Western Digital Corporation
AT ˙ WBAG ˙ US9581021055
468,45 € ↓ -49,35 (-9,53%)
2026-06-05
DEL PRIS
SecurityAT:WDC / Western Digital Corporation
InstitutionAsset Management One Co., Ltd.
Latest Disclosed Ownership148,345 shares
Latest Disclosed Value $ 40,125,839
Asset Management One Co., Ltd. reports 2.96% decrease in ownership of WDC / Western Digital Corporation

On May 8, 2026 - Asset Management One Co., Ltd. filed a 13F-HR form disclosing ownership of 148,345 shares of Western Digital Corporation (AT:WDC) valued at $33,385,042 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 27, 2026 disclosing 152,876 shares of Western Digital Corporation. This represents a change in shares of -2.96% during the quarter. The current value of the position is $69,492,215 USD.

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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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)
2026-05-08 2026-03-31 13F WESTERN DIGITAL COM 958102105 148,345 -4,531 -2.96 40,126 46.18 0.1183
2026-01-27 2025-12-31 13F WESTERN DIGITAL COM 958102105 152,876 2,024 1.34 27,449 51.56 0.0763
2025-10-22 2025-09-30 13F WESTERN DIGITAL COM 958102105 150,852 3,089 2.09 18,111 91.55 0.0525
2025-07-31 2025-06-30 13F WESTERN DIGITAL COM 958102105 147,763 3,456 2.39 9,455 62.07 0.0296
2025-04-23 2025-03-31 13F WESTERN DIGITAL COM 958102105 144,307 6,947 5.06 5,834 -30.02 0.0202
2025-01-30 2024-12-31 13F WESTERN DIGITAL COM 958102105 137,360 5,159 3.90 8,338 -7.65 0.0286
2024-10-30 2024-09-30 13F WESTERN DIGITAL COM 958102105 132,201 6,762 5.39 9,028 -5.01 0.0321
2024-07-18 2024-06-30 13F WESTERN DIGITAL COM 958102105 125,439 -1,112 -0.88 9,505 10.06 0.0364
2024-05-02 2024-03-31 13F WESTERN DIGITAL COM 958102105 126,551 -6,930 -5.19 8,636 22.22 0.0333
2024-01-24 2023-12-31 13F WESTERN DIGITAL COM 958102105 133,481 -3,616 -2.64 7,065 12.95 0.0284
2023-10-19 2023-09-30 13F WESTERN DIGITAL COM 958102105 137,097 6,848 5.26 6,256 26.62 0.0279
2023-07-31 2023-06-30 13F WESTERN DIGITAL COM 958102105 130,249 -296 -0.23 4,940 0.47 0.0209
2023-04-25 2023-03-31 13F WESTERN DIGITAL COM 958102105 130,545 6,302 5.07 4,918 25.37 0.0223
2023-02-06 2022-12-31 13F WESTERN DIGITAL COM 958102105 124,243 -8,059 -6.09 3,922 -8.92 0.0191
2022-11-04 2022-09-30 13F WESTERN DIGITAL COM 958102105 132,302 241 0.18 4,306 -27.26 0.0219
2022-07-29 2022-06-30 13F WESTERN DIGITAL COM 958102105 132,061 -1,405 -1.05 5,920 -10.65 0.0278
2022-05-13 2022-03-31 13F WESTERN DIGITAL COM 958102105 133,466 -8,142 -5.75 6,626 -29.21 0.0259
2022-02-09 2021-12-31 13F WESTERN DIGITAL COM 958102105 141,608 1,900 1.36 9,360 18.71 0.0326
2021-11-02 2021-09-30 13F WESTERN DIGITAL COM 958102105 139,708 -4,048 -2.82 7,885 -22.93 0.0302
2021-08-03 2021-06-30 13F WESTERN DIGITAL COM 958102105 143,756 -5,739 -3.84 10,231 2.54 0.0381
2021-05-14 2021-03-31 13F WESTERN DIGITAL COM 958102105 149,495 -4,892 -3.17 9,978 33.27 0.0396
2021-02-12 2020-12-31 13F WESTERN DIGITAL COM 958102105 154,387 -377 -0.24 7,487 32.35 0.0308
2020-11-13 2020-09-30 13F WESTERN DIGITAL COM 958102105 154,764 -899 -0.58 5,657 -17.68 0.0260
2020-08-14 2020-06-30 13F WESTERN DIGITAL COM 958102105 155,663 373 0.24 6,872 6.33 0.0338
2020-05-14 2020-03-31 13F WESTERN DIGITAL COM 958102105 155,290 -886 -0.57 6,463 -34.80 0.0377
2020-02-14 2019-12-31 13F WESTERN DIGITAL COM 958102105 156,176 -1,467 -0.93 9,912 5.44 0.0447
2019-11-14 2019-09-30 13F WESTERN DIGITAL COM 958102105 157,643 2,618 1.69 9,401 27.52 0.0453
2019-08-14 2019-06-30 13F WESTERN DIGITAL COM 958102105 155,025 14,268 10.14 7,372 8.99 0.0362
2019-05-15 2019-03-31 13F WESTERN DIGITAL COM 958102105 140,757 -414,390 -74.65 6,764 -67.03 0.0366
2019-02-13 2018-12-31 13F WESTERN DIGITAL COM 958102105 555,147 32,460 6.21 20,515 -32.92 0.0489
2018-11-14 2018-09-30 13F WESTERN DIGITAL COM 958102105 522,687 42,376 8.82 30,581 -17.72 0.0628
2018-08-14 2018-06-30 13F WESTERN DIGITAL COM 958102105 480,311 10,290 2.19 37,169 -14.30 0.0812
2018-05-14 2018-03-31 13F WESTERN DIGITAL COM 958102105 470,021 -26,594 -5.36 43,369 9.63 0.0977
2018-02-14 2017-12-31 13F WESTERN DIGITAL COM 958102105 496,615 15,804 3.29 39,560 -4.81 0.0873
2017-11-14 2017-09-30 13F WESTERN DIGITAL COM 958102105 480,811 -4,253 -0.88 41,557 -3.52 0.0976
2017-08-14 2017-06-30 13F WESTERN DIGITAL COM 958102105 485,064 -32,294 -6.24 43,071 0.63 0.1099
2017-05-11 2017-03-31 13F WESTERN DIGITAL COM 958102105 517,358 -22,644 -4.19 42,801 16.51 0.1124
2017-05-02 2016-12-31 13F/A-1 WESTERN DIGITAL COM 958102105 540,002 483,522 856.09 36,737 1,016.29 0.0939
2017-02-13 2016-12-31 13F WESTERN DIGITAL COM 958102105 540,002 36,737
2016-11-07 2016-09-30 13F WESTERN DIGITAL Com 958102105 56,480 29,323 107.98 3,291 164.55 0.0489
2016-08-03 2016-06-30 13F WESTERN DIGITAL Com 958102105 27,157 1,542 6.02 1,244 4.71 0.0187
2016-05-05 2016-03-31 13F WESTERN DIGITAL Com 958102105 25,615 -405 -1.56 1,188 -25.05 0.0173
2016-01-28 2015-12-31 13F WESTERN DIGITAL Com 958102105 26,020 3,343 14.74 1,585 -1.18 0.0237
2015-11-12 2015-09-30 13F WESTERN DIGITAL Com 958102105 22,677 0 0.00 1,604 -13.16 0.0244
2015-08-06 2015-06-30 13F WESTERN DIGITAL Com 958102105 22,677 -3 -0.01 1,847 -12.01 0.0256
2015-05-11 2015-03-31 13F WESTERN DIGITAL Com 958102105 22,680 -73,323 -76.38 2,099 -80.34 0.0259
2015-02-09 2014-12-31 13F WESTERN DIGITAL Com 958102105 96,003 -2,182 -2.22 10,674 11.99 0.1385
2014-11-05 2014-09-30 13F WESTERN DIGITAL Com 958102105 98,185 -12,275 -11.11 9,531 -6.64 0.1316
2014-08-12 2014-06-30 13F WESTERN DIGITAL Com 958102105 110,460 0 0.00 10,209 1.25 0.1524
2014-05-05 2014-03-31 13F WESTERN DIGITAL Com 958102105 110,460 -189 -0.17 10,083 8.93 0.1589
2014-02-05 2013-12-31 13F/A-1 WESTERN DIGITAL COM 958102105 110,649 -45,141 -28.98 9,256 -6.26 0.1435
2014-01-29 2013-12-31 13F WESTERN DIGITAL COM 958102105 110,649 9,256
2014-02-05 2013-09-30 13F/A-1 WESTERN DIGITAL Com 958102105 155,790 -34,416 -18.09 9,874 -16.48 0.1486
2013-11-06 2013-09-30 13F WESTERN DIGITAL Com 958102105 155,790 9,874
2014-02-12 2013-06-30 13F/A-1 WESTERN DIGITAL COM 958102105 190,206 190,206 11,823 0.1920
2013-08-05 2013-06-30 13F WESTERN DIGITAL Com 958102105 190,206 11,823
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.