Sandisk position among the three.
• Register: a fourth concentrated/event-driven holder found via Schedule 13G rather than any checklist. Jane Street Group, LLC (a market maker and prop trading firm) filed a Schedule 13G on 5 Aug 2026 (event date 30 Jul 2026) reporting 7,409,437 shares, 5.0% of class, across three subsidiaries. Included as a register row (basis filed_13g). This matches the brief's warning that a recently spun company attracts event-driven and merger-arbitrage managers outside any standard institutional checklist.
• Register: DnB Asset Management AS, a small holder that shrank below register materiality. Sandisk's Oct 2025 proxy cites a 13G/A putting DnB at 7,109,285 shares, 5.8%, but a fresher Schedule 13G/A filed 10 Nov 2025 (event date 30 Sep 2025) shows the position reduced to 1,025,373 shares, 0.7%. Not included as a register row given its current immateriality (well under 1%), but recorded here as a verified decline (both presence and the subsequent reduction were checked, not assumed).
• No Schedule 13D activist holder was found: EDGAR's filing history for CIK 0002023554 shows Schedule 13G and 13G/A filings only, no 13D or 13D/A, so no activist stake is recorded.
• Self-gate check, computed exactly as the register-chart formula specifies: members = {'All Directors and Current Executive Officers as a group (12 persons)': 228,566} from Goeckeler's rolls_up_into. Summing all 15 register rows at full value except the aggregate group row (reduced to its residual of 310,256 - 228,566 = 81,690) gives a total of 61,605,670 shares against 146,419,001 shares outstanding, or 42.07%. This falls within the brief's expected 25 to 45% band despite Sandisk being a company that has existed as a standalone registrant for only about 18 months, which is attributable to unusually fast and heavy institutional accumulation during the fiscal-2026 flash-memory/AI-driven earnings surge (net income $11.4 billion for FY2026, versus a $1.6 billion loss the prior year) rather than to any double-counted holder or mixed-instrument error; every institutional row was checked against the single common-stock CUSIP 80004C200 with derivatives excluded, and implied price per share across the twelve 13F rows (excluding T. Rowe Price, rescaled to match, and Jane Street, whose 13G discloses no dollar value) clusters tightly around $2,273.6, consistent with a single valuation basis.