Western Digital Corporation
CH ˙ BRSE ˙ US9581021055
DETTE SYMBOL ER IKKE LÆNGERE AKTIVT
SecurityCH:12355 / Western Digital Corporation
InstitutionAmeriprise Financial Inc
Latest Disclosed Ownership5,762,533 shares
Latest Disclosed Value $ 1,558,708,820
Ameriprise Financial Inc ownership in 12355 / Western Digital Corporation

On May 15, 2026 - Ameriprise Financial Inc filed a 13F-HR form disclosing ownership of 5,762,533 shares of Western Digital Corporation (CH:12355) valued at $1,558,708,820 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 8,520,425 shares of Western Digital Corporation. This represents a change in shares of -32.37% during the quarter.

Ameriprise Financial Inc has a history of taking positions in derivatives of the underlying security (12355) in the form of stock options.

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 5,762,533 -2,757,892 -32.37 1,558,709 6.19 0.0668
2026-02-17 2025-12-31 13F WESTERN DIGITAL COM 958102105 8,520,425 -162,894 -1.88 1,467,814 40.79 0.3317
2025-11-14 2025-09-30 13F WESTERN DIGITAL COM 958102105 8,683,319 -376,209 -4.15 1,042,520 79.83 0.2394
2025-08-14 2025-06-30 13F WESTERN DIGITAL COM 958102105 9,059,528 1,153,441 14.59 579,718 81.37 0.1429
2025-05-14 2025-03-31 13F WESTERN DIGITAL COM 958102105 7,906,087 1,353,799 20.66 319,639 -18.19 0.0863
2025-02-14 2024-12-31 13F WESTERN DIGITAL COM 958102105 6,552,288 7,081 0.11 390,713 -12.59 0.1002
2024-11-14 2024-09-30 13F WESTERN DIGITAL COM 958102105 6,545,207 1,016,562 18.39 446,972 6.70 0.1146
2024-08-14 2024-06-30 13F WESTERN DIGITAL COM 958102105 5,528,645 123,687 2.29 418,909 13.58 0.1134
2024-05-15 2024-03-31 13F WESTERN DIGITAL COM 958102105 5,404,958 1,256,100 30.28 368,836 69.74 0.1015
2024-02-14 2023-12-31 13F WESTERN DIGITAL COM 958102105 4,148,858 -478,053 -10.33 217,289 2.92 0.0651
2023-11-14 2023-09-30 13F WESTERN DIGITAL COM 958102105 4,626,911 -875,067 -15.90 211,126 1.17 0.0693
2023-08-14 2023-06-30 13F WESTERN DIGITAL COM 958102105 5,501,978 86,246 1.59 208,690 2.29 0.0654
2023-05-22 2023-03-31 13F/A-1 WESTERN DIGITAL COM 958102105 5,415,732 -153,641 -2.76 204,011 16.10 0.0669
2023-05-15 2023-03-31 13F WESTERN ASSET DIVERS COM 958102105 5,415,732 -153,641 204,011 0.0123
2023-02-14 2022-12-31 13F WESTERN DIGITAL COM 958102105 5,569,373 -156,057 -2.73 175,721 -5.71 0.0602
2022-11-14 2022-09-30 13F WESTERN DIGITAL COM 958102105 5,725,430 -2,330,106 -28.93 186,364 -48.39 0.0689
2022-08-15 2022-06-30 13F WESTERN DIGITAL COM 958102105 8,055,536 -32,076 -0.40 361,132 -10.06 0.1260
2022-05-16 2022-03-31 13F WESTERN DIGITAL COM 958102105 8,087,612 182,260 2.31 401,520 -22.10 0.1185
2022-02-14 2021-12-31 13F WESTERN DIGITAL COM 958102105 7,905,352 -404,596 -4.87 515,447 9.90 0.1426
2021-11-15 2021-09-30 13F WESTERN DIGITAL COM 958102105 8,309,948 -366,922 -4.23 469,011 -24.05 0.1498
2021-08-16 2021-06-30 13F WESTERN DIGITAL COM 958102105 8,676,870 -1,290,060 -12.94 617,534 -7.18 0.1909
2021-05-17 2021-03-31 13F WESTERN DIGITAL COM 958102105 9,966,930 -287,256 -2.80 665,286 17.13 0.2211
2021-02-12 2020-12-31 13F WESTERN DIGITAL COM 958102105 10,254,186 -87,691 -0.85 567,969 50.25 0.2014
2020-11-16 2020-09-30 13F WESTERN DIGITAL COM 958102105 10,341,877 1,173,865 12.80 378,011 -6.61 0.1538
2020-08-14 2020-06-30 13F WESTERN DIGITAL COM 958102105 9,168,012 1,071,734 13.24 404,771 20.17 0.1734
2020-05-15 2020-03-31 13F WESTERN DIGITAL COM 958102105 8,096,278 1,855,626 29.73 336,822 -14.96 0.1768
2020-02-14 2019-12-31 13F WESTERN DIGITAL COM 958102105 6,240,652 814,114 15.00 396,094 22.39 0.1647
2019-11-14 2019-09-30 13F WESTERN DIGITAL COM 958102105 5,426,538 -344,396 -5.97 323,643 17.94 0.1450
2019-08-14 2019-06-30 13F WESTERN DIGITAL COM 958102105 5,770,934 294,334 5.37 274,409 4.24 0.1229
2019-05-15 2019-03-31 13F WESTERN DIGITAL COM 958102105 5,476,600 852,538 18.44 263,239 53.95 0.1211
2019-02-14 2018-12-31 13F WESTERN DIGITAL COM 958102105 4,624,062 48,541 1.06 170,992 -36.17 0.0855
2018-11-14 2018-09-30 13F WESTERN DIGITAL COM 958102105 4,575,521 75,093 1.67 267,878 -23.10 0.0936
2018-08-14 2018-06-30 13F WESTERN DIGITAL COM 958102105 4,500,428 219,257 5.12 348,330 -11.83 0.1541
2018-05-14 2018-03-31 13F WESTERN DIGITAL COM 958102105 4,281,171 400,435 10.32 395,047 27.98 0.1787
2018-02-12 2017-12-31 13F WESTERN DIGITAL COM 958102105 3,880,736 -183,014 -4.50 308,673 -12.09 0.1408
2017-11-07 2017-09-30 13F WESTERN DIGITAL COM 958102105 4,063,750 -380,116 -8.55 351,139 -10.83 0.1671
2017-08-10 2017-06-30 13F WESTERN DIGITAL COM 958102105 4,443,866 405,293 10.04 393,778 18.22 0.1971
2017-05-05 2017-03-31 13F WESTERN DIGITAL COM 958102105 4,038,573 380,404 10.40 333,102 33.99 0.1724
2017-02-03 2016-12-31 13F WESTERN DIGITAL COM 958102105 3,658,169 1,314,650 56.10 248,611 81.39 0.1357
2016-11-08 2016-09-30 13F WESTERN DIGITAL COM 958102105 2,343,519 525,312 28.89 137,057 59.44 0.0768
2016-08-08 2016-06-30 13F WESTERN DIGITAL COM 958102105 1,818,207 355,374 24.29 85,964 24.37 0.0504
2016-05-12 2016-03-31 13F WESTERN DIGITAL COM 958102105 1,462,833 730,884 99.85 69,118 57.16 0.0412
2016-02-11 2015-12-31 13F WESTERN DIGITAL COM 958102105 731,949 220,566 43.13 43,980 8.17 0.0258
2015-11-12 2015-09-30 13F WESTERN DIGITAL COM 958102105 511,383 -14,611 -2.78 40,657 -1.43 0.0252
2015-08-13 2015-06-30 13F WESTERN DIGITAL COM 958102105 525,994 -272,079 -34.09 41,247 -43.21 0.0235
2015-05-14 2015-03-31 13F WESTERN DIGITAL COM 958102105 798,073 356,288 80.65 72,634 48.48 0.0417
2015-02-13 2014-12-31 13F WESTERN DIGITAL COM 958102105 441,785 5,337 1.22 48,920 15.17 0.0285
2014-11-14 2014-09-30 13F WESTERN DIGITAL COM 958102105 436,448 -62,848 -12.59 42,476 -7.86 0.0256
2014-08-13 2014-06-30 13F WESTERN DIGITAL COM 958102105 499,296 64,057 14.72 46,099 15.33 0.0272
2014-05-14 2014-03-31 13F WESTERN DIGITAL COM 958102105 435,239 228,951 110.99 39,973 130.83 0.0240
2014-02-14 2013-12-31 13F WESTERN DIGITAL COM 958102105 206,288 67,158 48.27 17,317 96.16 0.0105
2013-11-14 2013-09-30 13F WESTERN DIGITAL COM 958102105 139,130 -32,600 -18.98 8,828 -17.28 0.0058
2013-08-14 2013-06-30 13F WESTERN DIGITAL COM 958102105 171,730 171,730 10,672 0.0074
Disclosed Put 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 OPT Put 10,600 2,867 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.