Western Digital 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 1,392 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

• Corporate structure and separation. Western Digital completed the spin-off of its flash memory business on 21 February 2025 (referred to in filings as the 'Separation'), distributing Sandisk Corporation as a standalone listed company (Sandisk trades separately; not covered by this file). Established from the FY2026 10-K (period ended 3 Jul 2026, filed 14 Aug 2026, Western Digital's fiscal year runs to early July so this is the most current SEC filing): as part of the Separation, Western Digital initially retained 28.8 million shares of Sandisk common stock. It monetized this retained interest entirely over the following year: 21.3 million shares used in a June 2025 tax-free debt exchange (reducing the Term Loan A-3 by approximately $800 million), 5.8 million shares used in February 2026 to redeem several series of senior notes, and the remaining 1.7 million shares used in Q4 FY2026 in two equity-for-equity exchanges to retire 4.8 million shares of Western Digital's own common stock. The 10-K states explicitly: 'As of July 3, 2026, we no longer held shares of Sandisk common stock.' This is a sourced finding, not an assumption: Western Digital retains no Sandisk equity stake, hence holdings is empty with respect to Sandisk.
• Flash Ventures and Kioxia. The FY2026 10-K states the Company's prior business ventures with Kioxia Corporation (Flash Partners Ltd., Flash Alliance Ltd., Flash Forward Ltd., referred to as 'Flash Ventures') and with Unisplendour Corporation Limited / Unissoft (Wuxi) Group Co. Ltd. (the 'Unis Venture') 'were distributed to Sandisk in connection with the Separation and are included in discontinued operations.' Flash Ventures therefore went with the flash business to Sandisk, not retained by Western Digital; the small Flash Ventures cash-flow lines still appearing in the FY2026 10-K's cash flow statement (notes receivable issuances/proceeds, one distribution) are wind-down/legacy items tied to arrangements that predate or straddle the Separation, not evidence of an ongoing Western Digital equity stake in the venture.
• Other strategic/equity-method investments. The FY2026 10-K was searched for 'equity method', 'unconsolidated', 'joint venture', 'strategic investment', 'non-marketable', 'noncontrolling interest', 'investment in', and 'investee'. 'Non-marketable' and 'noncontrolling interest' returned no hits. The Company's own accounting policy note ('Equity Investments') states it enters into strategic investments accounted for under the equity method or a measurement alternative, with no individual investee named anywhere in the document; the only remaining dollar figure visible is a combined 'Strategic investments and other, net' cash flow line (an $11 million outflow in FY2026). Per the no-combined-balance rule, this figure is not attributable to any single investee, so the holdings array is left empty by design. Both Sandisk (now zero, per the note above) and the pre-Separation Kioxia/Unis ventures (now Sandisk's, not Western Digital's) were the only named strategic relationships found in this filing.
• 958102AT2 note CUSIP. Every 13F-HR checked for this register that reported a Western Digital position also reported holdings on CUSIP 958102AT2 (a 3.000% convertible note maturing 11/1, i.e. a debt instrument), a separate CUSIP from the common stock CUSIP 958102105 despite sharing the six-character issuer prefix: BlackRock (14,465,000 units), FMR (14,696,000 units across 4 lines), State Street (18,950,000 units), Capital Group/Capital World Investors (490,000 units), JPMorgan (7,237,000 units across 2 lines, plus two separate option CUSIPs 958102905 and 958102955), Morgan Stanley (1,001,000 units), and Bank of America (45,000 units). All were excluded from every shares/value total in this file per the derivatives rule; none contributed to any register row's share count. This matches the CUSIP warning in the task brief and the Seagate HDD Cayman note precedent.
• Shares outstanding. The FY2026 10-K cover page states 360,540,944 shares of common stock outstanding as of the close of business on 7 Aug 2026 (the most recent SEC filing, since the 10-Q period-end balance sheet figures are all earlier). The FY2026 10-K's own balance sheet notes state 364 million shares issued and 361 million shares outstanding (rounded) as of 3 Jul 2026, consistent with but less precise than the cover-page figure used here. This is used as shares_outstanding and as the pct_of_company denominator for all Q2 2026 13F register rows, which are as of 30 Jun 2026, roughly 5 weeks earlier than the 7 Aug 2026 share count; the gap is treated as immaterial relative to the size of the register positions. Market cap ($193.25bn) and price ($536.01) are stockanalysis.com's closing figures for 17 Aug 2026, at close 4:00pm EDT; cross-check, 360,540,944 x $536.01 implies approximately $193.25bn, consistent with the reported market cap. Note the share price fell from an implied ~$638.70 at the 30 Jun 2026 13F valuation date to $536.01 by 17 Aug 2026 (about 16% lower); this is a real market move over the intervening seven weeks, not a data error, and explains why 13F dollar values in this register look large relative to the current market cap.
• Register: the Vanguard rule. Vanguard Group Inc (CIK 0000102909) filed Form 13F-NT (notice, no holdings) for the quarter ended 30 June 2026 (filed 13 Aug 2026), confirmed directly against EDGAR's filing-type feed for that CIK. Its Western Digital position is instead reported by two successor entities, Vanguard Capital Management LLC and Vanguard Portfolio Management LLC, summed into the single Vanguard row per project rule 7.
• Register: Capital Group and T. Rowe Price entities. All three Capital Group-family 13F filers in the verified CIK list were checked individually for Q2 2026 and all three hold Western Digital: Capital World Investors (CIK 0001422849, 16,598,211 shares), Capital International Investors (CIK 0001562230, 1,803,588 shares), Capital Research Global Investors (CIK 0001422848, 2,816,570 shares), summed to 21,218,369 shares as one 'Capital Group' row naming all three entities. This is a manager-family roll-up of co-equal sibling filers, not the Vanguard successor case, so is_aggregate is not set. Of the two T. Rowe Price registrants, only T. Rowe Price Associates, Inc. (CIK 0000080255) holds Western Digital (2,075,801 shares, value in thousands, rescaled, see that row's method_note); T. Rowe Price Investment Management, Inc. (CIK 0001897612) was checked directly and holds none.
• Register: stale proxy 13G figures versus fresh 13F. The October 2025 proxy's 5%-holder table (beneficial ownership as of 8 Sep 2025) cites Schedule 13G/13G-A figures for Vanguard (38,579,938 shares, per a 13 Feb 2024 filing, as of 29 Dec 2023), FMR (33,239,191 shares, per an unspecified schedule), BlackRock (27,712,800 shares, per a 25 Jan 2024 13G/A, as of 31 Dec 2023), Managed Account Advisors LLC (22,178,966 shares, not separately verified for this register) and JPMorgan (18,496,725 shares). EDGAR's own SC 13D/13G filing feed for CIK 0000106040 shows no Schedule 13G, 13G/A, 13D or 13D/A filed since 14 Nov 2024, so these proxy-cited figures are 18 to 20+ months stale relative to today. The register above uses each manager's own fresher Q2 2026 Form 13F-HR (or successor sum, for Vanguard) instead; note the resulting numbers differ substantially from the proxy table (e.g. Vanguard 35.6 million now versus 38.6 million per the stale 13G, FMR 26.0 million now versus 33.2 million, BlackRock 33.0 million now versus 27.7 million, JPMorgan 17.0 million now versus 18.5 million), reflecting both the passage of time and the more comprehensive successor-summing and derivative-exclusion methodology used here versus the proxy's single-filer 13G citations.
• No 13D/13G activist or strategic holder. EDGAR's SC 13D/13G filing feed for CIK 0000106040 (Western Digital) shows no Schedule 13D, 13D/A, 13G or 13G/A filed since 14 Nov 2024 (two 13G/A amendments dated then), and none in 2025 or 2026 to date. No activist or newly disclosed strategic 5%+ holder was found beyond the institutional managers in the Q2 2026 13F register above.
• Insider ownership. The most recent DEF 14A on file is dated 6 Oct 2025 (as-of date for the beneficial ownership table: 8 Sep 2025); Western Digital's FY2026 proxy (for the fiscal year ended 3 Jul 2026) had not yet been filed as of 17 Aug 2026. CEO Irving Tan (in the role since Feb 2025, following the Separation, when former CEO David V. Goeckeler became CEO of Sandisk) holds 292,066 shares (0.08% of the proxy's then-outstanding share count of 344,080,824); all 13 current directors and executive officers as a group hold 613,937 shares (0.18%). The proxy discloses a single class of common stock; no dual-class or founder-control structure.
• Self-gate check: summing the twelve non-insider register rows (Vanguard combined, BlackRock, FMR, Capital Group combined, JPMorgan, State Street, Geode, Morgan Stanley, Bank of America, Norges Bank, Northern Trust, T. Rowe Price Associates) plus the Tan row at full value plus the insider group row reduced by Tan's rolled-up shares gives 14 register rows, 183,092,057 shares against 360,540,944 shares outstanding, or 50.78%. This is above the 25 to 45% expected band but within the 15 to 55% outer bound; it is attributable to Western Digital's institutional ownership being unusually concentrated in its largest few holders (Vanguard, BlackRock, FMR and Capital Group alone sum to 115,775,912 shares, 32.11% of shares outstanding) rather than to a double-counted holder or mixed instrument basis; every register row was individually checked against a single common-stock CUSIP (958102105) with derivative CUSIPs excluded, and the implied price per share across all twelve institutional rows clusters tightly at approximately $638.70 (T. Rowe Price row rescaled to match), so no mixed-basis or duplication error was found.