Costco Wholesale Corporation
US ˙ NasdaqGS ˙ US22160K1051

SecurityCOST / Costco Wholesale Corporation
InstitutionAssetmark, Inc
Latest Disclosed Ownership66,108 shares
Latest Disclosed Value $ 65,872,042
Assetmark, Inc reports 16.07% increase in ownership of COST / Costco Wholesale Corporation

On May 6, 2026 - Assetmark, Inc filed a 13F-HR form disclosing ownership of 66,108 shares of Costco Wholesale Corporation (US:COST) valued at $65,871,994 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 23, 2026 disclosing 56,955 shares of Costco Wholesale Corporation. This represents a change in shares of 16.07% during the quarter. The current value of the position is $63,584,658 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)
2026-05-06 2026-03-31 13F COSTCO WHOLESALE COM 22160K105 66,108 9,153 16.07 65,872 34.12 0.1343
2026-01-23 2025-12-31 13F COSTCO WHSL CORP COM 22160K105 56,955 2,897 5.36 49,114 -1.85 0.1002
2025-11-06 2025-09-30 13F COSTCO WHSL CORP COM 22160K105 54,058 -1,963 -3.50 50,038 -9.77 0.1073
2025-08-04 2025-06-30 13F COSTCO WHSL CORP COM 22160K105 56,021 8,873 18.82 55,457 24.37 0.1309
2025-05-06 2025-03-31 13F COSTCO WHSL CORP COM 22160K105 47,148 4,846 11.46 44,592 15.05 0.1225
2025-02-06 2024-12-31 13F COSTCO WHSL CORP COM 22160K105 42,302 2,671 6.74 38,760 10.32 0.1053
2024-11-01 2024-09-30 13F COSTCO WHSL CORP COM 22160K105 39,631 4,785 13.73 35,134 18.62 0.1006
2024-08-13 2024-06-30 13F COSTCO WHSL CORP COM 22160K105 34,846 4,420 14.53 29,619 32.88 0.0916
2024-05-07 2024-03-31 13F COSTCO WHSL CORP COM 22160K105 30,426 1,369 4.71 22,291 16.21 0.0725
2024-02-09 2023-12-31 13F COSTCO WHSL CORP COM 22160K105 29,057 -716 -2.40 19,180 14.03 0.0693
2023-10-27 2023-09-30 13F COSTCO WHSL CORP COM 22160K105 29,773 4,439 17.52 16,821 23.32 0.0673
2023-08-11 2023-06-30 13F COSTCO WHSL CORP NEW COM COM 22160K105 25,334 3,663 16.90 13,639 26.67 0.0535
2023-05-05 2023-03-31 13F COSTCO WHSL CORP NEW COM COM 22160K105 21,671 -1,914 -8.12 10,768 0.01 0.0445
2023-02-10 2022-12-31 13F COSTCO WHSL CORP COM 22160K105 23,585 5,081 27.46 10,767 23.19 0.0467
2022-11-01 2022-09-30 13F COSTCO WHSL CORP COM 22160K105 18,504 6,305 51.68 8,739 49.46 0.0409
2022-08-03 2022-06-30 13F COSTCO WHSL CORP NEW COM COM 22160K105 12,199 4,617 60.89 5,847 33.92 0.0262
2022-05-13 2022-03-31 13F COSTCO WHSL CORP NEW COM COM 22160K105 7,582 4,301 131.09 4,366 134.35 0.0183
2022-02-14 2021-12-31 13F COSTCO WHSL CORP NEW COM COM 22160K105 3,281 -5,296 -61.75 1,863 -51.66 0.0077
2021-11-12 2021-09-30 13F COSTCO WHSL CORP NEW COM COM 22160K105 8,577 8,103 1,709.49 3,854 1,950.00 0.0173
2021-08-16 2021-06-30 13F COSTCO WHSL CORP NEW COM COM 22160K105 474 9 1.94 188 14.63 0.0009
2021-05-14 2021-03-31 13F COSTCO WHSL CORP COM 22160K105 465 -302 -39.37 164 -43.25 0.0008
2021-02-10 2020-12-31 13F COSTCO WHSL CORP NEW COM COM 22160K105 767 1 0.13 289 6.25 0.0016
2020-11-13 2020-09-30 13F COSTCO WHSL CORP NEW COM COM 22160K105 766 -14,736 -95.06 272 -94.15 0.0018
2020-08-11 2020-06-30 13F COSTCO WHSL CORP NEW COM COM 22160K105 15,502 -3,475 -18.31 4,646 -14.14 0.0332
2020-05-12 2020-03-31 13F COSTCO WHSL CORP NEW COM COM 22160K105 18,977 18,523 4,079.96 5,411 3,968.42 0.0458
2020-02-11 2019-12-31 13F COSTCO WHSL CORP NEW COM COM 22160K105 454 11 2.48 133 3.91 0.0010
2019-11-13 2019-09-30 13F COSTCO WHSL CORP NEW COM COM 22160K105 443 19 4.48 128 14.29 0.0011
2019-08-14 2019-06-30 13F COSTCO WHSL CORP NEW COM COM 22160K105 424 117 38.11 112 51.35 0.0009
2019-05-14 2019-03-31 13F COSTCO WHSL CORP NEW COM COM 22160K105 307 -151 -32.97 74 -20.43 0.0007
2019-02-13 2018-12-31 13F COSTCO WHSL CORP NEW COM COM 22160K105 458 23 5.29 93 -8.82 0.0009
2018-11-13 2018-09-30 13F COSTCO WHSL CORP NEW COM COM 22160K105 435 77 21.51 102 36.00 0.0009
2018-08-01 2018-06-30 13F COSTCO WHSL CORP NEW COM COM 22160K105 358 -9 -2.45 75 8.70 0.0007
2018-05-16 2018-03-31 13F COSTCO WHSL CORP NEW COM COM 22160K105 367 -197 -34.93 69 -34.29 0.0007
2018-02-13 2017-12-31 13F COSTCO WHSL CORP NEW COM COM 22160K105 564 326 136.97 105 169.23 0.0011
2017-11-08 2017-09-30 13F COSTCO WHSL CORP NEW COM COM 22160K105 238 -437 -64.74 39 -63.89 0.0004
2017-08-14 2017-06-30 13F COSTCO WHSL CORP NEW COM COM 22160K105 675 503 292.44 108 272.41 0.0014
2017-09-15 2017-03-31 13F/A-1 COSTCO WHSL CORP NEW COM COM 22160K105 172 35 25.55 29 31.82 0.0004
2017-05-08 2017-03-31 13F COSTCO WHSL CORP NEW COM COM 22160K105 172 35 29
2017-09-15 2016-12-31 13F/A-1 COSTCO WHSL CORP NEW COM COM 22160K105 137 -109 -44.31 22 -42.11 0.0003
2017-02-14 2016-12-31 13F COSTCO WHSL CORP NEW COM COM 22160K105 137 -109 22
2017-09-14 2016-09-30 13F/A-1 COSTCO WHSL CORP NEW COM COM 22160K105 246 35 16.59 38 15.15 0.0006
2016-11-04 2016-09-30 13F COSTCO WHSL CORP NEW COM COM 22160K105 246 35 38
2017-09-14 2016-06-30 13F/A-1 COSTCO WHSL CORP NEW COM COM 22160K105 211 0 0.00 33 0.00 0.0006
2016-08-08 2016-06-30 13F COSTCO WHSL CORP NEW COM COM 22160K105 211 0 33
2017-09-14 2016-03-31 13F/A-1 COSTCO WHSL CORP NEW COM COM 22160K105 211 -42 -16.60 33 -19.51 0.0006
2016-05-13 2016-03-31 13F COSTCO WHSL CORP NEW COM COM 22160K105 211 -42 33
2017-09-14 2015-12-31 13F/A-1 COSTCO WHSL CORP NEW COM COM 22160K105 253 168 197.65 41 241.67 0.0008
2016-02-12 2015-12-31 13F COSTCO WHSL CORP NEW COM COM 22160K105 253 168 41
2016-01-05 2015-09-30 13F/A-1 COSTCO WHSL CORP NEW COM COM 22160K105 85 58 214.81 12 200.00 0.0003
2015-11-10 2015-09-30 13F COSTCO WHSL CORP NEW COM COM 22160K105 85 12
2015-08-13 2015-06-30 13F COSTCO WHSL CORP NEW COM COM 22160K105 27 27 4 0.0001
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.