Western Digital Corporation
MX ˙ BMV ˙ US9581021055
SecurityMX:WDC / Western Digital Corporation
InstitutionCerity Partners LLC
Latest Disclosed Ownership173,004 shares
Latest Disclosed Value $ 46,795,757
Cerity Partners LLC ownership in WDC / Western Digital Corporation

On May 15, 2026 - Cerity Partners LLC filed a 13F-HR form disclosing ownership of 173,004 shares of Western Digital Corporation (MX:WDC) valued at $46,795,757 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 11, 2026 disclosing 180,595 shares of Western Digital Corporation. This represents a change in shares of -4.20% during the quarter.

Cerity Partners LLC has a history of taking positions in derivatives of the underlying security (WDC) in the form of stock options. The firm currently holds call options representing 100 of underlying shares valued at $27,049 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.

MX:WDC / 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 173,004 -7,591 -4.20 46,796 50.41 0.0661
2026-02-11 2025-12-31 13F WESTERN DIGITAL COM 958102105 180,595 25,765 16.64 31,111 67.37 0.0453
2025-10-22 2025-09-30 13F WESTERN DIGITAL COM 958102105 154,830 26,458 20.61 18,589 126.30 0.0301
2025-08-13 2025-06-30 13F WESTERN DIGITAL Stock 958102105 128,372 31,205 32.11 8,215 109.11 0.0146
2025-04-30 2025-03-31 13F WESTERN DIGITAL Stock 958102105 97,167 2,120 2.23 3,928 -37.78 0.0080
2025-02-13 2024-12-31 13F WESTERN DIGITAL Stock 958102105 95,047 -56,514 -37.29 6,314 -39.00 0.0137
2024-11-12 2024-09-30 13F WESTERN DIGITAL Stock 958102105 151,561 79,951 111.65 10,350 90.78 0.0229
2024-08-13 2024-06-30 13F WESTERN DIGITAL COM 958102105 71,610 -138,592 -65.93 5,426 -62.18 0.0143
2024-05-14 2024-03-31 13F WESTERN DIGITAL Stock 958102105 210,202 116,276 123.80 14,344 191.60 0.0379
2024-01-26 2023-12-31 13F WESTERN DIGITAL Stock 958102105 93,926 81,137 634.43 4,919 743.74 0.0162
2023-11-14 2023-09-30 13F WESTERN DIGITAL COM 958102105 12,789 -82,561 -86.59 584 -83.88 0.0028
2023-08-14 2023-06-30 13F WESTERN DIGITAL COM 958102105 95,350 9,325 10.84 3,616 11.85 0.0141
2023-05-11 2023-03-31 13F WESTERN DIGITAL COM 958102105 86,025 86,025 3,234 0.0076
2022-11-10 2022-09-30 13F WESTERN DIGITAL COM 958102105 0 -4,930 -100.00 0 -100.00
2022-08-10 2022-06-30 13F WESTERN DIGITAL COM 958102105 4,930 4,930 221 0.0024
2020-05-14 2020-03-31 13F WESTERN DIGITAL COM 958102105 0 -3,633 -100.00 0 -100.00
2020-02-14 2019-12-31 13F WESTERN DIGITAL COM 958102105 3,633 3,633 231 0.0118
2019-05-14 2019-03-31 13F WESTERN DIGITAL COM 958102105 0 -8,192 -100.00 0 -100.00
2019-02-06 2018-12-31 13F WESTERN DIGITAL COM 958102105 8,192 2,727 49.90 303 -5.31 0.0203
2018-11-15 2018-09-30 13F WESTERN DIGITAL COM 958102105 5,465 611 12.59 320 -14.89 0.0222
2018-08-15 2018-06-30 13F WESTERN DIGITAL COM 958102105 4,854 4,854 376 0.0278
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 COM Call 100 27 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.