Western Digital Corporation
CH ˙ BRSE ˙ US9581021055
DETTE SYMBOL ER IKKE LÆNGERE AKTIVT
SecurityCH:12355 / Western Digital Corporation
InstitutionAdvisor Group Holdings, Inc.
Latest Disclosed Ownership68,556 shares
Latest Disclosed Value $ 18,545,487
Advisor Group Holdings, Inc. ownership in 12355 / Western Digital Corporation

On May 15, 2026 - Advisor Group Holdings, Inc. filed a 13F-HR form disclosing ownership of 68,556 shares of Western Digital Corporation (CH:12355) valued at $18,545,487 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 86,612 shares of Western Digital Corporation. This represents a change in shares of -20.85% during the quarter.

Advisor Group Holdings, Inc. has a history of taking positions in derivatives of the underlying security (12355) in the form of stock options. The firm currently holds call options representing 1 of underlying shares valued at $18,700 USD .

Note: prior versions of this page mistakenly stated that the share values represented the number of options, not the number of underlying shares. For more information on the data backing these reports, please see the SEC document Frequently Asked Questions About Form 13F.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Institutional Put/Call Ratios
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In addition to reporting standard equity and debt issues, institutions with more than 100MM assets under management must also disclose their put and call option holdings. Since put options generally indicate negative sentiment, and call options indicate positive sentiment, we can get a sense of the overall institutional sentiment by plotting the ratio of puts to calls. The chart to the right plots the historical put/call ratio for this instrument.

Using Put/Call Ratio as an indicator of investor sentiment overcomes one of the key deficiencies of using total institutional ownership, which is that a significant amount of assets under management are invested passively to track indices. Passively-managed funds do not typically buy options, so the put/call ratio indicator more closely tracks the sentiment of actively-managed funds.

CH:12355 / Western Digital Corporation Historical Put/Call Ratio
Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date
Effective
Date
Form Security Class ID Avg Price
Paid (Est)
Reported
Shares
ΔShares ΔShares
(%)
Reported
Value
(x1000)
ΔValue
(%)
Alloc
(%)
ΔAlloc ΔAlloc (%) Cost Basis
(x1000)
Unrealized
Gain/Loss
(x1000)
2026-05-15 2026-03-31 13F WESTERN DIGITAL COM 958102105 68,556 -18,056 -20.85 18,545 24.29 0.0158
2026-02-17 2025-12-31 13F WESTERN DIGITAL COM 958102105 86,612 21,573 33.17 14,922 120.24 0.0218
2025-11-14 2025-09-30 13F WESTERN DIGITAL COM 958102105 65,039 42,579 189.58 6,775 410.94 0.0095
2025-09-04 2025-06-30 13F/A-1 ESTERN DIGITAL COM 958102105 22,460 4,719 26.60 1,326 84.94 0.0024
2025-08-13 2025-06-30 13F ESTERN DIGITAL COM 958102105 14,808 -2,933 802 0.0009
2025-05-12 2025-03-31 13F WESTERN DIGITAL COM 958102105 17,741 3,691 26.27 717 -14.34 0.0016
2025-06-06 2024-12-31 13F/A-1 WESTERN DIGITAL COM 958102105 14,050 -44,594 -76.04 838 -79.10 0.0019
2025-02-07 2024-12-31 13F WESTERN DIGITAL COM 958102105 52,753 -5,891 3,549 0.0091
2024-11-13 2024-09-30 13F WESTERN DIGITAL COM 958102105 58,644 -10,299 -14.94 4,005 -23.34 0.0090
2024-08-13 2024-06-30 13F WESTERN DIGITAL COM 958102105 68,943 -5,513 -7.40 5,224 2.81 0.0123
2024-05-10 2024-03-31 13F WESTERN DIGITAL COM 958102105 74,456 46,453 165.89 5,081 246.52 0.0113
2024-02-12 2023-12-31 13F WESTERN DIGITAL COM 958102105 28,003 675 2.47 1,466 17.66 0.0026
2023-11-13 2023-09-30 13F WESTERN DIGITAL COM 958102105 27,328 -1,353 -4.72 1,247 14.63 0.0018
2023-08-21 2023-06-30 13F/A-1 WESTERN DIGITAL COM 958102105 28,681 -1,007 -3.39 1,088 -2.77 0.0020
2023-08-10 2023-06-30 13F WESTERN DIGITAL COM 958102105 30,232 544 1,086 0.0003
2023-05-12 2023-03-31 13F WESTERN DIGITAL COM 958102105 29,688 -4,413 -12.94 1,119 4.10 0.0021
2023-02-10 2022-12-31 13F WESTERN DIGITAL COM 958102105 34,101 -6,961 -16.95 1,075 -19.61 0.0022
2022-11-14 2022-09-30 13F WESTERN DIGITAL COM 958102105 41,062 734 1.82 1,336 -26.02 0.0031
2022-08-10 2022-06-30 13F WESTERN DIGITAL COM 958102105 40,328 2,204 5.78 1,806 -38.19 0.0040
2022-05-04 2022-03-31 13F WESTERN DIGITAL COM 958102105 38,124 -3,399 -8.19 2,922 7.82 0.0057
2022-02-03 2021-12-31 13F WESTERN DIGITAL COM 958102105 41,523 11,792 39.66 2,710 61.50 0.0051
2021-11-05 2021-09-30 13F WESTERN DIGITAL COM 958102105 29,731 -1,646 -5.25 1,678 -24.85 0.0035
2021-08-02 2021-06-30 13F WESTERN DIGITAL COM 958102105 31,377 5,108 19.44 2,233 26.95 0.0048
2021-05-13 2021-03-31 13F WESTERN DIGITAL COM 958102105 26,269 -544 -2.03 1,759 18.45 0.0042
2021-02-10 2020-12-31 13F WESTERN DIGITAL COM 958102105 26,813 -5,686 -17.50 1,485 25.11 0.0040
2020-11-12 2020-09-30 13F WESTERN DIGITAL COM 958102105 32,499 7,517 30.09 1,187 7.62 0.0036
2020-08-14 2020-06-30 13F WESTERN DIGITAL COM 958102105 24,982 -5,141 -17.07 1,103 -7.62 0.0037
2020-05-18 2020-03-31 13F WESTERN DIGITAL COM 958102105 30,123 30,123 1,194 0.0049
Disclosed Call Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share
Price
Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-15 2026-03-31 13F WESTERN DIGITAL CALL Call 1 0.00 19 100.00 n/a n/a n/a
2026-02-17 2025-12-31 13F WESTERN DIGITAL CALL Call 1 9 n/a n/a n/a
2021-02-10 2020-12-31 13F WESTERN DIGITAL CALL COM Call 0 -100.00 0 n/a n/a n/a
2020-11-12 2020-09-30 13F WESTERN DIGITAL CALL COM Call 5 0.00 0 -100.00 n/a n/a n/a
2020-08-14 2020-06-30 13F WESTERN DIGITAL CALL COM Call 5 2 n/a n/a n/a
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.