Costco Wholesale Corporation
US ˙ NasdaqGS ˙ US22160K1051

SecurityCOST / Costco Wholesale Corporation
InstitutionWhittier Trust Co
Latest Disclosed Ownership67,317 shares
Latest Disclosed Value $ 68,565,420
Whittier Trust Co reports 4.18% increase in ownership of COST / Costco Wholesale Corporation

On April 28, 2026 - Whittier Trust Co filed a 13F-HR form disclosing ownership of 67,317 shares of Costco Wholesale Corporation (US:COST) valued at $67,076,678 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 26, 2026 disclosing 64,616 shares of Costco Wholesale Corporation. This represents a change in shares of 4.18% during the quarter. The current value of the position is $64,747,510 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)
2026-04-28 2026-03-31 13F COSTCO WHOLESALE common 22160K105 67,317 2,701 4.18 68,565 19.35 0.7737
2026-01-26 2025-12-31 13F COSTCO WHOLESALE common 22160K105 64,616 782 1.23 57,450 -1.68 0.6221
2025-10-31 2025-09-30 13F COSTCO WHSL CORP common 22160K105 63,834 717 1.14 58,433 -6.48 0.6651
2025-07-30 2025-06-30 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 63,117 3,038 5.06 62,481 9.96 0.7534
2025-05-02 2025-03-31 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 60,079 -331 -0.55 56,821 2.65 0.7915
2025-02-11 2024-12-31 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 60,410 1,079 1.82 55,351 5.24 0.7292
2024-10-21 2024-09-30 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 59,331 799 1.37 52,598 5.72 0.7039
2024-07-29 2024-06-30 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 58,532 446 0.77 49,750 16.91 0.7058
2024-05-02 2024-03-31 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 58,086 706 1.23 42,555 12.36 0.6205
2024-01-11 2023-12-31 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 57,380 -71 -0.12 37,875 16.69 0.6140
2023-10-27 2023-09-30 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 57,451 803 1.42 32,456 6.42 0.5768
2023-07-24 2023-06-30 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 56,648 -1,642 -2.82 30,498 5.30 0.5301
2023-04-21 2023-03-31 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 58,290 387 0.67 28,962 9.57 0.5273
2023-01-25 2022-12-31 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 57,903 300 0.52 26,433 -2.83 0.5142
2022-10-21 2022-09-30 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 57,603 -3,587 -5.86 27,203 -7.24 0.5701
2022-07-28 2022-06-30 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 61,190 -338 -0.55 29,326 -17.23 0.5923
2022-04-29 2022-03-31 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 61,528 6,770 12.36 35,430 13.97 0.5975
2022-01-19 2021-12-31 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 54,758 2,677 5.14 31,086 32.83 0.5051
2021-11-01 2021-09-30 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 52,081 -272 -0.52 23,402 12.98 0.4261
2021-07-29 2021-06-30 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 52,353 959 1.87 20,714 14.35 0.3690
2021-04-26 2021-03-31 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 51,394 2,838 5.84 18,114 -0.98 0.3518
2021-01-29 2020-12-31 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 48,556 1,391 2.95 18,294 9.26 0.3908
2020-10-30 2020-09-30 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 47,165 451 0.97 16,744 18.22 0.3987
2020-07-10 2020-06-30 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 46,714 -1,226 -2.56 14,163 3.61 0.3933
2020-04-27 2020-03-31 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 47,940 -1,913 -3.84 13,669 -6.71 0.4463
2020-01-31 2019-12-31 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 49,853 144 0.29 14,652 2.31 0.3844
2019-10-18 2019-09-30 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 49,709 119 0.24 14,321 9.28 0.4099
2019-07-23 2019-06-30 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 49,590 234 0.47 13,105 9.66 0.3848
2019-04-29 2019-03-31 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 49,356 -162 -0.33 11,951 18.48 0.3654
2019-02-07 2018-12-31 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 49,518 642 1.31 10,087 -12.13 0.3470
2018-10-23 2018-09-30 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 48,876 285 0.59 11,480 13.06 0.3582
2018-07-27 2018-06-30 13F/A-1 COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 48,591 587 1.22 10,154 12.26 0.3354
2018-07-20 2018-06-30 13F COSTCO WHSL CORP NEW COM US LARGE CAP EQUITIES 22160K105 17,979 -30,025 2,070
2018-05-01 2018-03-31 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 48,004 1,827 3.96 9,045 5.24 0.3039
2018-02-07 2017-12-31 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 46,177 -362 -0.78 8,595 12.41 0.2998
2017-10-23 2017-09-30 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 46,539 6,762 17.00 7,646 20.20 0.2787
2017-07-20 2017-06-30 13F COSTCO WHSL CORP NEW COM US LARGE-CAP EQUITIES 22160K105 39,777 17,865 81.53 6,361 73.14 0.2459
2017-04-26 2017-03-31 13F COSTCO WHSL CORP US LARGE CAP EQUITIES 22160K105 21,912 1,310 6.36 3,674 11.37 0.1482
2017-01-18 2016-12-31 13F COSTCO WHSL CORP NEW COM US LARGE CAP EQUITIES 22160K105 20,602 -1,026 -4.74 3,299 0.00 0.1403
2016-11-10 2016-09-30 13F COSTCO WHSL CORP NEW COM US LARGE CAP EQUITIES 22160K105 21,628 -456 -2.06 3,299 -4.87 0.1437
2016-07-28 2016-06-30 13F COSTCO WHSL CORP NEW COM US LARGE CAP EQUITIES 22160K105 22,084 -80 -0.36 3,468 -0.72 0.1528
2016-04-28 2016-03-31 13F COSTCO WHSL CORP NEW COM US LARGE CAP EQUITIES 22160K105 22,164 -35 -0.16 3,493 -2.59 0.1545
2016-02-10 2015-12-31 13F COSTCO WHSL CORP NEW COM US LARGE CAP EQUITIES 22160K105 22,199 3,666 19.78 3,586 33.81 0.1627
2015-11-12 2015-09-30 13F COSTCO WHSL CORP NEW COM US LARGE CAP EQUITIES 22160K105 18,533 -6,824 -26.91 2,680 -21.75 0.1304
2015-08-13 2015-06-30 13F COSTCO WHSL CORP NEW COM US LARGE CAP EQUITIES 22160K105 25,357 7,324 40.61 3,425 25.41 0.1520
2015-05-05 2015-03-31 13F COSTCO WHSL CORP NEW COM US LARGE CAP EQUITIES 22160K105 18,033 18,033 0.00 2,731 0.1252
2015-02-04 2014-12-31 13F COSTCO WHSL CORP NEW COM US LARGE CAP EQUITIES 22160K105 0 -18,112 -100.00 0 -100.00
2014-11-07 2014-09-30 13F COSTCO WHSL CORP NEW COM US LARGE CAP EQUITIES 22160K105 18,112 133 0.74 2,269 9.61 0.1106
2014-08-04 2014-06-30 13F COSTCO WHSL CORP NEW COM US LARGE CAP EQUITIES 22160K105 17,979 -900 -4.77 2,070 -1.80 0.1021
2014-05-01 2014-03-31 13F COSTCO WHSL CORP NEW COM US LARGE CAP EQUITIES 22160K105 18,879 -158 -0.83 2,108 -6.97 0.1080
2014-02-05 2013-12-31 13F COSTCO WHSL CORP NEW COM US LARGE CAP EQUITIES 22160K105 19,037 0 0.00 2,266 3.33 0.1162
2013-11-18 2013-09-30 13F COSTCO WHSL CORP COM 22160K105 19,037 0 0.00 2,193 4.18 0.1187
2013-08-14 2013-06-30 13F COSTCO WHSL CORP COM 22160K105 19,037 19,037 2,105 0.1179
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.